Blender Rigid Body Simulations

1. Trailer: Have you ever wanted to create mind blowing physics simulations Blender, whether it's realistic object collisions, destructions, or intricate chain reactions. This course will teach you everything you need to know about rigid body simulations. Anya seen a three D artist and instructor with over 7,000 students. And in this course, we're diving deep into Blenders physics engine. No flock just hands on learning with real problems. You start with the fundamentals what rigid bodies are and how they work. Then we will break down settings like mass, collision shapes, and surface response. So you can optimize your simulations for realism and efficiency. We'll also explore the rigid body world settings, giving you full control over gravity, speed, and interactions. But the real magic happens when we apply these concepts into practical projects. We'll make a line of domino pieces fall in perfect sequince. We'll create this mesmerizing gltenbard simulation that forms a perfect bell curve. And finally, we will construct a building only to demolish it in a spectacular simulation. This course is designed to take you from a beginner to a confident physics artist with easy to follow lessons and hands on experience. So if you're ready to bring your three D scenes to life with physics enroll now, and let's get started. 2. What are Rigid Body Simulations: What are rigid body simulations? There are many types of three D simulations fluid dynamic, volume simulations, soft body dynamics, and so on. Among these, rigid body simulations are a key category. Unlike simulations that model deformation or fluid flow, rigid body simulations focus on calculating the movement of solid, non flexible objects. Specifically, they track the changes in an object's position or rotation without altering its form. So if you're simulating interactions between solid objects like colliding blocks or folding debris and want to preserve their structure, rigid body simulations are the way to go. Let's jump into blender and learn the basics of how this works. Okay, so welcome in Blender, and this is a really basic scene. I have this plane with this grid texture slapped on it, and also I have this red sphere. Let's say, hypothetically, I want to simulate how will this red sphere fall? And this is an instance where we can use the power of the rigid body system in blender to do these sort of simulations. And all you need to do is to make sure you're selecting your sphere. Next, jump to the physics stab, and from here, you can add a rigid body system to your object. And now if I hit play, this sphere will start falling indefinitely. Adding a rigid body system or a rigid body simulation to an object is just as easy as just clicking this rigid body button, and by doing that, you will have a basic rigid body simulation going on. But let's say I want this ball to bounce on this floor. So we need to figure out a way to tell Blender that, Hey, Blender, consider this the ground. The problem is if I add a rigid body to it and then hit play, you will notice that they both will fall, and this is where this type will play a role. From here, you can change the type from either active or passive. If I select this plane and change its type to passive, now if I hit play, you will notice that the ball will basically fall on this floor. In the next couple of videos, we are going to go over all the different settings, so don't worry about that. This is just an example to showcase the logic and the philosophy behind how the rigid body system works in blender. So this sphere is set to active, which means it can move and all of that. Meanwhile, the objects that I don't want them to move or I just want them, let's say, to be obstacles, I'm going to set them to passive. I'm going to show the blue ball also, and I also have this collection called obstacles, which if I enable it, you will have these wood pieces that will act as obstacles. If I hit play now, only the red ball will move let's say I also want to move this blue ball. I'm going to add a rigid body to it, and also I will set it to active because I wanted to move. I wanted to be part of the simulation. If I had play, both of those two balls will fall. But I want also these wood pieces to be part of the simulation. That's why I'm going to select, for example, the first one, add a rigid body to it, and I don't want it to move. I want them to be static. That's why I'm going to change the type from active to passive, same thing for the second one, add a rigid body to it and change it to passive, and same thing for the third one, add a rigid body and change it to passive. And now if I hit play, notice what will happen. As you can see, both the two balls will start colliding with these wood pieces, but also at the same time, they will collide with each other and they will push each other as you can see. And this is the most vanilla version of how you can create rigid body simulations in blender. 3. Rigid Body Settings: Rigid body settings. Hey, everyone. Welcome back. In this video we'll explore the setting step of rigid bodies. We'll cover the basics like mass, and we'll also explore what these two settings do dynamic and animated. So yeah, let's dive in. Welcome to another basic scene inside of blender. Let's say I want to make this red ball fall. As we talked about that before, first of all, jump to the physics stab, add rigid body system to it. And let's start, first of all, talking about the type which is either active or passive. When we talk about an active object, that basically means that the object will be directly controlled by the simulation results. In the object will be part of the simulation and it will be dynamic and it will be moving around. We want this red sphere to fall and move and all of that. That's why I'm going to set its type to active. Now if I hit play, you will notice that the ball will fall. The only problem is that the ball will go through the floor because blender right now doesn't consider this floor part of the simulation. Select this plane, add to it another rigid body system, and in this situation, if I keep it the plane will also fall with the ball, but we need it to stay aesthetic object. And that's what you can exactly do by selecting the plane and changing the type from active to passive. You can think of a passive object as just aesthetic object that the other objects will react with. It won't move or any of that. It is just there to control the simulation or to act as a passive object, basically. So now if I hit play, you will notice that this ball will fall on the floor. And this is the difference between an active object and a passive object. One of them will move and react with all the different objects, and one of them is you can think of it as an obstacle. And that obstacle is used for the other objects to react to. And right now, we created a really basic scene or really basic simulation where this red ball is falling. Jump to the other settings right now. I'm going to select the ball and let's talk about the other settings that are right here. First of all, you have the mass. I think that should be self explanatory, which is the mass of the object. And one of the nice things about blender is that while you're selecting a certain object, if you jump to the window object, then jump to rigid body, you will have here an option for calculate mass. If I click on it, Blender will give you different presets or different materials that a blender will use to calculate or to estimate the mass of such an object. Let's say, for example, if this bowl was made of iron, as you can see, Blender will tell you that probably the mess of this ball will be 876 kilos. So that's a handy option that can help you if you want to create more accurate simulations. I'm going to put this back to one. And now let's move on to this dynamic option and the animated option. When it comes to moving objects in blender, there are two main systems for that. One of them is called the dynamic system, which means that the object will move and all of that based on the simulations, based on the dynamic, based on the physics system, and the other option is animated, which is another way to move the object or transform it by using keyframes using the timeline. The animated option is more powerful than the dynamic option. And what I mean by powerful is that if I check the option for animated, that will cancel the dynamic system. Now, because I checked animated, if I go to frame number one and hit play Nothing will happen because when you check the animated boxes, that's a way to tell Blender that, Hey, Blender, I'm going to move this object based on the animation system, which means I'm going to create keyframes and all of that. Meanwhile, if I disable the animated option, now this object will be controlled by the physics system. Now you might wonder, how is this supposed to be help? Actually, a lot of time you will find yourself wanting to do some sort of keyframe animations, and later on, the keyframe animations will turn into a physical simulation. Here's an example. I'm going to go back to frame number one. I'm going to select this ball, hit Alt g to clear the position, which will move this point to the center of the scene. I'm going to hit three also from the number pad to jump to the side view, and let's move it somewhere right here, let's say. So now I have the following scene, and actually I want this ball to be around here. So I'm going to hit seven and let's move it here. Let's say, hypothetically, I want to push this ball so it pushes this wood board. In such a scenario, you will find yourself wanting to use the animated option because you want to control the position of this red ball using key frames and later on switch it to a dynamic option so it can be part of the simulation. First of all, I'm going to select this wood board, and I'm going to add a rigid body system to it. I want to keep it as active because I want it to fall and move and all of that, so it should active and I'm going to leave the mass the way it is 1 kilogram. I'm going to jump back to this ball, and I want to move this red ball so it pushes this wood board. So while you're selecting this sphere, make sure to check the animated option. Let's jump to frame number one. Hit K to add a keyframe, and let's add a keyframe for the location. I'm going to move forward 30 frames to the frame number 30, JX to move it on the X axis, and let's push it here. Hit K again, and let's insert another keyframe for the location. And now if I jump to frame number one and hit play, notice what will happen. Basically, we were able to animate this ball and the other objects will react to that in a physical way. Something else you can do because this ball right now is only controlled by the animated system. For example, you can jump to the frame number 29 and create a keyframe for the animated option. So up until the frame 29, this ball is controlled by the animation system. At frame number 30, I'm going to turn this off and create another key frame. So at frame number 30, this sphere is not controlled by the animation system anymore. Now it will start to react in a physical way using the dynamic system or the physics system inside of blender. If I jump back to the frame number one, hit play, notice what will happen. So as you can see, the ball right now will continue moving because after frame 29, it is controlled by the physics system. So in summary, if you check the animated option, the object will only move based on the animation system. Blender will not consider the dynamic system in that situation because it is like you told Blender that, Hey, blender, I'm going to handle this object by myself using the animation system, and that object will only move based on the key frames you will set. And if you disable the animated option and keep the option, that means that you told Blender that, Hey, blender, handle everything yourself using the dynamic and the physics rules you have. And if you enable the dynamic option, basically nothing will happen and that object will stay static. In this situation, I'm going to keep it on. And yeah, that's basically it for the option for dynamic and animated. And by the way, if I select this plane, you will notice that when you have an object that is set to pass will only have one option which is animated, which means that only in case you want to move this floor, you can check this animated option, but it can't be a dynamic option because it is set to passive. And as I said before, when you set an object to passive, that means that that object will not move. It is a static object. That's why Blender doesn't give you the option for the dynamic checkbox. I hope the difference right now should be clear between dynamic and animated, and I will see you in the next video. 4. Rigid Body Collision Shape and Source: Rigid body collision shape and source. Hey, everyone. Welcome back. The collisions and Dynamics tab is arguably one of the most important parts of creating any rigid body simulation. It plays a huge role in shaping the final look of your simulation and determines how Blender handled the physics in your scene. In this video, we'll dive deep into all the settings. Break down what they do and highlight some key points to keep in mind. Let's get into it. Okay, so hello and welcome back inside of blender. This time we have a slightly more complex scene. We have this scar. We have this woodbard and we have this floor. Let's say, hypothetically, I want to make this scar to fall on this woodbard. Of course, later it will slide and fall on this plane. So first thing, we need to add a rigid body to this one. So make sure to select your car, jump to the physics step, and then jump to rigid body. I think the mass of the car should be around 1,500 kilograms or 1.5 tons, and I'm going to leave the collision shapes the way they are. In the previous video, we talked about the mass. We talked about the dynamic and animated option. And in this video, we will talk about the collision settings and all the other ones here. So I'm going to leave these settings the way they are, and I will explain them in a bit. Next, I'm going to jump to this wood board, and it should be a passive rigid body. So go rigid body and then change it from active to passive. And same thing for this plane, rigid body, change it from active to passive, and that's basically it. Now, if I jump to frame number one and hit play, notice what will happen. Car is sliding, but it will stop there, which is not realistic. So right now, let's start talking about the collision shapes. I'm going to select this scar, and you will see this option called shape. If I open shape, you will have different settings, and by default, Blender will have this set to convex hull. The shape option is a way to tell blender to calculate the simulation based on another shape. Here's what I mean. First of all, you will notice that all of these are divided into different categories. The first one called primitive base shapes, which is box, sphere, capsule, and cylinder and cone, and the other ones are mesh based shapes, convex hole, mesh, and compound parent. First ones or the primitive based shapes, they always stay the same. Meanwhile, the last three options depends on the shape. For example, let's say I check sphere in this time. You will notice that I will have the sphere surrounding the scar. That means that blender right now will treat the scar as a sphere when running the simulation. So if I go back to frame number one and I hit play, notice how the scar will act. It will fall, and then it will slide just like a sphere. Now if I set this from sphere, for example, to box, notice what will happen. Now it basically fall like a box. Let's change, for example, to capsule and hit play, and you will notice how this car is right now sliding. This is actually kind of realistic. Let's change to cone or first of all, cylinder, and you will notice that this car right now when it will fall, it will basically look like a cylinder, not like this complex object that is the car. Hit play. It didn't do what I had in mind. I thought maybe it will slide or any of that, but it didn't do any of that. And the last option is cone. If I go to frame number one and hit play, this is what you will get. And because of the shape of the cone, you will notice that the car is clipping the wood board right here. So this is it for the primitive base shapes. These shapes will stay the same regardless of the object. The last three option, convex hole, mesh, and compound parent will vary and change depending on the nature and the mesh of the object. Let's first of all, start with the convex hole. Sadly blender will not show you the shape here in the view port of the different categories that are mesh based. But if you hover, for example, over convex hole, you will have this short definition, which is that a convex hole is a mesh like surface encompassing all vertices. One way to visualize how this will look like if I select the scar, hit tab to jump to the edit mode, and hit A to select the entire mesh, and then if I go to mesh, you will have here an option called convex hole. If I click on it, look how this car is now transformed. A convex hole is basically a way to wrap an object in a bigger object. This will also make the process of calculating the simulation easier for blender because it doesn't need to count for all the different vertices that are forming your complex object. So for our car, this is how this convex hole will look like. So I'm going to hit Control Z to go back to my previous state hit tab again, let me jump back to frame number one. And if I hit play right now, Notice what will happen. This is how the car will fall, which is not that realistic. It is definitely better than some options we saw in the primitive base shapes, but still it doesn't look that good. Convex hole is a double edged sword. For certain objects, it works really well, and for other objects, it is terrible. So experiment with it. And generally, the best option you can always pick, which