Cloth Simulation, Part 08: Bursting Through a Banner with the Tear Option

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Instructor Donovan Keith

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Use the cloth tear option to create a countdown animation.

One of the coolest features of Cinema 4D’s cloth simulator is the “Tear” option. It allows you to simulate cloth ripping apart when its placed under too much stress. We’ll be taking advantage of this feature to create a countdown animation.



One of the coolest features of Cinema 4D's cloth simulator is the tear option. It allows you to simulate ripping cloth apart when it's placed under too much stress. We'll be taking advantage of this feature to create this countdown animation that you see here. Three, two, one, Cinema 4D and it's being torn for some reason, I don't know why. Okay. Let's go ahead and dissect the end project file just to see a little about what's going on before we get too invested in this. So let's take a look at this from the side view. When I come in, I see that I've got four planes lined up, I've got a camera pushing forward and it seems like the camera is somehow with its view [thruster] somehow doing that, well not exactly. What's happening is there is an object that's been animated, it was a sphere. This is what I was hoping was gonna be doing the collision the first time, but it didn't work as well as I hoped. So then I threw in a cube and the cube is what's actually colliding with the surface. So you'll see that we've got a cube, it's rotating slowly and it's jiggling just a little bit side to side and that's happening so that each of these tears are not absolutely identical. The other thing that I want to point out is that our planes which have been used are just square planes, have their corner points pinned in place. So let's go ahead and create an animation not unlike this. So go ahead and create a new scene and let's add a plane object to our scene, I'm gonna set the orientation to minus Z and I'm gonna turn on Gouraud shading lines just so I can see the general number of subdivisions. The more subdivisions you have, the cleaner your tears are going to be, but you'll also have much slower simulations. So you kinda have to pick and choose your battles on this one, I'm gonna go with 30 by 30 segments to start and I'm gonna call this banner. Now typically you wanna make your plane objects the same width and height as your final output resolution just because then they've got the same aspect ratio and it's a bit easier. Or you wanna make them at least the same width and height as your texture that you're gonna be applying to them if you want non-view sized banners. But we're not putting a texture on this so let's just do square, okay. So I've got my banner now, I'm going to, as I've done in many of these other videos, I'm gonna duplicate it, I'm gonna call it banner backup. And I just do this so that I can always come back to this if I want, turn it off and hide it. Now I've got my banner, I'm gonna make it editable 'cause we need polygon objects for our cloth tag, . And I'm also now going to use the linear clone tool, so I'm gonna type in linear and there's a linear clone tool that will show up here, and I'm gonna turn on snapping and I'm gonna turn on, let's say, grid snap or work-plane snap along with grid point snap. So, you can now see that we've got a little bit of snapping happening right here, I'm gonna click in the first one and then I'm gonna start dragging this way. And it's gonna go three, two, one, Cinema 4D. So we're gonna need five of these. If I click and hold shift, I can adjust the number so the first is one, two, three, four, five I think we're doing pretty good. Actually, I think I want one fewer than this, so I'm gonna just slip this over to this larger grid point and shift down until we have the first is three, then two, then one, then our final plane. Okay, so we've got a clone of four of them and they're all lined up like this, guess it got lined up a little bit off to the side that's fine, I can just take my banner here and. . .or my cloner rather, and I'm going to set the x position to zero, there we go. Next up, let's go ahead and take our banner here and delete it and take our first cloner, and I'm gonna call this banners and then I'm gonna make it editable, so we get real live objects for each of these. And I'm realizing now that if I was really smart I would have done this before, but I'm not, so what I wanna do is select each of these corner points on these guys. Actually, we are smart enough so let's hit undo and select our first banner and let's just select each of these corner points because these are the points that we're gonna want to pin later on. So now selecting my banners, I'm gonna make it editable, I now have a group that's got a bunch of these objects in it. I'm going to select all of my banners and it looks like I lost my point selection, darn it, okay. So another way around this is to have all of these selected and then with my rectangle selection tool, turn off only select visible elements and I'm gonna select each of these corners, holding down shift. And it's just going to be selecting all the way through these objects and getting me these corners. So having each of those now, what we can do is add a cloth tag, so I'm gonna right click, choose simulation tags, cloth. We have a bunch of cloth tags. On the dresser tab, I'm going to choose set, next to fix points, and we now see that all of those points are fixed so when e press play they all start hanging out right there. They got a little bit of bounce going on so that means that we need to come in here and adjust our tag settings. So I'm gonna increase my number of iterations here to something like 20 so that we get a stiffer cloth. I'm gonna get rid of this whole flexion concept. And now that we've got that roughly set up, we've