Siggraph 2017 Rewind - Eric Nicolas Smit: Fracturing in Cinema 4D

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  • Made with Release: 19
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Break a marble sculpture with Voronoi Fracture and Dynamics.

In this presentation from SIGGRAPH 2017, artist Eric Smit shows off the new features added to the Voronoi Fracture object in Cinema 4D R19. He walks through all of the major steps involved in creating an effects-quality shot of a marble bust breaking apart as it hits the ground.
He begins with a description of how he sculpted the head and how he then reduced it down to a reasonable polycount using the Polygon Reduction object and the Sculpt Baking system. He moves on to a general discussion of how to use the Voronoi Fracture object - creating good looking results with only a cube. He closes out by applying all the earlier techniques to his more complicated model including dynamics tools like Connectors.

00:00Introduction
00:28Shattering the Head of Zeus
02:14Generating Dynamics Proxies
05:08Baking Lightweight Versions of High Poly Sculptures
07:48Baking a Dragon
08:56Overview of Voronoi Fracture
11:26Voronoi Source Modes
18:38Using Connectors to Keep Fragments Together Longer
21:48Making More Realistic Cuts with Detailing
26:07Fracturing the Head
26:58Adding Dynamics & Connectors
29:25Finished Head Fracture
30:21Texturing the Inner Faces with Selections
31:40Detailing
32:51Geometry Gluing
34:27Teaser Film

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Transcript

Hi, everyone. So I'm Eric Nicolas Smit, I'm a longtime Cinema 4D user. I'm a visual designer and 2D artist and I have been using Cinema 4D for now, almost 15 years, it's my favorite creative tool. And today what I wanted to do with you is to break something. So we will grab an object, let it fall on the floor, and see how we can create the most realistic and convincing shattering effect. So we will create something similar to this. So this is the effect we will create together. To create this effect, I will be using the Fracturing Tool in Cinema 4D, as well as Dynamic Simulation. So let's start with the original object. Here we have a sculpture, it's Zeus. I sculpted it in Cinema 4D. It's a very high-density object. It goes, let me check, almost 1 million polygon. I'll switch off here the texture so you can really see how it looks here. So we have a fairly high amount of details. I'll bring back the texture. Here. And its texture is made of one very large color map. This color map, I created it inside Cinema 4D. It's actually baked procedural noise as well as ambient occlusion to create a bit of dirt, like around the eyes and here, in the air structure. I have also, in this material, a sub-surface scattering effect. This is to create translucency. And then a bit of reflectance and an environment map to make it a bit glossy. And finally, bumps. I'll just hit render to let you see how it looks rendered. So here is how it looks. Now we could use this model directly in a dynamic simulation, we could break it and then let it fall but since it's so heavy, we need first to optimize it. To optimize it, we have many tools in Cinema 4D. Before optimizing it, I'll just show you something here. So here we have three different version of my statue. And we will all agree that they are totally similar, they look the same. I mean I doubt that anyone here would notice a difference. They are, however, totally different. In the center we have my original sculpt, but on the sides, we have highly optimized version. In terms of polygon count, this one here on the right side has only 2% of this model. And this one here on the left side, it's, I think, 5%. If I switch here to the Display option and I switch to a Line Shading here, you can see their respective structure. So in the center, we have my high-density sculpt, and on the sides, we have two optimized version. I'll switch back here to a normal display. And what we have here, in fact, is here, I have my original model and on this side, I have a baked version. And this baked version is actually a low polygon structure plus a normal map, and I created this map in Cinema 4D. I'll just show you how it looks, my normal map. So it's basically the same model, but with the high details baked into a normal map. I'll just open it here. And here you have it. It's a RGB image, where each color indicates a direction, so it's a 3D surface deformation. And as you can see, when I switch here back to a normal shading, these two models are identical. But one is extremely light. I'll just check here. Its structure here, we have only 15,000 polygons, while this one was 1 million. So baking is a great way to reduce the density of your object and get something extremely light that will give you a real-time preview of the fracturing of the dynamic simulation. This would be way too heavy to run any kind of dynamic simulation, and this one is extremely light. So to create this baked version is very easy. You just grab your original sculpted object, and in the sculpt layout, you have here Bake Sculpt Object. So I just click on it. And then in the option, you can say that you want the upper level details to be baked into a lower target object, a low-res mesh. And then you just have to click Bake and it's done. I'll just run a preview here. And this is my normal map, it's in Tangent mode, but I could also use Object mode. And then that's what I did for the baked version on the right. Here's the preview. And this is the map that you saw earlier. So that's how I can bake my sculpted object. It's a very simple and fast process, it takes 20 seconds approximately, and it can save you a lot of rendering time and pre-calculation. Now the other object that I have on the other side