is also the most taxing on your system, is mesh because blender will calculate everything based on the mesh of your object. I'm going to select mesh, and if I jump to frame number one and hit play, notice right now how the scar will fall. Fall like that, and this is really realistic. By far, this is the best result we've got. You can see how the car will fall in a really realistic way. The only problem, as I said, this is really taxing, and it is really prone to error. Blender is not that good when it comes to calculating simulations for complex objects. If I go back, for example, around here, notice how the car is wiggling. I don't know if that will happen in real life, but it definitely looks slightly weird, and I think that part of it is how Blender is not doing a good job calculating or estimating how the simulation will look maybe also it is because of the nature of my object because it is not that smooth. But regardless, when it comes to mesh, always think about it as blender calculating the final result based on the actual mesh of the object. It will give you the most realistic result most of the time, but keep in mind that it can be a little glitchy. The last option is compound parent, which blender will tell you that it combines all of its direct rigid body children into one rigid body object. This is just a fancy way to say that if you have some children to this object, blender will add them to the shape of the object. Just as an example, let's say I go Shift A and let's add a UVsphere, I'm going to hit J and move it above the car. Let's say something like so. Let's say we put it right here and I'm going to make it a children of this car. First of all, I'm going to move this sphere into the collection of the car. I'm going to select the sphere, shift and select the car, control P, and set parent to object. Right now, whenever I move this car, this sphere will be tied to it. We say that this sphere right now is a child of this car object, which is just a fancy way to say that they are two separate objects, but they are connected. But the most important thing, this sphere is still its own object. If I open the car object, you will notice that you have this sphere right here, and later on, you can unpair in them and have them as separate objects again. Is a really useful feature that you can always find yourself using. I'm going back to my car, and in the settings, if I leave this to mesh, look how the simulation will play. The simulation will play like if this sphere is not doing anything. Look how it even collides and clip with the floor. But let's say I want it to be part of the simulation. That's why you can change the shape from mesh to compound parent. And the first thing that you will notice that a blender will tell you there are no child rigid bodies, which means that I also need to add a rigid body system to the children object. Situation, I'm going to select the sphere, add a rigid body to it, and I'm going to keep it the way it is. And if I jump back to the car, that notification right here will disappear. And now if I hit play, notice what will happen. Okay, Blender is not doing a good job at calculating what should happen, but I think you get the point. When you set this option to compound parent, Blender will also consider the children object in the simulation, and this can be a really useful option when you have two objects that you want to combine with each other, but you want to have them as separate objects. The car and the sphere. You don't want to merge them into one single mesh. You want to keep them as separate objects. So this option for the compound parent can be really useful. But as I said, blender is not that good when it comes to calculating the collision shapes for all of these complex objects. So for our example, I'm going to select the sphere, and I'm going to delete because I don't need it. So this is it for the collision shapes, I'm going to set this bad boy back to mesh, and you might wonder Okay, how is this supposed to be useful? The shape option is just a way to make the process of calculating the simulation slightly easier for blender by using some basic shapes or in general, a simplified version of the mesh of the object. Let's right now move on to the next option, which is source, which is either base, deform Final. Let's start with base, and to fully understand what's happening, I'm going, for example, to add a modifier, and let's say subdivision surface modifier. The car will look all weird right now, but it is not a problem. And I'm going to add another modifier, let's say, for example, the bend modifier. It it is called deform simple deform up, this one, and I'm going to change the type to bend. And let's, for example, increase the angle to something like 180. So we will have this really weird shaped car. I'm going to jump to the physics stab, and when we set this to mesh, does Blender consider the modifiers when calculating the mesh or not? This is where the source comes into place. So when I set this to base, Blender will calculate the mesh based on the original geometry and will not consider the modifiers. If I hit play, notice how this object will fall. I will fall like usual, which is not looking good. For the second option, which is called deform, blender will only consider the modifiers that are doing some deforming to the object. If I jump back to the modifier tab, we have a subdivision surface, and we have a simple deform. The subdivision surface is not a deforming modifier. It is a modifier used to add more geometry to the object. So blender, when I set this option to deform, will not consider the subdivision surface when running the simulation. But since the simple deform is deforming the object, Blender will look at this and we put it, and we'll calculate it and make it a part of the simulation. So now if I jump back to the physics step and it is set to deform, and if I hit play, notice how the sphere or the scar will fall. As you can see, blender right now is considering the deform modifier into the simulation. Now, it might look similar to what we had when we said this to base, but I promise you, this is what this deform option is doing. And lastly, the final option, which is called a final Blender will consider all the modifiers when calculating the simulation, and if I hit play, let's hope blender will not crash, you will have something looking like this, which is way more realistic. If I just disable this modifier subdivision for a second, this is the previous mesh. When I said this to deform, this is the shape that blender is calculating or the shape blender is seeing. But when I said this to final and let me activate the subdivision modifier, this is the shape blender will calculate when running the simulation. Are all just some simple ways of how you can simplify your geometry so the blender will have an easier time when calculating the simulation. So this is it for the collision shapes, and I will see you in the next video. 5. Rigid Body Surface Response and Sensitivity: Rigid body surface response and sensitivity. Hey, everyone. Welcome back. Aside from an object's mass, another key property is the surface response. This refers to how an object will behave in a simulation. Does it bounce like rubber, or is it rigid like metal or stone? In this video, we'll explore the settings that define both the surface response and sensitivity. Hello, and welcome back to another basic scene inside of blender. I have multiple objects in the scene right now. We will be using some other objects later. But right now, let's focus on this red ball and in this huge sponge. So let's say, hypothetically, I want to make this ball fall on this sponge. So first of all, select the ball, add a rigid body to it. I'm going to leave the type to active because I want it to move as usual. For the mass, let's leave it at 1 kilogram, and I'm going to change the shape from convex hole to sphere to make the process of calculations a little bit easier for blender. Same thing, I'm going to select this sponge, add a rigid body to it and it should be a passive object, and for the shape, I'm going to make it the simplest shape, which is a box. Now, if I hit play, the ball will fall on the sponge. Now, let's think realistically what should happen. When this ball will fall, it should bounce off this sponge. So how can we tell blender to also do that, basically? This is where the settings related to the surface response and sensitivity comes in. I'm going to select, first of all, the sponge because it is the main object that is causing the bounciness. So I will select it, and you will have here a tab called surface response. Or you will have two options. One of them is friction and the other one is bounciness. If I hover over friction, you will have the following definition. It is the resistance of an object to movement, and the other one is bounciness, which the tendency of an object to bounce after colliding with one another. Zero means it will stay still, and one means that it will perfectly be elastic. The best way I can explain it, you can think of friction when an object is moving on another object. That's where friction will play a role. And when it comes to bounciness is basically when two objects will collide. Our situation, let's say we want this ball to bounce on this sponge. So if I select the sponge and bring the value of bounciness up to one and hit play, notice what will happen. It won't bounce that much. The reason is because also this ball, let's say it is a plastic ball and the bounciness is set to zero. So let's say hypothetically I set it also to one, which means perfectly elastic. Now look at what will happen. I will hit play, and as you can see, the ball will keep bouncing forever. If, for example, I lower this value to something like 0.5 and hit play again, it will bounce less until it settle on the floor. Also if I lower the value for the bounciness here, let's say, for example, 0.5, it will bounce even less. So this is for bounciness. Basically, how will two objects bounce of each other if they collide? The bounciness plays a role when two objects are colliding. Now let's talk a little bit about friction. I'm going to disable, for example, the red ball. I'm going to hide it from the view and the render, so Blender will not calculate it. I'm going to show the obstacle, which is this wood piece right here and also this metal box right here. And let's say hypothetically, I want to simulate how will this iron or metal cube will slide on this woodbard and later will fall on the sponge. I'm going to select first of all, the cube. This should be an active object. I'm going to add a rigid body to it, set it to active. And for the mass, I can jump to object and then rigid body, and then you will have here an option for calculate mass. And right here, you should have an option for iron. So I'm going to select iron and Blender will estimate that the mass of such an object will be 105 kilograms. Can be useful, as you can see sometimes. For the shape, I'm going to change it from convex hole to a box because it is literally a box. And same thing for this wood piece, I'm going to do a rigid body, and this time it should be a passive object, and I'm going to change also the shape from convex hole to a box. This is the most basic setup you can use to create the simulation. I'm going to jump to frame number one. And let's hit play, and as you can see, this is how this cube will fall. But this doesn't look that realistic. The main reason is this metal cube is really heavy and it should do a lot of friction with this wood piece. That's where the friction value will play a role because right now the friction value on this cube is 0.5, and the friction value on this one is 0.5. In such a scenario in real life, you will have a lot of friction happening. That's why you can select, first of all, the wood piece and increase the friction up to one, and also you can select the metal box and bring the friction up to one. Now if I hit play, notice what will happen. As you can see, it starts to slide really slow on this wood piece until it eventually stops, but it might fall, but there is not enough time. You can also, for example, lower the friction value on the metal box to something like let's say 0.7 and let's see what will happen, hit play, and hopefully it will fall and it won't fall because we also need to lower the friction on the wood piece, 0.7, go back to frame number one. Let's hit play, and it is falling slowly. Let's hope it will fall, and boom, it fall down. So in this situation, up until this point, all we're having is a friction because it is just two objects that are sliding on each other. There is no bounciness. But the moment this metal box will fall from this wood piece, now we're talking about bounciness when it will collide with this sponge, which we set the value for bounciness to 0.5 if I increase it to one and go back to frame number one and let's hit play. And when it will fall, it should bounce a little bit more. In this situation, the effect is not that clear because this metal box is really heavy. We're talking about 100 kilograms. That's why it is hard for the sponge to actually throw this metal box up in the air. If I wanted to, I can change, for example, the value for bounciness to a higher value, and that should technically make the cube jump a little bit more in the air once it collides with the sponge. But keep in mind that that won't be realistic because metal is not bouncy, so this value should be set to zero. The last two options we're going to talk about are the dynamics, and you will have here is dampening translation and dampening rotation. The word dampening means slowing down. When we say dampening translation, that means that we will dampen or slow down the movement or the translation of a certain object or the rotation, which is self explanatory. It is a way to tell blender the rate of slowliness, let's say, of a falling object or technically any object. Also, it is important to mention that this doesn't just work when two objects are colliding or something. No, these settings will affect the entire movement or the entire way Blender is calculating the simulation for that object. For example, if I hit play, notice how will this metal cube fall? Now if I increase this dampening to up to one, for example, which is an extreme value, and now if I hit play notice how it will fall, it will start falling gradually, like really, really slow, which is absolutely not realistic. It's like everything is running in slow motion. Rotation will do a really similar thing. It is just applied for the rotation of the object. Now you might wonder, how are these values supposed to be useful? Wouldn't I want Blender to basically calculate everything? That is technically true, but these options comes really handy sometimes when you're simulating objects that almost doesn't have a weight. For example, if you try to create a simulation of balloons, Blender will probably will not be able to calculate how everything will behave because the mass of the cube is almost non existent, let's say, in the eyes of blender, of course, because it is really, really lightweight or, for example, a paper. So this option can help you to create that sense that, okay, this balloon is really lightweight, so it won't fall that fast. When you increase this value, you can see how imagine if this was a balloon, it will start to fall slowly, just like in real life. And this is how these values can be useful for the dampening translation and rotation. 6. Rigid Body World: Rigid Body world. Hey, everyone. Welcome back. In this video, we will dive into the Rigid Body world settings. You can find these settings in the scene tab. Adjusting them doesn't just impact a single object. It changes the overall rules for how the simulation is calculated. So let's jump into blender to learn more. Hello, and welcome back. And this is one of the scenes we already saw in a previous video. And as I mentioned, in this video, we are going to work or explain the settings related to the rigid body world. I have no rigid body systems applied to all the different objects, so I'm going to start, first of all with the sphere. Jump to the physics step, add a rigid body to it, and for the shape, I'm going to set it to sphere. Same thing for the blue ball, add a rigid body to it, and change the shape to sphere. For the wood pieces, they will be passive objects, change it to passive, and for the shape, make it a box, and same thing for all the different ones. They should be passive objects. And to simplify the calculations, you can always turn them into boxes. And lastly, same thing for the floor, add a rigid body to it, and it should be a passive object. Now, if I hit play, notice what will happen. This is our simulation. Next, I'm going to jump to the scene properties tab, and from here, we can change a couple of settings regarding the rigid body world. First of all, you have gravity, which as the name states, it will control the gravity of our scene. By default, it will be on the Z axis -9.8 meters square, which is the exact same value of gravity on planet Earth. But you can play with these different values, and you will get different results if I jump to frame number one, and let's say I make the gravity weaker minus two, for example, and I hit play, these two balls will start to fall way slower. Notice what will happen if I hit play. You can also jump to frame number one again and let's say I want the gravity to also be applied on the X axis, something like two, hit play. And as you can see, the objects right now will also fly along the X axis. If you're going for realism, then probably you want to keep all of these different values to default values just like in a planet Earth. But I think you can see how these values can also be useful sometimes if you're trying to create something stylized or something that is not physically based on the physics of Earth. Next, you have the step called simulation, which is just a fancy way to tell blender what is the range of simulations. By default, blender will render the entire frame range. For example, my current range is 1-250, Blender will cache or simulate the entire timeline. If you want to only simulate a certain range, you can specify that from here, and now we jump to the most important this video, which is the rigid body world. First of all, you will have collection, and collection is a collection that contain rigid body objects that are participating in the simulation. And for the constraints, right now, I have no collection for the constraints, but in case I have, or I created a collection that is meant for constraints, basically, those objects will be contained inside a collection right here. I can specify it. Next, you have the speed, which is just a way to control the speed of the simulation. If I set this to the simulation will be twice as fast. If I hit play, the simulation will be faster. If I type 0.5, the simulation will be slowed down by half or 50%. This can give you a similar effect to the gravity. I'm going to set it back to one. Next, you will have this check box called split impulse. I would highly recommend that you always keep this option off because it always causes blender to crash in my experience. If you jump to the blender manual, you will find a really confusing definition. It says that split impulse enable or disable, reducing extra velocity that can build up when objects collide, lowers the simulation stability a little, so use only when necessary, limits the force with which objects are separated on collision, generally produces nicer result, but makes the simulation less stable, especially when stacking many objects. To be absolutely honest, I don't understand exactly what this option does. I tried to look for some resources on the Internet, but I didn't honestly find any good explanation. Next, you will have this option called substeps per frame, and this is a really important settings. Right now, my frame rate, if I jump to the output properties, it is 24 frames per second, which means each frame will last 1/20 4 seconds. The substeps per frame is a way to tell blender the number of simulation steps taken per frame, which means how many times you want a blender to calculate the position of the different objects. Right now it is set to ten, which means that blender will calculate the position of the different balls in our situation ten times per frame. And next you will have the solver iterations. The solver in blender is the algorithm responsible for calculating the simulation. So the solver iterations, it is a way to tell blender how many times to run those algorithms per substep. So one way to think of this, Hey, blender, for each frame, try to calculate the position of the different balls ten times. And for each one of those substeps or for each attempts of trying to calculate the position of the ball, do ten iterations, which means calculate or run the algorithm trying to predict the position ten times. Of course, I need to emphasize that yes, I'm saying position, but this goes for all the different interactions, rotation, objects colliding and all of that. Next, we move on to the cache tab, which is also just as important. You have the simulation start and the simulation end, and this is a way to tell blender which areas to cache. And right here, Blender will tell you some information about the caching process. So 160 frames in memory, 44 kilobytes, and the cache is outdated, which means I didn't update the cache. The first option you will have is BC which literally will bake all the different simulations, so you won't lose them in case you close blender or any of. Calculate to frame, we'll calculate the simulation up to where the cursor is. For example, to frame 160 right now. Current cache to bake. Current cache to bake, imagine if I hit right now play and the simulation is playing. If I click on this option, Blatter will transform all the things that I cached right here into an actual bake. Bake all dynamics. As the name states, it will bake all the different physics in your simulation all at once. Delete all bakes. That will delete all the bakes you did before. And the last one, you will have update all to frame, which will update the bake you already have. Most of the time you will find yourself using either the option B bake all dynamics when you finally finished your scene. And the last tab, which is field weights, the best way of how I can explain it is that same as other physics dynamic systems, rigid body simulations in blender are also influenced by external forces effectors. For example, you can specify from here how much you want to gravity to affect the simulation. This all option basically will change the overall or all the different settings all at once. You have vortex, magnetic, harmonic, charge, and all of those different things. Basically, these are the stuff if I go Shift A from here and I jump to force fields, you will have all of these different one are ways that you can also control your simulation. For example, if I add wind, that might affect the position of these two balls. So from here, let's look for wind. I can change how strong the effect of the wind is. This is also an advanced option since most of the time, in case, for example, you added some wind, you can probably change the settings of that wind instead of playing with the strength from here. So most of the time, this step isn't that useful, but it can come handy in certain situations. This is basically it for all the settings related to the rigid body world in blender. Next, we are going to start doing some practical exercises. 7. Galton Board: Gltenbard simulation. Hey, everyone. Welcome back. This is the first exercise, and we will be working with a Galten board. A Galtenbard is a device where beads are dropped from the top, interact with the pegs as they fall, and distribute themselves to form a bell curve. It's a fun way to put all the concepts we talked about into practice. So, yeah? Dive in. Hello and welcome back inside of Blender. This is a fresh blender scene, and we will be doing everything here. We will append a collection from another blender file, and we will create the simulation here. I'm going to pick a general for the template. I'm going to hit A, X, and delete everything because I don't need neither camera. Nor the default cube. I'm going to change a little bit the setup of blender. I'm going to hit T to hide the sidebar. I'm going to also hide these tools by going to header and show tool settings. I'm going to expand this a little bit. And because I think it is useful, I'm going to enable the screencast keys, which will allow you to see the shortcuts I type right here. And this is the basic Blender setup I'm going to use for this video. Now we need to create this Galtenbard simulation. I'm going to go to File append. And in the resources that comes with this course, you will have this option called A Galton board. If I double click on it and go to collection, you will have this collection called Append M. This collection contains all the different other collections. So just click Append me and you will have three different collection inside this one. There is one called frame. I'm going to move it out. Beads and pegs. Now you can delete this collection and the ependymy collection. So our entire scene is formed by three different collections that I want to explain each one is responsible for. I'm going to jump to the rendered view, and by default, you won't be able to see anything. That's why I can uncheck Scene world and pick one of the HDRIs that comes with blender, and this should give you a better view on what's happening. First of all, you have the front glass, this one right here. I'm going to hide this bad boy right now because it is obscuring the view, but it is important that we have it so that the beads later don't fall in front of the entire structure. I'm going to hide it. Next, you have the metal body, which is the one responsible for basically being the collision object for all the different beads that will go through here and then fall down and the wood back, which is kind of self explanatory, it is the back of the Galton machine. Next, you have the beads, which is this small sphere right here, we'll be adding a lot of them. I probably at the end, we will have around 600 ish of these beads, and I will show you how to create them. And finally, the pegs. And the pegs are these bad boys right here, which are responsible for colliding with the beads, so they will guide them at the end to fall right here, and they will form this bell curve. So this is a small breakdown of all the different objects in this scene right now, and let's get into the fun part which is creating the simulation. The first thing I'm going to start with is by adding a lot of different beads. This will be really simple. All you need to do is to select the bead, and let's add a modifier to it called the array modifier. Which will allow you to duplicate an object a certain number of times. I'm going to duplicate it on the X axis for now, so this should stay one, or actually let's make it 1.5. So I will have a small gap between the different beads and increase the number to your heart's content. For example, 28 seems to be a good number. Add another modifier array, and right now we want to array them on the Z axis down. So make sure to change this back to zero, and we want them to go like this, which is the negative Z axis. So do -1.5 and increase this number to I don't know. Let's say 24 seems to be a good number. And next, we need to apply all of these different modifiers, because this geometry right now doesn't exist. It is generated using the array, and if you want to add a rigid body system to it, each one of these Bs should be its own separate object. So the first thing that you need to do is to apply each modifier, apply apply. Now if I hit tab, each one of these beads it's its own mesh, but we want them to be their own separate object. So how can we do such thing? This is actually really simple. Make sure to hit tab, hit A to select everything, hit P for separate, and you will have here an option, separate by loose parts, which is just a fancy way to tell blender that, hey, blender, each mesh or each part of my object that is not connected to any other geometry, separate it. And since each one of these beads is not connected to any other bead, when I click this option, Blender will separate each bead on its own. Click on it and wait for a second. And boom. Right now, each bead its own separate object. If I hit tab again, and these are the different beads separated. If I collapse this collection, you will see that we have 672 beads, and still, there is a small problem in these beads, which is the center of all of them is still here. They all share the same exact center, which is the origin point of the first bead that we created. In blender, an important concept that you need to keep in mind is that it is highly recommended that the origin of the objects that you're trying to simulate should ideally be in the center or the origin of each object. That's why I'm going to double click on this collection to select it all right mouse button. You will have an option for set origin and choose origin to geometry. Right now, the origin of each bead will be in the center of that bead. Now we can move on to adding the rigid body systems to all the different objects. I'm going to start with the wood back, so select it, jump to the physics step, add a rigid body to it. It should be a passive object, and for the shape, change it from convex hole to box. You will notice also a small problem, which is that for whatever reason, the box of the rigid body is somewhere here, and this goes back to the point I was talking about, which is that the origin should be in the center. That's why I make sure to select this back wood or wood back right mouse button set origin to geometry, and everything will work fine. Next, we move on to this metal body, add a rigid body to it, change the type from active to passive. We don't want it to move. And for the shape Pick mesh. Convex hole will be terrible. It won't give us the result we're looking for. There is also another problem in this object, which is, if I hit N and jump to the item properties, you will notice that the scale is not one. The scale is not applied, and that's also an important thing to keep in mind. It is highly recommended that whenever you're trying to create simulations in blender, to have a consistent scale. That's why it is a good practice to apply the scale for all the different elements that will be part of the simulation. Select this metal body, Control A, and apply the scale. I'm going to hit to hide the side bar, and let's move on to the front glass, which is not visible right now, but also it is important to add a rigid body to it, add a rigid body. It should also be passive and for the shape, change it to box, and same problem. The origin point is in the bottom. We need to turn it into the center so that the box of the rigid body will look right, select it, right mouse buttons at origin to geometry. And hide it. This is how you can add a rigid body system to the frame. I think it was simple. Now let's move on to the beads. I'm going to select my first bead. Let's add a rigid body to it, a rigid body. I'm going to keep everything the way it is, and I will just change the shape from convex hole to sphere. And right now, you need to do this exact same thing for each bead on its own. That's why simulations are time consuming in case you're wondering. Hope it should be clear by now that I was joking. But in general, you can always select all the different objects you have and make sure that you select the object that does have the rigid body system. Lastly, so it will be the active selected object. Next, go to object and then rigid body, and you will have an option for copy from active, which is just a fancy way to tell blender that, hey, for all the different objects, copy the rigid body system from the active object, and the active object is the last object that you selected, which is the yellow one which is the one that does have the rigid body system added to it. A fun way actually to remember this shortcut is to go to object, B, and then next hit F, copy from active, which I always like to remember it as boyfriend, B F. So if I go while selecting the object that does have the rigid body system added to it as an active object, go to object B. And then F, each one of these beads right now will have its own rigid body system added to it. It is that easy. And the last part that we need to add a rigid body also to it are the pegs right here, this should also be simple. I'm going to select, for example, the first peg. Let's add a rigid body to it, and it should be a passive object, and let's change the type to a cylinder. And it is looking a little bit weird because Bolano doesn't understand the rotation of this cylinder. A way to fix this, actually. I'm going to hit Tab to jump to the edit mode, hit A, to select the entire mesh, R X 90. This object right now is rotated on the x axis 90 times, and by the way, this will happen to all the different beads because they all share the same exact base mesh. Next, hit Tab again to leave the edit mode, hit R X and 90 again to cancel all the different transformations, but that will only be applied to this one. So hit Control Z to cancel that and make sure to select the entire collection called not beats, called PEGs. Change this from medium point to individual origin. R X 90, and this will rotate all the different pegs all at once. So right now, they all have the same exact rotation. And the really nice thing is that the shape of the rigid body system will be a cylinder that does follow the actual cylinder, which is nice because that will save a lot of memory. The next thing, we need to apply this rigid body system to all the different pegs, select the entire collection and make sure that the one with the rigid body system added to it is the active one. It is the last selected one. Go to object B, F, and each one of these right now, have its own separate rigid body system added to it, which is exactly what we want. And now, if I hit play, I will have my simulation. So I'm going to hit one from the number pad to jump to the front view, and let's hit play to run the simulation. And let's hope everything will work fine. Hit play. And the simulation will go haywire. So what is the problem of all of this? When I first created the scene, I spent a lot of time trying to figure out what's wrong, and I know what's wrong. The thing is, if I, for example, pick one of these different objects, let's say, the biggest object, which is the metal head or the metal, not the metal head, the metal body, and I hit N, these are the dimensions of this object. It is 1.38 meters tall. Is actually for a Galten machine that's already big. But for blender, all these different objects are really small. You have this big object and these beads are really small, and blender is not good at all when it comes to calculating stuff for tiny objects. The solution is actually really simple. I'm going to hit A to select everything, and there is a problem, which is that make sure also to show the front glass because it won't be selected if you do A while it is hidden. Hit A to select everything. Hit S for scale, and I'm going to type ten, which is just a fancy way to say, Okay, something is wrong. I didn't select all the objects. Hit A. Same thing for this one. Okay, everything is selected. We're good. Jump to frame number one. Hit S and type ten to scale everything by ten. But why? Hmm. Okay, this is not looking good, but why? Ah, Okay, because I didn't change the individual origin, I need to change to median point, my bad. Change this to medium point, and right now, if you hit S, you will scale everything proportionally. So hit S and type ten, which means that we will scale the entire scene by a factor of ten. Next, hit Control A and apply the scale, and you will have this really long message of problems that blender will show it to you. So we need to