here that looks also really good, it was done using the Polygon Reduction Tool. This is a brand new tool in Cinema 4D, you can find it here in the Modeling. I'll just load one here. And it's a polygon reducer. Quite aggressive, because I could, here, go down to only 5% of the total polygon count of this one. But it keeps the shape of the object intact, almost. If we check here, it's very similar. Now if I turn off the texture, then you will start to see that we have a little bit of difference. Here, you can see that it's not as smooth as on my original sculpt. But when it's textured, then there's no problem. We don't notice this. Here, we can barely notice it. And if you're working for an animation with the motion blur with the movement, you will not notice the difference. So this was just two different ways to optimize your object. And since this one is the lighter, I'll show again the structure, we'll just keep this one to run the simulation, the shattering. So I'll just remove the other one, we don't need them anymore. This one is gone, and the original as well. And I'll switch back to my standard layout and bring it back to the center. Now I have here another example of baking that was quite striking. I worked one or two years ago for the Vulcania Amusement Park and they needed a dragon, a very light dragon, to be animated so I created one. This was my original sculpt. And then I used the Cinema 4D's tool to create this one. And it's very light, a low polygon object. Here if you check the structure, it's extremely light. But we had exactly the same look, the same structure. They are almost totally identical. So whenever you work on an animation project, on a simulation project, don't hesitate to use Cinema 4D's Optimization Tool because they are really powerful. Now back to my project, and my project is fracturing, is breaking my head. So I'll go back here to my head. And now we could just go ahead and start breaking it and creating the effect. But I would like to first go to the settings that we need by using a very simple setup. I always like to keep things extremely simple when I try parameter so that I can see them in real time and I'm not distracted by shading, by illumination, and little details. So I'll just create here a new scene, and we'll work with just a plane here and a cube. And we'll start playing with the setting to get our shattering effect, our fragmentation. So this plane will be my floor, my collision floor. And we'll assume that this cube is a block of stone, a block of marble. It's just the same material as my statue. I'll just make it here a bit higher, like so, and a bit thinner. Okay, now I need to create my dynamic setup. Before that, I will break my cube into fragments. So the fragmentation, for the fragmentation, I will use here the Voronoi Fracture. And I'll just drop my cube in it. Let me just bring it back to zero here, like this. So here the Voronoi Fracture is Cinema 4D's tool that you can use to break an object into pieces. And it breaks it into blocks, these are cells. And they are all convex cells, it means that they're facing outwards. All of their polygons are facing the outside. And this is really useful for that dynamic simulation because convex shape create better dynamic simulation. So here we have this group of blocks and they are now in a uniform distribution. And for my effect, because I want here this block to fall on the floor and to break apart, I don't want to have a uniform cell distribution. So we have here in the Voronoi Fracture, different type of source. It's called the Point Generation Distribution. We could use here Uniform, and this is uniform. So we have random, but they're organized, distributed on the object exactly in the same way. We can increase here the density, but it's still uniform and that's not exactly what I want. What I want is to have more fragment on this side of the impact. So for this, I can switch to a different type of distribution. We have Normal, and normal, you get the points here in the center of your object. And you can adjust here the curve. Let me increase here the density so you can see it better. So here we have in the center, and as we go high, it goes back to uniform distribution. Then you have the Inverse Normal, and there you get fragments on the edge of the object. Here, again, it was a Deviation. And this type of distribution would be great if you had a very solid object and you would want only to damage its border. And then we have another distribution type, it's Exponential. And this is the one we will be using for our shattering effect. And exponential, it puts more fragments on one side of the object and you can control this with X, Y, and Z directions. So, for example, if I say plus here, Y, I get my fragments here on the bottom. I'll just hide the points so you can see it clearly. So here, I have my fragments right at the bottom where they will impact the floor. So I'll just create now a dynamic simulation setup so you can see how it looks. So for my plane, I will just use here a simulation tag, a Collider Body. And here for my fragments, I will use here a Rigid Body. Rigid body is for a solid object. You also have soft body, but here, since we're dealing with a rock stone, it's a rigid body. So now we have the dynamic setup and we can run it. I'll just increase here the amount of frames. And if I play it back, our cube is already shattered in pieces. Now the issue that I have here with this setup is that we have a lot of sliding. My little fragments slide on the floor as if it was ice or if it was a surface with water. And this is not the effect that I want to achieve. We're dealing with a concrete block, I mean a marble block, on a concrete floor, so there should be a little bit more resistance. Here