solve that, okay? Hit to hide the sidebar, and I'm going to collapse all of these different collections because I was trying to know what's wrong. Let's collapse it, and we will do it object by object. But don't worry. This will be really fast. So first of all, let's select this bad boy, Control A, and apply the scale. Same thing for the metal body, Control A, and apply the scale. Same thing for the glass, Control A, and apply the scale. We're good. I'm going to also hide the front glass because I don't need it. For the beads, select the entire collection by double clicking on it, Control A, and apply the scale. Good. And for the pegs, double click on it, Control A and apply the scale, and you will have this very long message. The main reason causing this problem is that all of these different objects share the same mesh data. So select, for example, one of them, hit Control A and apply the scale. Blender will tell you that, hey, this will turn it into its own separate mesh. So I'm going to hit Cancel, and let's select them all shift like this. And then this one as an active object, Control A and apply the scale and this is how it works. Select them, make one of them the active selected object and apply the scale. It is that easy. Let's collapse this entire collection because I don't need to see it. So technically, right now, all the different objects will have a consistent scale of one. Let me hit one from the number pad, hit eight to select everything and make sure to show also the front glass, A, J, Z, and move it on the Z axis a little bit up, so it will be above the floor, hit end to hide the sidebar and also hide the front glass, hit one from the number pad to jump to the front view. And right now, we scale everything by a factor of ten. Hopefully everything in the eyes of Blender right now it is big. So when I will do the simulation, everything should work fine. Let's try that again, hit play, and boom. Everything will work fine. I just got to wait for the simulation to end. And there might be a small problem, which is that I don't have a good range for the scene. I might not have enough time for the simulation to end. And yeah, just as I thought. So let's turn this to 400 and simulate again. Okay, the simulation seems to stop at this point. And my guess is that if I jump to the scene properties, rigid body world from the cache, right here, you will have simulation start and simulation end. Make sure to also make it 400. Let's move back to frame 237 and play again. And right now the simulation should end at frame 323, 323. So yeah, now this is our simulation, and it is looking really decent as you can see, also, we're getting the bell curve right here, which is nice. In case you want, for example, also to make the simulation slower, you can decrease the speed to something like 0.5 and let's sit play again, and the simulation right now will run slightly slower so that you can spend more time looking at it if you want, or you want to render slow motion render for this simulation for this gltenbard. You can play with all the different settings as much as you want, but this is the basic idea. In my case, I'm going to leave it back to one because I want it to be more or less based on real life timing. And once you finish polishing your simulation, you can always jump back to frame number one, and you can choose the option to bake all the different dynamics. This will bake the simulation, which means you won't lose any progress in case you close blender and go back to this project. So click on Bake all Dynamics, let's wait for blender to bake everything. The bake ended, and this is my Galtenbard simulation, and that's how you can create. I hope this video was fun. I hope you learned a little bit about how to troubleshoot different problems when it comes to creating rigid body simulations, and I will see you in the next video and also make sure to save your file. 8. Falling Dominos: Falling Domino simulation. Hey, everyone. Welcome back. This is the second exercise. We will be creating a cool domino falling simulation. This exercise will be a fun challenge. You will run into plenty of troubleshooting and get to experiment with different solutions along the way. It's a great way to build the problem solving skills you will need when working with rigid body simulations. So yeah, let's dive in. Hello, and welcome back inside of Blender. Let's pick General and A, X, and delete everything, hit T to hide the sidebar, and let's hide the A toolbar header show tool settings. I'm going to expand this a little bit. Go to file, append. And in the student's project folder, you will have the falling domino scene, double click on it, jump to collection, and pot the dominoes and the floor and append them. This is basically let me just disable the collection for the floor for a second, and I'm going to select the collection for the dominoes, hit the period key to jump and focus on one object. These are all the domino pieces in the scene. I have 36 domino pieces, which is how many domino pieces in a set of dominoes, I think. You won't see all of them all at once because they are over each other because we need to have them like this for scattering them and putting them on a curve. I'm going to also jump to the rendered view and let's check Scene world and let's use, for example, DRI or let's keep it to the default one this time. Let's show also the floor, which will come with its own material, which is a really simple wood material that I have downloaded from the Internet. The first thing that we need to do right now is to create a line of domino pieces that we will make them fall, basically. I'm going to hit seven from the top view and let's zoom in a little bit. I'm going to go Shift A, and let's look for a curve, and let's look for busy curve. By default, you will have this line. You can hit Tab to jump to the edit mode. Let's select this point and hit R to rotate it, and as to scale it a little bit down. So you will have something looking like, so it's like an S curve. Right now, by default, it is inside the Domino's scene, but I don't want it to be there. So hit M to move it to a new collection, and let's create a new collection and call it Dominos line, for example, and create. Next, I want to distribute or create or array the domino pieces along this curve. So how can I do? Well, some of you actually might think of the array modifier, but this is actually a bad idea because the array modifier doesn't have many options regarding the rotation. That's why we are going to use geometry nodes, but I promise you, it will be really simple. I'm going to open this and let's open the geometry node editor, hit to hide the sidebar, and create a new geometry node tree. And let's call it, for example, Domino's line. And let's also enable this magnet, so the nodes will stick to the grid. I want to distribute the domino pieces along this curve. That's why I will start by adding a node called curve to points, and let's put it here. This will distribute points along the curve. And let's say, for example, I want to have 30 for now, 30 points. Next, I'm going to add another really handy node and a famous node called instance on points, which is just a fancy node that will allow me to replace those points I just created using the curve to points by other objects. What do I want to replace them with? Want to replace them with the domino pieces. So just drag the Domino's collection from here and put it here and take the instances and plug it to the instance. And if I zoom in, you will have something looking like so, but it doesn't look right, first of all, because it's like we have the same piece for all the different pieces. We want blender to use random variations for those pieces. This is actually really simple. Make sure to check separate children and pick instances, and each one of these domino pieces right now will be at random. And you can also see that I'm seeing this collection, so just disable it. So now I have this line of domino pieces which is exactly what I want. But there are two problems that I'm going to discuss them right now. If I hit seven to jump to the top view, as you can see, the pieces are not rotated in the right way. I want them to be rotated a little bit like this. Okay? So how can I do such a thing? This is also simple. If I move these nodes here and look for a node called rotate order or actually a line order. So go Shift A, look for a line rotation to vector, so just pick this node. Put it here and take the rotation. I'll plug it to the rotation and take the rotation, I'll also plug it to the rotation and you will have this result, which is exactly what we want. Now looking at this, I think I can add more instances. Let's try 40. This seems to be decent. I think I can even make it 50, which will make it look even better. Next, we need to turn this geometry into actual geometry because right now it's all just in geometry nodes and all of that. So at the end of your note tree before the group output, go Shift A and add a node called realize instances, which will turn the instances into actual geometry. Next, while you're selecting your By curve, go to object, convert and convert into a mesh. So now if I hit Tab, as you can see, each piece, it's its own separate mesh, and we need to separate them. So hit A to select everything. Hit B for separate, and you will have an option for separate by loose parts, which is the same exact thing we did for the beads, if you remember in the Galtenbard video, separate by loose parts. Each domino piece is its own mesh right now or actually its own object. Next, they are clipping down in the floor. So if I select one of those pieces and hit N to open the side bar to see the dimensions, you will notice that the dimensions are 0.1 on the Z axis, and this is basically in the middle. So if I want to move them up, all I need to do is to move them on the Z axis by a factor of zero point 1/2, which is 0.05. Select the entire dominos line, hit J Z 0.05, and they should be on the floor right now. I'm going to hit to high the sidebar and let me collapse this down. And this is the line of domino pieces that we will make fall. And the last thing I'm going to do since I selected all of them, the origin of all the different pieces right now is right here, which is not what I want. So I want each piece to have its own origin and the center. So click on the right mouse button, set origin and origin to geometry. That's how I will leave it for now. An important thing I will need to mention from now, maybe later maybe since I want the pieces to fall based on their base, I might need to move the anchor point or the origin point down. But for now, let's see how it will look like, and later on maybe we'll change it. I'm going to hit Control Z to remove this Ti that I just drew. A since I want to make the domino pieces fall by a sphere, I'm going, for example, to jump to the first domino pieces, Shift S and cursor to selected, Shift A, and let's add a mesh called UVsphere I will have this giant sphere right here, so hit S to scale it way way down, zoom in a little bit, scale it even more to something like this. And you can hit three to jump to the side view or one, and let's move it around here on the floor and Shift C to resist the position of the three decursor. Hit seven to jump to the top view. Let's move it here, and I wanted to push the first domino piece. So let's start creating right now our rigid body system. Okay? First of all, I'm going to start with the floor, which I'm going to move outside this collection called collection and same thing for the dominoes and delete this collection. Like the floor, go to the physics stab, add a rigid body to it, and change it to a passive. Next, we move on to the domino pieces. Let me select the first piece, add a rigid body to it, and let's make it an active object. And for the mass, I'm going to lower it to 0.1. And for the shape, let's make them box. And it looks all weird, but we will fix that in a second. Next, I'm going to select the entire collection and make sure that the active selected object is the one with a rigid body system added to it. Next, go to object B, F, and each one of these pieces right now will have their own separate rigid body system added to them. But there is a problem with the rotation. I was thinking that maybe I can solve this problem doing the same thing I did for the pegs, but I don't think so since each one of them does have a different box around it. So I think this is one of those situations where I will need to change the rigid body system to actually work based on the actual mesh, and I need to go to object, rigid body, and copy from active. So each one of them will be based on the mesh, which probably will cause the simulation to be slightly heavier and more unstable. But I think we'll be fine in this situation because still the shape is more or less pretty simple. For this sphere, I'm going to hit N and I need to apply the scale. Control A, apply the scale. Let's add a rigid body system to it, okay, it seems like it already does have a rigid body system to it because when I select the entire collection, apparently the sphere is also inside this collection. So just for clarity reasons, I'm going to hit M, new collection, and I'm going to call sphere, and let's collapse this dominos line. And for this sphere, let's see what does the object or the physics part does have. I'm just going to change the shape from mesh to sphere. And for the type, let's keep it at active. And since I want to move it to push the first domino piece, I'm going to check the option for animated because it will be animated using the animation system, not the dynamic system in blender. I'm going to jump to the timeline where is the timeline. For the first keyframe or for the first frame, I'm going to hit K and let's insert a keyframe for the location. Next, move it forward. Let's say to frame number say to frame number ten. Okay, for whatever reason, everything exploded. So let's jump to frame number 20. What about frame number one? Okay, since the simulation is playing, I'm going to disable the sphere for a second, and let's see if I hit play, what will happen. Okay, everything will explode for whatever reason. Part of me thinks that it's because of the origin point. So let's select all the domino pieces, it tap to jump to the front view or actually hit tab to jump to the edit mode, hit A to select everything, J, Z, and move them on the X axis by 0.1. This is not looking good. What I'm trying to do is to move the center of each domino piece in the bottom. But each one of them does have a really weird way of how the center is located. So let's just move here, set origin to center of mass on the surface, three to jump. Still, some pieces does have weird placement. Like for example, these ones right here. Like this one, for example. So how can we fix this issue? Three. Let's select all of them, set origin to the volume. And yeah, this algorithm is doing way better job at moving the center of the different objects. Hit one to jump to the front view, tab, A, select everything JZ and move them so that the center will be in the bottom, just so you don't have to be precise. Just make sure it is around the bottom of each object. Let's say something like this. Next, I'm going to head JZ and move them down. To be almost on the floor, and this should technically make the simulation more stable if I hit play, and they explode again for whatever reason, so we need to figure out a way to fix this. Okay. I'm going to hit JZ and move the plane a little bit down, and I'm going to select all the domino pieces and make sure this one is active. Let's change the shape from mesh to convex hole, okay? Object, rigid body. Copy from active. So each one of these will have a convex hole shape, which is simpler for blender to calculate. Hit Space bar to play this simulation. And this is way, way better, I think. Yep, this is exactly what we want. So move back to frame number one, select the plane, l J to reset the position. If I hit play, everything is super stable, which is exactly what we want. Next, hide the sphere and hit seven to jump to the top view. Make sure I frame number one, we already added a keyframe. So jump to frame, for example, number 20, J, and move it to push the first domino piece, K, and insert a keyframe for the location and make it a linear by hitting T and choosing linear for the keyframe interpolation. And now let's hope everything will work fine. Okay? If I hit play, Okay, it is not looking good. It is maybe because we changed the origin earlier. So let's select all the domino pieces and do set origin set origin to geometry. And what should happen? Now, let's see hit play. No, this is a bad idea. So let's do Control Z. And for the mass, let's see the physics step, maybe we can make them slightly lighter, but I don't want to do that because that might cause the simulation to be unstable. What I'm going to do instead is a small experiment, which is to disable the sphere, and for the first domino pieces, I'm going to hit R x to rotate it on the X axis. And let's say I want it to fall on this one, okay? Just like so. On frame number one, if I hit play, Nope. Somehow it looks like they bounce or something like that, which I don't know why it's happening. So I'm going to reset the rotation, and I'm going to do something I already did, which is select all the different domino pieces, set origin to the center of mass or volume. Let's unhide the sphere again and hit play. And yeah, now it's working way, way better. So by setting the center to the center of mass, we solve the problem of them wiggling on their base because this is way better. And when this sphere will hit them, boom, they fall. And this is actually looking really sick. So let me just do this. This is really nice. The last thing you can do is probably jump to the Physics tab, for example, which is in the scene tab, and let's make it, for example, 0.5 in terms of speed, so it will run slower so we can spend more time watching it. And this is really sick. Now, of course, you can spend some time trying to render the scene maybe add a camera that will follow the domino pieces falling and all of that. You can play with all of that to your heart's content. The last thing I'm going to do is to jump to the case tab and choose the option for BCO dynamics. And yeah, this is it for how to create a falling domino simulation. As you can see, it is a really fun exercise, and the result is really nice. And you can probably create something more creative than what I just did here. Maybe you can distribute them so they will reveal a certain shape. There are a lot of things you can do with domino pieces. This is basically it for this video, and I will see you in a future video. 9. Rigid Body Constraints: Rigid body constraints. Hey, everyone. Welcome back. An important concept in simulations is constraints, and constraints define the relationship between different objects. These settings are especially useful when dealing with objects that are made up of different materials or pieces or when you want to create specific interactions between objects, this video will be slightly longer because we'll be exploring each type of constraints in detail. So without wasting any time, let's learn about constraints. Hello and welcome back to this really basic blender scene where we will learn about the fixed constraint. We have a really basic scene where we have this floor, a bunch of wood obstacles, and this hammer on top. The goal of this video is to learn how to make this hammer fall in a realistic way. So the first thing I'm going to do is to add a rigid body system to all the different obstacles. Just select one of those wood boards, jump to the physics stab, add a rigid body to it, and change it to passive. And for the shape, I'm going to turn it into a box. Now we need to copy this rigid body system to all the other objects instead of doing it manually. While holding Shift, select the rest of the objects and make sure that the active one with the yellow outline should be the active selected object and the one you selected the last. Next, go to object BF and this will copy the rigid body system from the active objects to the rest of the objects. This is a basic workflow that we've been doing from the beginning of the course. Next, we need to make this hammer fall in a realistic way. And right now there is something important I need to mention, which is that hammer is not one object. If I open the collection called hammer, you have the handle, the wood handle, and you have the metal head, okay? So each of them is a separate object. And that's a realistic way of how to do it because these are two different things that are joined together just like in real life. So how can I make this fall in a realistic way? The basic instinct or some of you might suggest is to add a rigid body to this one, and let's say, since it is metal, let's say 30 kilograms, and for the shape, I'm going to turn it into a box. And for this wood, handle, I'm going to add a rigid body, keep it as active, for the mass, keep it 1 kilogram, and for the shape, also change it to a box. And now, if I hit play, hopefully everything will work fine. So let's set play to see what will happen. And yeah, it doesn't work the way we want it. They fall in a really weird way and they get separated from the beginning of the simulation. So why is that happening? Well, because blender doesn't know that both of these two objects are joined together. So what's the solution? The easiest solution that also some of you might suggest is to join both of these two objects, the handle and the head. I'm going to remove the rigid body from both of them for a second, select both of them, and then do Control G to combine them. And now I can add a rigid body to it. Let's say the total mass will be 31. If I hit play now, it will fall this way, which is not necessarily bad. You can do way worse than this, but still the hammer maybe will look fine. But with other objects that are slightly more complex, this will look terrible. The main reason for this is because, for example, this hammer, the head should be way heavier than the handle. But when we join them together, everything will have the same mass. Blender will treat the wood handle. Same way we'll treat the metal head, and this is not realistic. That's why, especially in exaggerated examples, for example, imagine this wood handle should bounce or it is a really soft material, and this metal head is metal and it is heavy. So you need to simulate for both of these materials at the same time. But when you combine them or join them, Blender will treat them as one object that is created from the same material, and this is not what we want. This is where constraints comes into play. I'm going to hit Control Z to cancel the joining movement that I did and also remove the rigid body system that I just added, and we're back to each one of them being its own separate entity. A rigid body constraint is a way to tail blender the connection between two objects. I will always go back to this definition because you need to always remember it. A rigid body constraint, a way to tell Blender how to join two objects, or what is the relation joining two objects? And another question you will always need to remember is to always ask yourself when you're trying to do rigid body constraints. What is the relation between these two objects? I'm going to ask you now, what is the relation between both the wood handle head, and the answer should be really simple. They should stick together. They are fixed. They don't move in relation to each other. And there is an exact constraint for this one that is called the fixed constraint. Before I explain how to do that, I'm going to select the wood handle and add a rigid body to it. For the mass, keep it the way it is, and for the shape, I'm going to turn it into a box, select the metal head, rigid body, active for the mass. Let's make it 30 kilograms, and for the shape, I'm going to turn it into a box. And now comes the rigid body constraint, which is this button right here. Something. You can always add rigid body constraints on the objects, but it is highly, highly recommended that the best way to add rigid body constraints is to add them using empty objects. Here's what I mean. I'm going to select this metal head and hit Shift S and cursor to select it to move the three Dcursor in the center of this hammer. The main reason I'm doing this is to just add an object right there. Next, I'm going to go Shift A, and let's add an arrow. I will have this empty object, which is just a very simple arrow. Next, I'm going to add to it a rigid body constraint. For the type, you will have all of these different ones, and we will explain each one of the the first one that we care about is the fixed, and a blender will tell you glue rigid bodies together. So it is a way to combine or glue two objects together, even if they have different rigid body systems added to them, which is the exact situation of this hammer. So I will keep it at fixed, and you will have here objects where you need to select the two objects that are joined together. So the first object will be the wood handle and the second object will be the metal head. And now you might wonder, but, hey, why are you using an eptune object? Here's how you should always think about it. The empty object is where the relation is happening. When I put the rigid body or sorry, when I put the arrow in the center of this metal head, that's where the relationship between those two objects is happening. But it is important that I mentioned, I'm just saying that to explain it to you. I can even move, for example, this empty object, and the relation will stay the same. The location of this empty object doesn't matter in this situation for the fixed constraint. So in general, we use empty objects as holders for the information that defines the relation between two objects. So now if I go to frame number one again and hit play, notice what will happen. Now the hammer will fall in a way more realistic way because when we join them, right now, the head will have a certain mass and the wood handle will have a lighter mass. And that way, we can have a really realistic simulation. So this is it for the fixed rigid body constraint. Whenever you find yourself trying to glue two objects together, use the fixed constraint. Right now, let's talk about the point constraint. The point constraint is a way to link two objects in a way that will allow any kind of rotation around the location of the constraint object. You can think of the point constraint as a metal rope or a metal bar that connects both of them, and in one end, it is allowed to rotate. For example, it can rotate around this point, but from the other side right here, it is welded. This cube will be able to swing back and forth and all the different directions, but it won't be able to rotate, for example, around the center right here. Meanwhile, this metal bar will be allowed to rotate around here. That's how you should think of the point constraint. I'm going to hit Control Z to remove all of my garbage drawings, and let's start creating this constraint. Let's add a rigid body to the support and make it a passive object and for the shape, turn it into a box. And for this metal cube, add a rigid body to it, it should stay as an active object and for the shape also change it to a box. And now we can move on to creating the constraint. Something I always mentions is that whenever you find yourself trying to create a rigid body constraint, I would highly recommend that you create them using empty objects. So now we should ask ourselves if we were to connect both of these with a metal R, where should it rotate around? I want it to rotate around the center of the support. I'm going to hit Shift S and cursor to select it, and the main reason I'm doing that is to move the three Dcursor to the center of the support. So when I add the arrow, it will basically be added right there. Go Shift A, arrow, rigid body constraint, change the type from fixed to point. And if you hover over it, you will have the definition constraint rigid bodies to move around common pivot point. So select point. For the first object, you can select the support. For the second object, you can select the cube. If I hit Play, nothing will happen at first, but if I go to frame number one, I'm going to select this cube and then hit J to move it, and now hit play. Notice what will happen. Cube will start rotating or start pivoting around the center where the arrow is. If I move the arrow by hitting J, for example, and moving it here, notice how it will rotate. Right now, it will start rotating around the center right here. I'm going to go back to frame number one right now, and while you're selecting this cube, hit l J to resist the position, J Z, and let's move it. For example, 5 meters up in the air. But in my situation, let's say I also want the pyramid to rotate around this cube. While you're selecting this cube, I'm going to hit Shift S, cursor to select it. To move the cursor there, shift A, arrow, add a rigid body constraint. It should be a point for the first object, it should be the cube and for the second object, it should be the pyramid. And I also need to add a rigid body system to the pyramid. Rigid body should be an active object, keep it the way it is. And for the shape, is there a cone, we can choose cone, but it doesn't look right because it is from there. So yeah, let's keep it at cone. It's not a big deal. And now if I hit J and move it here, notice what will happen. Both of them will start rotating in this weird way. Actually one thing you can do, you can select this empty object, the second one, shift select the cube, control P to pair in them, and choose the option object. And now this empty arrow will follow the cube, and since it is hooked to this constraint controlling the pyramid, notice how everything will look like at play, and you will have something looking like so. This is the point constraint. Think of two objects that are connected with a metal bar. From one side, they can rotate, but from the other side, it is welded, so they can't rotate. And the end where the metal bar can rotate is where this empty object is located. Hello and welcome to the hinge constraint. As the name states, it is a way to rotate one object around one other. There will be no movement or translation, just pure rotation. In our example, we have the cylinder, this lever, and this lever. And what I want to do is to make this lever spins around or rotate around the cylinder, and this lever will rotate around this other lever. On a point somewhere right here. So how can I create such a thing? Well, this is simple. As usual, if you want to create a constraint, I would highly recommend that you create it using empty objects or arrows. In my situation, I'm going to go Shift A, and let's look for arrow. By default, it will be added in the center of the scene where the three Dcursor is, which happened this time to be the same exact center of the cylinder, which is exactly what I want. I'm going to hit S to scale it up. This won't change anything. I'm just doing this to make everything clear. I'm going to select the cylinder let's add a rigid body to it. It should be a passive object and for the shape, turn it into a box. Or, actually, no, you can turn it into a cylinder. Next, let's move on to the lever, which is this bad boy right here, rigid body. It is an active object, and for the shape, let's make it a box because it is way, way simpler. Now we can move to the constraint, select the empty object, rigid body constraint, change the type from fixed to hinge. And if you scroll down, you can select the two objects. So first, let's select the cylinder. Next, let's select the lever one. Now if I hit play h will work. Why is that? Right here, you will have something called limits angular and you will have a check box called Z angle. The hinge constraint works based on the Z axis of the object it is added to. I'm going to check this box, and right now, this constraint is calculating everything around the Z axis that is right here, which is not exactly what we want. Why is that? Because the axis of rotation between these two object, it is the Y axis. So what you should do in this situation is we need to rotate this empty object so that the Z axis will align with the axis of rotation we want. This is actually really simple. While you're selecting your empty object, hit R X and 90. We'll rotated this empty object around the X axis 90 degree, which will make the Z axis aligned with the axis where we want the rotation to happen. Now if I go to frame number one and hit Play, Blender will crash. This is a common thing you will always find yourself dealing with when it comes to simulations and blender because blender is not that stable when it comes to simulations. Okay, so I rebuild the exact same system we had before, and this time, if I hit Play, notice what will happen. It will rotate around the Z axis of the empty object. These Z angle values will allow you to control how much flexibility or what is the range of rotation? If I turn this, for example, two -90 and this one to 90, go back to frame number one and hit play. This will allow for more freedom and rotation. You can even make this 150, and this will give you more freedom and rotation, and it will eventually go back. Which is exactly what I want. Let's try right now to add the same exact constraint to this one right here, so it will rotate around the other lever. This should be really simple. Let's start by adding a rigid body system to the lever number two, rigid body, change the type from active or actually keep it at active and further shape, transform it into a box. Next, ask yourself, where do you want this bad boy right here, the lever number two to rotate around? Should rotate around an axis somewhere right here. So let's go Shift A, look for an arrow. By default, it will be in the center of the scene. Hit seven from the number pad to jump here and let's move it somewhere around here. This is where I want the rotation to happen. Seven again, and let's put it here. This seems about right, JY, to move it slightly here and always remember when I will add the rigid body constraint, change it to hinge. Everything should be aligned with the Z angle. What is the axis I want to rotate? It looks like this, but the Z axis is pointing up right now. So let's select this empty Rx 90. So now the Z axis is aligned with the axis of rotation I want. The first object is the lever number one, and the second object is the lever number two, and as usual, the order doesn't matter. Now if I hit play, notice what will happen. They will rotate in this really, really nice way. Now, of course, since this empty object is stuck right there, in case I also wanted to move with the lever number one, say they will look connected, I need to select, first of all, the empty, the second empty. Next, shift, select the lever number one, Control P, and parent it to the object. So right now, this empty object will follow this while rotating. If I hit play, you will have something looking like so. The effect is not visible because if I jump to the second constraint, as you can see, I didn't allow for a great level of freedom when it comes to the rotation. I'm going to turn this to -90 and this to 90, and this should give us a way better result. Let's even make it 180. Go back to frame number one and hit play again, -180 here at play. And as you can see, this is looking really sick. So yeah, this is the hinge constraint. It is a way to rotate one object or round another using an axis. The easiest way to remember the rotation axis is to look at the constraint, and you will see Z, which means that the Z axis of the arrow object should be aligned with the axis of rotation you want. Let's move on right now to the next constraint. Hello and welcome to the Sluter constraint. We have also another basic scene. We have this rotating plate which we will make rotate. We have this lever, which is connected to the rotating