it's just sliding way too much. And to change this, we need to adjust the friction parameter. And the friction parameter, it's in your Rigid Body Parameter. Here, you have Collision. Let me see. No, it's in Mass. No, it's here. It should be here. We have the friction parameter. And what the friction does, it increases the resistance between surfaces. So with a high friction, you will get more resistance and with a low friction, you will get a lot of sliding. So if I increase here the friction up to, say, 80%, my objects slide less. I can do the same here for my floor. So we get both surface with a very high friction. Then you can see the little fragments, they remain here, they're not moving away that fast. I'll just show you with zero friction on both geometries. So here we have a very high sliding effect. Very strong, sorry. So for my project I'll just use, let's say, 40%, like so. And that should be good enough. Now another thing that bothers me is that my little fragments, they move for too long. If I hit render here, you see that they just continue their course here. They're just moving for just too long, and I would like to reduce this. What I want is a block that falls on the floor, and then you get fragmentation, bam, and it's over. I don't want these little fragment to just dance around. So I can change this by here working with the damping. And here in the fragmentation in my rigid body dynamic, I can use here Damping. And damping, it's the reduction of the kinetic energy. So my fragments will lose their speed faster as if they were asleep or as if they were blocked by other objects. So if you have a very high linear and angular damping, like so, then it's almost like slow motion. Here you have a big difference. I mean, my objects reach aesthetic position very fast. While if it's a low linear and angular damping, then the fragments just travel for much longer. And for my effect, since we're dealing with a large block of marble on a floor, I want to have a relatively strong damping, so I would say 50 here. Now we have two value, Linear and Angular. Linear, their trajectory is like this, and the angular is if they rotate. So we say 50, 50. And then we have something like this. Now there's one thing that bothers me as well, is that when my cube hits the floor, all the fragments are activated directly. We don't have a progressive shattering, as if the blocks were not connected together, as if we were dealing with particles, ;ike one group of particles falling on the floor, and then breaking apart. I want my shape to keep its structure for a bit longer. So for this, we have here a brand new tool, it's the Connectors. So now we can connect the pieces together. And what connectors does, sorry, it restricts the movement of dynamic objects. And in this situation, what I would like to do is to fix them all so that they stay together unless they are affected by a very strong collision. So I'll create here a Fixed connector, like so. And now we have one Global Fixed connector. I'll just play it back. And we don't see yet the effects. I'll need to increase here the force and torque. And if it's up to 80, 80,000, then you can see the effect. I'll just switch my camera, move it here. And I'll change maybe here the structure so you can see better using... I'll just change here. Just so you can see what the connector does. And let's try again. So now, you see we have a progressive fracturing. I'll just increase here so you can keep going. So we have a large block. And at the point of impact, my little fragments start to move away, but the rest of the structure, the large block, they remain connected. And if I play with my fixed connector settings, I can just find the right setup for my project. Here, for example, that would be okay. Now here in the Breaking Force and Breaking Torque, we have here two value, Force and Torque. Force controls the push-pull force. And then torque, it's the rotational force. So if I use here 50, then we have something that's probably good for the effect, like so. I'll maybe reduce here the damping a little bit. Okay. That's good. So now we have a dynamic simulation that looks more or less like what I want to achieve, but there's still one issue, is that if I zoom in and you see the cells here, you see we only have sharp and linear cuts, and this is absolutely not realistic. In here, it seems that the block was cut with a laser and that it was not fragmented by a shark. And also here, the inner faces of my cells are also way too flat, so now we have a new tool in Cinema 4D to change this and it's quite impressive. Let's just bring my block here to its original position. And it's the, here... Let me see. Detailing. And what detailing does is that it introduce noise and irregularity in the structure of the cells. So I'll just activate it here. I click Noise Surface. And you can see here, we went from a straight line to something irregular. I'll just turn it off and on. Let me add a bit of offset so you can see clearly the structure. Okay. So we went here from these sharp edges to something irregular. And if I click play here, you can see that my fragments, their inner face are irregular. I'll switch it on and off. On and off. So we have now a more realistic effect, something that looks more like fragmented rock, and not laser cut rock. And in here, the detailing, you have many, many options and tools to adjust these rough edges and surfaces. You have all the Noise type, these are the classical Cinema 4D noises. For example, here we could try this and we get a totally different structure. And then we can control the Noise Strength, the Seed, the Global Scale, and all the parameter, the classical parameter. The Clipping is also nice because then you can just get something a bit