plate, and also it is connected to this metal cube. And this metal cube will slide inside this canal of the wood piece, and we will actually be creating more than one constraint, and this will be a really fun exercise to understand exactly what the slter constraint do. So first things first, let's make this rotating plate rotate. This should be really simple. I will jump to the object properties, and from here, I'm going to add a keyframe to the rotation on the Z axis. Next, change this timeline from the timeline to the curve or the graph editor, jump to modifiers. Add a modifier generator, which will make this plate rotate extremely fast, and I'm going to make it, for example, 0.05. And now if I go back to frame number one, it will be rotating like this, which is exactly what I want. I'm going to go back to the timeline First of all, we need to create a constraint that connects both the lever and the rotating plate. Make sure to select the rotating plate. Shift S, cursor to select it to move the three decursor there, Shift A, and let's look for an arrow. And we want this arrow to be located in the point of connection between the lever and the rotating plate. I'm going to hit seven from the number pad to jump to the top view, move it around here, also hit three to jump to the side view, J, and let's put it. Around here. This is where both of these two objects will connect. Now, you should ask yourself, what is the relation or what is the type of connection between both the rotating plate and the lever? The rotating plate will be rotating, so we want this to also rotate with it, just like so. So how can I build such thing? Well, this should be simple. By adding a rigid body constraint to this empty object, rigid body constraint, and for the type I want it to be point because as you remember, a point will allow me to connect two objects around one point, which will allow for some rotation. Meanwhile, if I keep it at fixed, that will not allow the rotation to happen. That's why I need to choose point. Nothing will happen, of course, right now because I need to add a rigid body system to both the two objects. Let's select the rotating plate. Add a rigid body to it. It should be a passive object and it is animated, and for the shape, it should be a cylinder. For this lever, select it, add a rigid body to it, it should stay as active, and for the shape, let's keep it at convex hole. You can even choose box if you want something that is more simple. Now if I hit play, notice how it will look, I will fall down. Why is that happening? Because this constraint is not working yet. We need to choose the first object, which is the lever and the second object, which is the rotating plate. And since I don't want both of these two object to interact with each other, I just want to take the rotation of this and apply it to this one. Going to select the constraint or the empty object and you can disable the rotation or actually disable the collision. That will lead to a more stable simulation. If I hit play, notice what's happening. Next, I need to connect the lever with this metal box right here, select the cube, Shift S, cursor to select it. Shift A, let's add an arrow. Where does the connection lies between both the lever and the cube should be around here. So make sure you select to empty, put it here. Hit seven to jump to the top view, and it should be here. Next, let's add a rigid body system to the cube, rigid body, it should be an active object, and for the shape, keep it as a box. Select the constraint or the second empty object. Rigid body constraint also should be a point, disable collision. First object is the cube, second object is the lever, hit seven to jump to the top view, and if I hit play, it will look just like so. This is not what we want. We want this cube right now to slide along this bad boy along the canal. So select the canal, add a rigid body system, and change it to passive, and for the shape, make it mesh. And what is the relation between this canal and the cube? It is a sliding relation. That's why you need to go Shift A, and let's add another arrow, which will be the third constraint between both the canal and the cube. Make sure to select it. And even you can hit F two to call it slider. Rigid body constraint, change it to slider, and you will have X axis right here, which means that this constraint should work along the X axis. In other words, Blender will make the sliding process happens along the X axis of the empty object. So we need to align the X axis along the axis where we want to do the rotation or actually the sliding. We want the scope to slide along this axis, but the X axis of the empty object is pointing this way, so we need to rotate it this way. This should be really simple while you're selecting your slider empty object, RZ and do 90 and this will make the X axis of the empty object aligned with the axis of sliding. Next, you can check X axis. Next, first object should be the cube. Second object is the canal. Maybe you can make these minus two to two just in case. And now if I play, notice what will happen. This cube right now is sliding in the canal. Right now, I want to explain some important concepts that you need to keep in mind. When we are creating this simulation, there are things that you need to keep in mind. Yes, the scene is about creating a slider constraint, but we're also creating other types of constraints. The constraint connecting both the lever and the cylinder is a 0.1. Same thing for the constraint connecting the lever and this cube, it's also a point. That's why it is important to always ask yourself, what is the relation between both of these two objects. You need to go sequentially and define the relationship between each two objects. We started with the rotating plate and the lever, we defined it as point. Then we went to this lever and the cube. We also defined the relation between them as a point. And next between the canal and the cube, we also defined it, which is a sliding constraint. Should always define the relation that is connecting two objects that will directly interact with each other. The rotating plate and the lever, they interact directly with each other. That's why we created a constraint. Meanwhile, this lever and this canal, they don't interact directly. This cube and this canal, they are interacting directly. That's why we created a constraint for them. You should always define for blender, the relation between two objects that are interacting directly when creating these sort of rigid body constraints. So yeah, this is it for the sliding constraint, and I will see you in the next one. Hello and welcome to the piston constraint, which is really similar to the slider constraint. The difference is that a piston permits translation along the X axis of the constrained object, and it also allows the rotation around the X axis of the constraint object. So the really nice thing about it is that it is a combination of the freedom of the slider constraint and also the hinge constraint. So it's like it is combining both of them. I have this really basic scene, and the only thing I did is that I created this small canal, and I added to it a couple of keyframes, so it will swing back and forth, like so. I also have this metal cylinder, which is this weird shaped cylinder. And what I want to do is to make it slide along this canal. So let's start doing that, and I will show you later the obstacle. First of all, I'm going to select the canal. Let's add a rigid body system to it from the physics stab, rigid body. For the type, it should be a passive object and it is animated. I'm going to keep the shape set to convex whole. Next, let's move on to this metal cylinder, add a rigid body to it. It should be an active object, and for the shape, make it mesh. Now, by default, nothing will happen, and everything will explode. So what I want to do is to right now create the constraint I want. Where should be the location of this constraint? Well, the thing that makes the most sense is in the center of the cylinder, the metal cylinder. Shift S, cursor to selected, Shift A, and let's look for an arrow, add the rigid body constraint to it. It's not visible yet because it is too small, so S and let's skate it by a factor of six. So now everything is visible, and let's change the type from fixed to piston. Right here, you will have the X angle and the X axis. The piston constraint does have a similar concept to the slider constraint, which is that everything will be calculated based on the X axis of the empty object. So the sliding will be along the X axis of the empty object, and also the rotation will be around the X axis. So for example, if both of these two objects were rotated like this, so I will need to rotate the empty object so that the X axis of the empty object would be aligned with the direction of sliding and rotation. Let me go back to the constraint. You can check X angle and X axis, and let's make this minus ten to ten because both of these two objects are huge. Next, change for the object number one. You can pick the cylinder, and for the second object, it should be the canal. And now hopefully everything will start sliding like a piston. If I hit play, this will happen. And now you might say, Hey, sin, this is looking exactly like a cylinder. But actually, if I show this obstacle, which is this small cube right here, and it doesn't matter that it will clip with the wood piece. This is not the point, but I'm going to select it and add a rigid body to it and change it to passive. And let's change the shape to box. Now, if I go to frame number one, let's hit play again. Notice what will happen when this cylinder will collide with this cube. As you can see, it will push it away. Let's see it again by going back here. Yep. As you can see, this blue box is pushing the metal cylinder away from it, so it is interacting with it. And this is the rotation component of the piston constraint. The sliding constraint, as you remember, is just about translation along the X axis. Meanwhile, the piston constraint will also allow the rotation of the object along the X axis of the empty object. I hope that makes sense. Of course, you have a couple of more settings right here. You can control how much rotation you want. It's like you define the limits of rotation, which is angular and also you can define the limits of translation on the X axis. If I just reset these to the default values minus one to one, you will notice that the metal cylinder won't slide as much. Let's go back to frame number one and hit play. It barely slides. Let's wait for it to go back, and it will stop here. So by increasing this range, you increase the range of motion of the sliding, and by increasing this value, you increase the rotation. Play again, and it will slide back. Why isn't it not sliding? That's weird. Oh, okay, because I said this to the upper also to minus ten, it should be ten. Let's play again, and everything should work smoothly. This is it for this constraint, and let's move on to the next. Hello and welcome to the generic constraint. I have this wood tube, which I know is not realistic, but it is what it is, and I have this metal object. I'm going to add a couple of rigid body system to them. I will start with the wood the or add a rigid body to it, change it to passive, and for the shape, turn it into mesh. Next, for the metal thing. Add a rigid body to it, keep it as active because I want it to move and rotate and all of that. For the mass, let's make it 20 kilograms, and for the shape, make it a mesh. Now if I had play, this is what will happen. I will slowly rotate and all of that. Okay. Now let's try to add the generic constraint. I'm going to go Shift A, and let's add an arrow as usual, and let's hit S and scale it five times, it will be really visible, and by the way, scaling the empty object will not change the physics. The generic constraint is a constraint which allows the user to clamp translation and rotation of any axis between two selected rigid bodies. What does that mean? So I'm going to select this empty, add rigid body constraint, and let's change it to generic. Right here, you will have limits, and I will go back to these tabs in a second. First object should be the wood and the second one should be the metal. If I hit play, this is what will happen. Somehow it looks like these two objects are not interacting with each other anymore, and this is where the limits comes in. The generic constraint will allow me to clamp the angular and linear limits, which means how much rotation you want on each different axis and how much translation you want in each different axis. For example, let's say I want this metal piece to only rotate around the Y axis. So how can I do such thing? Let me go back to the constraint, and I'm going to close all the angular things or actually disable the Y angle because I don't want to close it. And I'm going to turn these to zero. And this one to zero. So right now I'm clamping the X rotation and the Z rotation to zero, so there will be no rotation along the X and Z. Let's say also I don't also want it to move. And that's what will allow me to do this by closing all of these ones and I'm going to turn them all to zero. What's happening right now is that I'm telling Blender that, hey, for the linear, on the X axis, it is zero, so don't do any movement. On the y axis, it's the same. Don't do any movement because the lower and upper are set to zero. Same thing for the Z axis. So it allows you to control the range of movement. When you check that box, you're telling Blender that, Hey, blender, I want to clamp this property, and once you clamp it, you can pick the values, and if you set them both to zero, this will literally act like a point constraint. That's the main logic behind the generic constraint. It allows you to control how much rotation and how much translation there is. And if you set them all to zero, there won't be any sort of translation or rotation. So now if I hit plane, notice what will happen. I will only have the rotation going on, and of course, the blender needs to go sometimes hey wire, but that's the main concept behind the generic constraint. And I'm not sure if I check or disable collision, that should maybe, okay, this will cause it to be even more unstable. So yeah, this is how the generic constraint works. Next, we will move on to the next constraint, the generic spring constraint. We have these two balls. We have this spring pad, which will make it act as a spring. We also have the floor. First of all, let's start by adding the different rigid body systems we need. For the floor, jump to the physics step, rigid body, it should be a passive object. For the spring pad, add a rigid body, keep it as active and for the shape, make it a box since it is really simple. For the two spheres, add a rigid body, let's keep the weight the way it is and change it from convex hole to sphere, and same thing for this one, add a rigid body with a sphere shape. Now, if I hit play, here's what will happen. Very basic. What we want to do is to make this spring pad, this metal box, act like a spring. So how can I do that? Well, that's simple. We need to add a constraint, called spring constraint. How can we add a constraint? At this point, it should be super clear. Shift A. Let's add arrows, scale them, let's say by a factor of three, just for easier readability. Rigid body constrain. And change it from fixed to generic spring. I will go back to these settings on top in a second. First object should be the pad, and the second object should be the floor. If I hit play, here's what will happen. Everything will fall down. That's not what we want because we need right now to enable the spring. First of all, make sure to disable the option, disable collision because right now there is no collision happening. If this box is checked, there won't be a collision. So enable the collision by unchecking the box. I I hit play, everything will keep functioning the same way. So now the question becomes, how can we enable the spring constraint? Well, right here you will have all the different settings related to the spring. You have the angular and the linear settings. The angular ones will control the rotation of the spring and the linear ones will control the translation of that spring. I'm going to enable all of them, and now if I hit play, notice what will happen. It will fall down because the stiffness and the dampening are super low. So here's what I will do. I need to increase all of these different values. Let's say 200 here. Same thing for the Y stiffness and same thing for the Z stiffness. Also make it 200 here, 200 on the Y axis for the linear and 200 also here. And for these values, let's make them, for example, 50, 50, 50 dampening. Let's make it two, two, two. I got to these values when I was experimenting with the scene. So play with your scene until you find the values that works for you. But these are the values that control the strength of the spring, the stiffness and the dampening. The stiffness, as the name states, controls how stiff that spring is, and the dampening is how fast that spring will go back to its original position. So stiffness is how hard that spring is to actually move, and the dampening, how fast it will bounce back to its original shape. If I hit play, now we have spring. These are the most important settings by far when it comes to the spring constraint, because you can control the stiffness and dampening on an angle base for the rotation and on a linear base for the translation. You will also have a couple of more settings on top. You will have the limits for the angular and the linear, which is a way to clamp how much rotation how much translation there would be, which will allow you to control or to clamp how much rotation you want to be or how much translation you want to be in your simulation. These are settings that are really similar to the generic constraint that we just explained. And lastly, you will have the disabled collision, which is also useful option, which to explain it, I'm going to jump to the sphere and make the mass, for example, 100 kilograms. Now if I hit plane, notice what will happen. The spring will fall down because it can't handle the 100 kilogram bowl. Right now, the option for disabled collision is enabled, which means there won't be collision. There won't be collision between 10. Building Destruction: Building distraction simulation. Hey, everyone, and welcome back. This is the third exercise, and probably it is also the most complex one so far. We're going to take everything we've learned so far and put it into practice by creating this building distraction simulation. You will learn a ton throughout this video, and hopefully it will deepen your understanding of the world of rigid body simulations and blender. So yeah. Let's get started. Hello and welcome back inside with a blender, and the first thing I want to start doing is to take a general overlook on how this blender filed works. The blender startup file for the building destruction. You will have three different collections. You will have the top level, which does have the model of the building, which is this one right here. You will also have the frames or actually, sorry, this is the glass, and you will also have the frames, the metallic frames. You might be wondering, why did I separate them in this fashion? Main reason is because we'll be running a different simulation for each group of objects, which means that for the buildings, we will run a simulation just for them, same thing for the metallic frames, and same thing for the glass. And that's why I separated them into different collections. The other ones, middle level and bottom level are just some variations of this level. So if I just disable the top level for a second and enable the middle level, these are the levels that will be in the middle of the building. They are the same exact thing as the top level. The only difference is that if you notice the top level does have this rim edge on the top. Meanwhile, the mid level don't have that. Other than that, everything else is the same. We separate the building, we have the glass, and we have the metallic frames. The collection that is slightly different, it is the bottom level because it will have this entrance right here, okay? With the glass and the frames of the windows separated. Each one of these objects, I remember using the mirror modifier to build it. So if I just head tap for a second to jump to the edit mode, as you can see, I only modeled half of the building, and the mirror modifier is taking care of reflecting that on the other axes. And that's how I built all the different buildings. Something else you might notice is that these buildings are not really optimized. We have a lot of edge loops going. Main reason for that is generally, the more vertices you have in your object, the more you will be able to fracture it into different pieces. That's why I chose to add a lot of subdivisions to buy buildings so that later when I'm doing the fracturing process, I will have more pieces, which basically will make the simulation slightly more realistic. Same thing for the bottom level. This is the frames. Also, the frames does use the mirror modifier, same thing for the glass. Later on, we will be applying all of these different modifiers because we cannot fracture the building with the modifiers on. Now let's talk a little bit about the materials. So each one of these objects does have different materials added to it. Let's start with the building model. These material are common in all the different levels, by the way. So for example, for the bottom level, you will have the white concrete, let me just jump really quick to the tv mode. The white concrete is the color that is on the outside, okay? The painting concrete this blue. Interior walls is the color inside the building. It is almost white. The only difference is that I added a hint of cien to it just to separate it a little bit. And the inside, we cannot see it right now. But imagine later when we will fracture the building, we will have different pieces. The interior faces or the inside of those different blocks will have this color. And that's, I think the color of the concrete, okay? This will be really visible later when we fracture the building into different pieces. The frame does have a very simple window frame that is a metallic material. It is really simple. For the glass, it is a very simple glass BSEF added to it. The materials are really simple and they are not the main topic of the course. That's why I chose to keep them simple and straight to the point. So now let's start working on actually creating a building and destroying it. But first, let's create our building. The concept is really simple. We will be duplicating the middle level on top of the bottom level, let's say five or six or seven times and on the top, we will put the top level. But before we do that, I would love to apply, first of all, the modifiers. Let's, for example, select all of these. Let's start with the bottom level. And if you go to modifiers, either you can apply object by object, but there is another way which is if you select all of these objects and then go to object, convert to mesh, this will apply all the different modifiers. Let's also enable the collection for the middle level and the top level, select all of these objects, object, convert, mesh. This is the easiest way to apply modifiers on multiple objects at once. Next, let's start duplicating all of these different objects to create the building. I'm going to start with the middle level. By default, it is perfectly overlapping the bottom level. And that's not what I want. I want to shift it a little bit up. When I was modeling all of these buildings, the height of each building is 4 meters. If I just select, for example, the middle level and hit N to open the side bar, as you can see, it is 4 meters on the Z axis. So if I select all of these objects and then hit JZ and shift it by 4 meters they will be perfectly on top of the bottom level, but there is something I want to mention. If I just hit enter to confirm this movement, now the building is perfectly sitting on the bottom level, and that later might cause some problems regarding our simulation. It is highly recommended that when you have multiple objects that are stacked on top of each other to leave a small gap, it won't be noticeable in the render. But it will help blender when it comes to running the simulation. That's why I'm going to control Z to cancel this movement that I just did. Head JZ to move it also on the Z axis, and instead of typing four to shift it by 4 meters, I'm going to type 4.01. I will be leaving a gap of zero 1 meter or actually 0.0 1 meter, which is 1 centimeter between the different levels. Type 4.01. And if I hit one to jump to the front view, as you can see, it is not the visible which makes me think that maybe because of the top level, the top level does have that ring. That's why it was hiding this gap between them. But yeah, this is the main concept. If you did everything right now if I select all the different objects inside the middle level and then hit Shift R, nothing will happen for whatever reason, so I will also need to do it manually. Hit Shift D to tuplicate it, to only move it on the Z axis 4.01 to shift it by 4.0 1 meter in relation to the previous position and then hit you can see, right now, we did everything all at once. We hit Shift D to duplicate, shifted it on the Z axis, and then confirmed. This will allow me now if I hit Shift R to repeat the last process, this will automatically redo the same steps that we did. All you need to do is to hit Shift R until you have the number of levels you want. I'm going to zoom out a little bit, let's say shift Rshift Rshift Rshift RShiftR we do the job. So now we have one, two, three, four, five, six, seven, eight, but we need to put the top level on top. So it is still sitting at the bottom of the building, so we need to shift it up. So the question now becomes by how much, which is one, two, three, four, five, six, seven, eight. So eight multiplied by 4.01. If I open the calculator and I do eight multiplied by 4.01, that's 32.08. But because we need to also leave a gap between between it and the level beneath it, it will be 32.09. Select all of these JZ, 32.09. Just by doing this, now we have this model of the building that we will destroy. Right here, I did a small mistake. The top level right now is sitting on one of the mid levels. To fix that, make sure to offset the top level by a value of 36.09. Later in the video, I will discover that mistake and fix it. But for you, you can fix it from. Now the last thing, I want to reorder my outliner because that's not the structure I want. I only prepare the structure for creating the building, but we're going to change it. We want the frames to be on their own collection, same for the glass, and same for the concrete buildings. This will be really simple. If I go to the search and type, for example, frame, I will have all of these. So just hit A to select all of the frames, hit M to create a new collection, hit N for a new collection, let's call it frames and hit Create. So now we have a collection for the frames. Next, let's type Glass. Blender will show me all the glass objects. So hit A to select or sorry. Let's hit A to select all of the glass here. M, new collection and type glass and hit Create. And last thing, let's look for level. I will have all of these objects. Hit A to select everything, M, new collection. Let's call it buildings and hit Create. And let's disable the research. And that's how I separated all of these different objects to their own different collections. And actually, I can delete these three collections at the bottom, the middle, and the top level. And if you want to go a step further, you can create a new collection and let's call it windows, move the frames collection inside windows, and move the glass collection inside windows. So this is the structure I'm going to use start as of now, one thing I just noticed is that apparently, there are two levels overlapping on top, and my theory is that the top level is actually overlapping another level. That's why I'm going to jump to the building, the top level. And as you can see, it is over one of the middle level. That's why I'm going to hit J Z to me on the Z axis, 4.01, and now it will be sitting perfectly on top, and it seems like I will need to do the same exact thing for the windows. So let's jump here, select the glass and the windows, J Z 4.01, and they should look perfect. Also, the other thing since earlier when we were using the search process, when we type frame and you type level, also there is this frame and glass of the bottom level. They are not in their corresponding collection, so let's take the glass and move it to the glass. Take the frame and take it to the frames. And now our structure is perfect and we're ready for starting to fracture the pieces. Since this video will be on the longer side, I would highly advise that whenever you see these chapter breaks that you save your file, save incrementally. Next, let's move on to fracturing the building. First, I'm going to disable the Windows collection because I don't need it for now. I only want to leave the concrete building, and for fracturing the building, we're going to use an add on called cell fracture. So the first step will be to enable the cell fracture add. To edit preferences, and you can go to get extension and look for cell fracture. You will have here an install button or update button depending on whether you installed it before or not. So just click on Install, and it will be added to your computer. It is that simple. Once you install it, go here and click on Save preferences, and you're good to go. Now we can fracture the building. What I will do is to select this entire structure called buildings by double clicking on the collection. Then go to Object. Quick effects. You will have here cell fracture. Click on this and let's start talking about the different settings that this add on will give us. Cell fracture add on will take a model and fracture it into different pieces. But there is an important question that we need to ask ourselves how to control how many pieces there will be? Well, the point source is just a way to tell the cell fracture, add on how many pieces we want. Own verts will use the number of vertices that form your object as a number for how many cuts. If your object, for example, has 200 vertices, then the cell fracture add on will try and divide it or break it into that number of different pieces. Child verts, in case you have a parent object and a child object, it will fracture the parent object based on how many vertices and the children object on particles. In case you do have a particle system, you can use this option, child particles in case you have a particle system on the children object and the annotation pencil in case you draw with the annotation pencil, you can basically specify where you want the cuts. Source limit is how many points or what is the limit. For example, let's say you do have 1,000 points. So the cell fracture add on will try to break the object into 1,000 different pieces. You can specify, like, Hey, I only want, for example, 100. And the noise is just an option to randomize the fracturing process or randomize the point distribution, as you can see. In our situation, I'm going to choose own words. And as you remember, I mentioned intentionally made a lot of subdivisions in the building model to have a little bit more pieces, so that should make the simulation slightly more realistic. And for the source limit, let's just increase it to something like 500 and bring the noise up to one to make it uneven. Recursive shatter is just a fancy way to tell the cell fracture add on, for each piece, please also divide it even more. And that's what this recursion means. And most of the time when I use it, I end up with a result that looks slightly like just using the point source. So that's why we're not going to touch this. We're going to leave it the way it is. Next, let's talk about mesh data. This is important. First of all, smooth interior. When using the cell fracture add on and we're talking about interior, we mean the interior faces that we can't see right now. So smooth interior, we set the inside of those different pieces to smooth shading. For the material, we also can specify the materials of the inside. And if you remember, if I just leave this for a second and jump to, for example, one of the materials, you will have here the inside. So we want to assign the inside to the inside of these different pieces that we will have later, okay? We go back to selecting all the different objects, object quick effects, cell fracture, and by default, this anon will forget the different values. Onwards, 500 and we're good to go. For the materials, we can assign which material we want to be the inside material. It starts from zero. So this is zero, one, two, three. So from here, bring this to three. So Blender will use the inside material for the inside faces. Sharp edges will set the edges to sharp, not smooth. Interior V group or interior vertex group will create a vertex group for the interfaces in case later you want to change the material something like that. This can be really useful. So I would highly recommend that you always enable this option. Next, we will keep all of these different settings the way they are. And for collection, we want all the pieces to be inside a certain collection, so we don't overcrowd our outliner. That's why I'm going to create a collection called building and rescore pieces. Or let's just call it pieces directly. And once you have your settings dialed in, just hit Okay, and Blender will start fracturing the building. This will take a little bit of time depending on how many pieces you will have in your building, but it some time, and I will see you in the next step. Okay, Blender just finished the fracturing process, and I will have this new collection called pieces. And if I just collapse it, as you can see, it does have over 5,000 pieces, which makes sense because our buildings does have a lot of vertices and a lot of subdivisions. Anyway, I'm going to take the pieces and bring it outside the buildings collection. For this building collection, I'm going to create new collection, let's call it, for example, archive to store the objects that we don't need anymore, and I'm going to take the buildings and bring it inside the archive and disable this collection. So now, this is our new building. And if I zoom in a little bit, as you can see, the building is fractured into a lot of different pieces, and the inside is now the dark color, and that's what I meant by the inside of those pieces. Control Z to cancel. And yeah, this is it for how to fracture the pieces. Next thing, we will make this building four. How can we do that by adding a rigid body system to all of these different pieces? Double click on the pieces selection to select every piece, go to object, rigid body, add active. And this will add a rigid body to all the different pieces, as you can see. If I jump to the physics tab, every piece right now will have a rigid body system added to it. And now if I hit play, everything should start falling. It is starting to fall slowly, but because the simulation is really heavy on the computer, that's why from the beginning, I need to add a surface or a floor for everything to interact with, okay? Let's go Shift A, mesh plane. And for the size, let's make it, for example, 100 meters or let's say 150 meters. And instead of leaving it as just a simple plane, I'm also going to hit tab to jump to the edit mode, and let's extrude it a little bit down. This should technically make the simulation slightly more stable because the plane by default is infinitely thin, and that can cause some issues. Heat tab to exit the edit mode, and let's make sure that the origin set origin is in the origin to geometry. So the origin will be in the center. Rigid body to