more rough and contrasted. And then we have also here Relax Inside Edges. And here, we can smooth out the edges here of the inner blocks, and this is also great to create a more realistic shattering effect. Okay, so now I have quite a good setup and I can mimic it to my statue but before doing so, I'll just show you a quick video of all the settings that I changed. So here we have the friction. So low, green and blue, high. You see the very strong sliding. Here we have the damping, the blue, high so the movement is absorbed faster. And then here, we have the connector. The green has no connectors so all the fragments explode directly. And then finally here we have the detailing. So here, green is sharp edges and here, blue we have rough edges. And here it's a zoom. So we have a really natural chunks, blocks of rocks. So now I can apply all these effects to my statue, so I'll get back to it. Here. So here my statue. And we will now fragment it just with the same settings that I used and just let it fall on the floor. So I'll quickly create the setup. We'll grab here my Voronoi Fracture, goes in it, and then it's fragmented. And then, I'll go back here to the source and switch to Exponential and just increase the point amount a little bit. And we'll have here a vertical Y-axis exponential curve, like so. So you see we have more fragments in the bottom, like so. And then I can place my floor here. I'll just raise my statue head off here. And I'll increase the size of my floor, and I'll create the dynamic setup. So, again, here on my fragments, I place a Simulation tag, a rigid body dynamic, and on my floor, a Collision tag. Again, Simulation tag here, Collider Body. And now in the Rigid Body settings, I'll just do exactly what we did, I'll do it quickly. So here in Collision, I'll increase the Friction. Then here in the Force, I add Damping, so we won't have that much kinetic energy, it will be reduced and we'll have a controlled fragmentation. Also here, the Angular Damping. And then here, I add my Connectors. Sorry. Like so. It's my Fixed Connector. So the large block not directly affected by the collision will remain together and it lets me rotate it a little bit. And now, we have the effect that I wanted. And then here, I can change the random seed of my point distribution. For example, like so, if I want a different effect. Like so. And if I manipulate here the Connector Force and Torque, then we can have...the shattering can be more dramatic. Maybe something like 30? Okay, that looks fun. But instead of playing here with the settings for very long, I'll just open up one configuration that I created and that I liked. It's this one. I'll just play it back for you. So in this simulation, what I liked is that we have here the first impact, so we have here a very strong shattering. And then when the head goes to the side, we still have little flying fragments, like so. So, yeah, this is the sequence that I created. I'll just play it back here the render so you can see how it looks rendered with the subsurface scattering and the ambient occlusion. Now you might wonder how, here the inner faces, I managed to texture them. So we have here in the Voronoi Fracture here... Let me switch here, right up. We have here a Selection tab. And in the selection tab, we can create selection tags here for every aspect of the fracturing. So we can add tags for the inner face, for the outside face, but also for the edges if you want to create specific effects. And for the inside vertices, the edge vertices, and so on. And you can also create vertex maps. So what I did is that I created... I have one selection for the inside face and it's here, the little triangle tag. And then I loaded here a new material, it was mine here, and it uses just here a rock color map. And then the other settings are exactly the same as my statue. So this one doesn't use, this simulation doesn't use detailing, so we still have sharp edges. And I'll just load here one with detailing. And we see here we have very rough inner faces, and also the edges. Let me activate here the scream. Where is it again? The Enhanced OpenGL. And I'll have...and Display, Option, Texture. So we can see here we have very rough edges, totally irregular. But it requires a bit of calculation, this detailing, to get this more realistic effect. I'll just play it back. So that's the type of render I wanted to achieve. I'll just load up here the render. So that's my final render with the detailing. So, yeah, that was my little presentation of the Fracturing tool. And we have yet...there's also one other tool here, it's Geometry Gluing. I'll show you quickly what it does before wrapping up. Here we have the... I'll just load here my Voronoi Fracture. And then you see here we have the group of cells. I'll just increase the density here. And now here is geometry gluing. here, we can glue a few cells together. This is nice if you want to have just fracturing on one part of the object. So we can enable geometry gluing. And then we have a Falloff. We can add a falloff, sorry, here. And then with this falloff you can...let's switch it here to a sphere. So you can glue cells together. So here, for example, I'll just make it larger. We can here glue groups of cells. So this is another new feature in Cinema 4D Release 19. It's here, the Voronoi Fracturing Gluing with Falloff of different shapes. So this is another tool that you can use to create a nice effect. Okay, before leaving you, I'll just run a little teaser to invite you to visit my website and discover my work. It's just a little sequence where we travel in a world, the kind of world that I like to create. ♪ [Music] ♪ So thank you. It was nice talking to you. I'm Eric Smit.
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