this plane and change it to passive. And while I'm selecting it, I'm going to hit M to move it to a new collection. I'll create a new one and call it floor and hit Create. And now, if I hit play, the building should start falling on this plane. The building now directly falls, but we want to stay in shape in the beginning and then at the moment Notice, it will start falling. So how can we control when the building will start falling? We need to add a collider object. I'll explain what I mean. I'm going to go back to frame number one, and let's select all the pieces by double clicking on the collection and just select randomly one of those different pieces. Let's next jump to the physics Sab dynamics. Deactivation. Right here, you will have a check box called deactivation, which basically means that in the beginning of the simulation, the simulation will be deactivated, and it will only start unless you disable this option and check this option or in case there is an object that collide with the building. So we need to check this box for all the different pieces. That should be really simple. Make sure to hit Alt and then click on deactivation. Next also while you are hitting Alt, click on Start deactivated. By hitting Alt and checking something or changing a value, you will be applying the setting to all the different objects all at once. Now if I select randomly another piece, as you can see, deactivation checked, start deactivated check. And if I hit Play, nothing should happen right now. And as you can see, the simulation is already running faster because nothing is happening. So the question now becomes, how can we start the simulation? We need to add an object that will collide with this building to start the simulation process. So to do that, I'm going to go Shift A, mesh, and let's add, for example, an ICosphere or a sphere. It doesn't matter. For the sign, let's make it 5 meters. So it is here in the center, JZ and 5 meters to move it 5 meters up, so it will be perfectly sitting on the ground. Let's hit seven to jump to the top view. Let's just jump to the irregular shading so we can see everything in a better way. And what I'm going to do is to animate this sphere to collide with this building to start the destruction process. Okay? So on frame number one, let's say it will be here. Hit K to insert a keyframe for the location, location. Move on. Let's say, for example, 20 frames and J, and let's move it inside the building, as you can see right here, seven for the top view, K, insert another keyframe for the location. By default right now, nothing will happen because this kosphere doesn't have a rigid body system added to it. So first of all, let's select it M, new collection. Let's call it collider. Create. For this icosphere, add a rigid body to it. It should be an active object. And since we want to animate it, use it keyframes, make sure to check animate it. And for the shape, change it to sphere. Now if I just go here and let's see what will happen when the simulation starts. Let's play. The building will start falling. But for now, that's not what I want because actually, that's what I want, but there is a slight problem that we need to fix. Basically, this cho sphere, after it collides with the building, it will stay there. So all the different pieces will fall in this direction and this direction. We don't want that. We want the sphere to disappear at a certain moment. That's why while I'm selecting this sphere, let's say I want to start scaling down to zero once it collides with the building, which means I'm going to hit seven to jump again to the top view. And let's say, starting from the moment it starts colliding with this building around here, going to hit K to insert a keyframe for the scale, and once it fully collides with the building somewhere, let's say, around frame 25 S zero, I'm going to scale it by zero and K to insert a keyframe for the scale. So now the icosphere will collide with the building, and once it collides, it will shrink down because we scale it down to zero. This should look something like the following. Oh wait, nothing is happening. Yeah, this is how our building will fall just like the following. Which I think I like it. It looks good. Okay, everyone, this is it for how you can add a rigid body system to all of your different pieces, how you start your simulation by being deactivated and how to initiate the destruction process using a collider object. In the next part, we're going to make the simulation slightly cooler by adding some constraints to it and basically to add more variation to how this building is falling. As usual, make sure to save your file. In this part of the video, we're going to add more variation to how this building is falling. This will be really simple. We're going to add a couple of constraints to all of the different pieces, and this should technically give us a slightly more pleasing result. Be generally when a building is falling, there would be a lot of chunks that stay connected because of the metal bars and all of that. The goal of this part is to create something similar to that. To do that, let's select all the different pieces by double clicking on the pieces collection. Next, go to object, rigid body and choos the option for connect. So it is important to mention that since we have over 5,000 objects, it is important to wait because these sort of processes tend to take a lot of time in blender. So don't worry in case your computer freezes for a second while it is doing all the work. Okay, blender just finish adding all the constraints, and please don't click on anything because we still need this menu in a second. So if I go to the front view by hitting one from the number pad, you can see, and let me hide all the overlays. Okay, I'll need those. All of these constraints are weirdly distributed, as you can see, for example, from the back. The main reason for that is that the connection pattern is selected to active. So basically, Blender created all the constraints based on the active selected object, and that's why they are weirdly distributed like the following. So we need to change this option, the connection pattern from selected to active to chain by distance. So change that. Blender will need to recalculate everything, so wait for now Blender just finished recalculating, adding the constraints. And as you can see, right now, they are randomly distributed in an even way between all the different objects. One important thing is that all of them right now are here and they made the outliner Ms. That's why I just select one of those constraints, hit Shift G to select similar, and from here, we can select all the objects that does have the same type, which means all the different constraints, hit M to move them to a new collection, new collection, and let's call it constraints and hit Create. And let me collapse it. So all of my constraints will be living in this collection right now. I hit play, let's do this. Let's see how it will look. Et me just hide the overlays to see the result in a better way. As you can see right now, all the different pieces are kind of connected, and that's because of the constraints right here. Already, you can see how the foling process right now is slightly more realistic because some pieces are connected to each other. But I think the connection between them is too strong. That's why I want to lower it a little bit, and that's what you can do let me enable the overlays. Select one of those constraints. Let's select all the constraints by double clicking on the collection. And if you go to the physics stab from here, you will have an option for breakable. This means that at a certain point, we can break the constraint that is connecting the different objects. We want to enable this option for all the different constraints. So while you're holding Alt, click on this and this will make all the constraints breakable. When will they be breakable? You have this threshold number. I tried looking for what is the unit of this. It seems like it is an arbitrary number that define when the constraint will break. In my experience, I'm going to select all the different constraints, select one of them to be the active one, and let's jump to the physics stab. Going to lower it to something like five, click on this type five, and before you hit Enter, make sure to hit Alt and hit Enter, and this will apply the value of five to all the different constraints. So now, once we reach this threshold value, the constraint will break. If you want to even add more variations to it, let me go back to frame number one and enable the X ray mode. Hit one, I'm going to disable the pieces collection, so I will only be able to see the constraints. Let's switch to the circle select mode, and I'm going to select a bunch of them randomly while holding Shift. Let's say something like so. Let's go back to the usual select box and select one of these to be the active one. For these ones, I'm going to lower the threshold to three, while you're holding Alt, click on Enter. All of these constraints right here will have a value of three meanwhile, other ones will have a value of five, which will add more variations to our simulation. Let's enable the pieces collection again, disable the X ray mode, and let's see how this will look like hit play again to catch the simulation. Let's stop it here, disable all the overlays, go back to frame number one, hit play. Mania, I'm digging this result. Okay, so this is it for adding the constraints to add more variations to how the building is falling, and now we can move on to the next step, which is baking the simulation so we don't have to simulate it every single time. But as usual, before you do that, make sure to save your file. Baking is simply converting the simulation into keyframes. Why would you want to do that? First of all, because every time we change something, blender needs to recalculate everything which is time consuming. The other thing is that now we need to create the simulation for the rest of the objects. Trust me when I say, if you try to simulate everything all at once, Blender will crash. No doubt. That's why we're working step by step, and that's why we need to make the simulation. Of course, some of you might be worried about losing all of these informations like the rigid body added to the pieces or the constraints. But I want to remind you that we're saving incrementally, so we can always go back to one of the previous blender file and restore our previous work. This is my usual workflow when it comes to baking up stuff. Instead of saving backups in the project, for example, duplicating the constraints and putting it in the archive. Same thing for the pieces. I like to have different blender files, so the blend file I'm working on is always light and optimized. So how can we bake our simulation into keyframe? As usual, this is really simple. Let's select the entire pieces collection by double clicking on it. You can't see the selection because I need to enable the overlays. We selected everything. Next, go to object, rigid body, and from here, we should have the optict for bake to key frames. And I think this option is not highlighted because one of the objects must be in active selection mode. So while you're holding shift, select randomly one of the pieces. Then if you go to object, rigid body, you will have the option for bake to key frames. Click on it. You will have the start frame and end frame, which is basically the range of baking. I'm going to leave it the way it is and just hit Okay, and now as usual, let's wait for Blender to bake the simulation. This will take a little bit of time, so wait for it, and we'll move on to the next step. Okay, so the simulation finished baking, and as you can see right now, I have a lot of keyframes, and this was the simulation we had earlier using rigid body that. Right now it is all baked into keyframes, which is better because we won't lose our progress anymore. And now we're ready to move on to the next step, which is to add a particle system to add more details to our simulation. If I just disable the overlays for a second, this simulation still needs a lot of details. We need small particles that should be flying everywhere, and those will be the small debris when the building is collapsing. We don't have that. Right now, we only have the big chunk we will create those small particles using a particle system. But before actually we do that, since we don't need our constraints anymore, you can double click on this collection and and then delete it. Blender will crash. Okay, that was an unfortunate turn of events. Blender crashed, so I had to rebake the entire simulation into keyframes. And this time, I made sure that I saved the file before deleting the constraints because for whatever reason, that might cause bleder to crash. And as I said, since we don't need this constraint collection anymore, I'm going to select it and delete high this way, we will have a slightly lighter blender file. Make sure to save your file as usual, and let's move on to the next step where we will be adding the particle system. Right now, we're going to add a particle system to add some extra debris when the building is falling. The particle system will be emitted from the faces of the building. But since the building right now is fractured into different pieces, adding the particle system will be a mess. That's why we need to turn all of these pieces into one object. Some of you might think that I'm going to select all the pieces and hit Control G to join them, but that's a bad idea. Instead, and it's actually the best way, we can use geometry nodes for that. To do that, I'm just going to disable the pieces collection and then go Shift A. And actually, since we don't need this collider, also, I can disable this collection. Next, go Shift A, mesh, and let's add a plane. We will have this plane in the center of the scene. We don't care about scaling it, but what I need to do is to change this editor to geometry node editor, new. Let's call this building, enable the magnets, so the nodes will stick to the grid nicely and hit to hide the sidebar. I'm going to delete the group input because I don't need this plane. I'm going to create my own geometry, which is the pieces collection, so just hit delete, take the pieces collection and bring it here and connect it to the geometry. And now you will have your building. The really nice thing about this setup is that we can always move this plane, and since it does contain the geometry note tree that contained the piece good to go. The only thing that you need to keep in mind that all of these right now are instances, which means they are not actual geometry. So now when we will add the particle system, we will not be able to emit particles from each piece. That's why you need to add another node called realize instances. And you can think of realized instances as just a way to tell blender that, hey, blender, the instances turn them into actual geometry. So now when we will add the particle system, we'll be able to emit the debris or the fractured pieces or the particle system from each piece. And yeah, this is the setup we will use to merge all the different pieces into one object. And you can actually call this, for example, building Geo node or actually let's change it to pieces because I think that makes more sense. And now we can create our particle system. So jump to the particle system tab from here, create a new particle system, and let's call it extra debris. Double click also on this one, extra debris. Will be an emitter object. What will it emit? That's really simple. You can disable the pieces collection for a second, and let me enable the pieces collection. Let's select randomly some of those pieces, pieces from different areas while I'm hitting Shift, of course. Then let's hit Shift D to duplicate those pieces, right most button to cancel any movement, M to move them to a new collection, New collection, and let's call it particle system debris and hit Create. And let's also disable the pieces collection again. Select the particle system debris by double clicking on the collection and hitting G to resit the position. So everything right now will be in the center and also disable it. Let's go back to our building geodes particle system. And yeah, now we can start building our particle system, and I think it makes more sense to change this editor to the timeline. And yeah, if I hit play, the building will start falling. So we need to ask ourselves at what moment we want to start emitting the pieces. And I think somewhere around frame 20 or let's say frame 18, that's a suitable point because the moment the building starts falling, we want to start emitting the different particles or the debris. And to be able to see that, let me go to render and from here instead of render as halo, because we're not seeing anything, let's change it to collection. And for the collection, it is the porticle system debris. Also, let's hide the overlay. Let's go to the emission settings. For the number, let's say I want to emit 5,000 small pieces. Frame start. I want to start emitting those particles at frame 18. And for the end frame, let's say I'm going to emit all of those different small particles. For let's move forward. When does the building kind of stops collapsing? Say at around frame 40, so end at 40 for the lifetime, which means for how long you want those particles to be visible or to stay in the scene before they disappear, each particle should stay until the end of the simulation. So make sure to bring this number up to 250, and don't worry about the frame range because blender, at the end of the day will only render until frame 250, so we're good to go. Lifetime randomness that for the source, we want to emit them from the faces, and probably you're wondering why we can't see anything yet. The main reason for that if I jump to the modifiers tab, as you can see, the particle system is after the geometry nodes, and by default, the particle system doesn't count in the modifiers.