got some cloth maybe we can adjust the mass, but for now this is all right. What I wanna do now is add a camera to my scene and start animating it through. So let's add a camera to the scene, I'm gonna zero out its position, scale and rotation which I'm gonna use the reset PSR commands. I'm hitting shift C, typing in reset PSR, and that's gonna zero out my position, scale androtation and also give me this. And I'm also gonna go into my camera and in the object tab, I'm gonna change the focal length to 50 or normal lens, here. It's just a little bit more focused. And I'm now gonna move it back just a ways. And what I'm trying to do is ensure that I'm never quite seeing the edges of any of these guys, maybe I'll go even for a slightly tighter lens like a portrait lens and that'll do. Okay, so we've got this, we've got our camera looking through it, everything is going all right. I'm now gonna take my camera and animate its position moving forward. So I don't know that I have enough frames here right now, so I'm gonna go from 90 to, let's say, 150 and I'm gonna animate my camera along position .z. So p.z, I'm gonna hit record there, go to frame 150 and we're gonna snap through this guy as well and press record, okay. So let's look through this camera and play through this animation. We're gonna go through one, two, three, four, five, it's happening really quickly. What I wanna do is ensure that the interpolation on that key here is linear. So I've gone into my timeline, let's set them all to linear so when I play it back, it should be a more constant speed at which we're breaking through these various planes, that's looking all right. Now I just wanna give myself a texture or something to play with on these, so let's create a new material, and I'm gonna add a simple checkerboard surface in the color channel and I'm gonna double up or triple up the number of divisions maybe even five by five. And in the color channel I'm just gonna select maybe something like red and bring my mix strength down to 50, so we've got a color here and I'm gonna turn off reflectance so we don't have any specular. Now I'm gonna drag that onto my banners just so we can see a little bit more easily what's happening in this animation. Okay, great. We've now got our camera animation and that's gonna dictate what happens with our tear, so I now wanna add a cube to my scene and this cube is going to be sort of the first thing that breaks through. I'm gonna rotate it 45 degrees so, or maybe it's 30 degrees something like that, negative 45 should do it, so that it's lined up; the edge is lined up with this first piece of cloth. And I also wanna move it back on the Z axis here so I'm gonna go into world coordinates just drag it back a bit. And now that I've got this, my cube, I wanna maybe in my side view add a slight fillet to it, so I'm tapping the O key just to view that object. And I'm gonna turn on fillet so that adds a little bit of rounding here and I want enough rounding that I don't create too hard a tear, but I also wanna lower the number of divisions here so that I don't have to calculate too many polygons. Now this cube is well positioned, but it's really kinda cramping my style so I'm gonna right click on this and choose display tags, Cinema 4D display tags, and I'm gonna choose view or rather use shading mode line. This way we can still kinda see it in our side view, but it's not really messing up our view. And we can now play through our animation, see it's breaking through all right, and what I wanna do is turn this into a cloth collider. So right click on your cube, choose simulation tags, cloth collider. So now when you press play, you're gonna get something like this, it's pressing through, it's pressing through, it's pressing through but what's happening is our cloth, all of it is colliding with each other and it's getting super distorted, so that is not exactly what I want. So I'm gonna come back, I'm gonna select my cube here and, rather I'm not gonna select the cube, I'm gonna select each of these banners and I wanna turn on the tearing option. So selecting each of these, I'm gonna turn on use tear and then let's just press play on the side here and see what's happening. So it's pushing through and it starts to tear but then we get these weird polygon reactions and that's because the tear option doesn't work unless your objects are inside of a cloth surface object. So if I go to simulate cloth and I'm gonna hold down my option or my alt key as I do this, and choose cloth surface, I believe our first one of these should now actually tear, yeah. So that worked, so let's just follow that procedure for the rest of these; select your banner, simulate cloth, cloth surface, simulate cloth, again holding down alt or option, cloth surface and do the same thing for this last guy here. Again if we had been really smart, we would have done that before we even began but sometimes, you know. So we've got this tear, keep watching we get another tear but all of these tears are happening in roughly the same position which is not really that interesting to look at. So what I wanna do is get our cube to start varying its movements in an interesting way. So I'm gonna go to my coordinates tab, on frame zero I'm gonna press record and now on my cube, I'm going to add a vibrate expression, and I'm gonna enable position, I'm gonna have it maybe move 20 units, 20 units, 20 units and on rotation I'm just gonna let it rotate maybe 15 or 20 degrees on all of these. And let's just see what that looks like, yeah we've now got a cube that's really sort of rustling and tussling and doing some whacky stuff. I'm gonna slow down the frequency of this so we don't see it actively tearing in a weird way as it's going and let's just go through our front view and take a look at what this looks like. We're getting a tear in one direction, a tear in another and that's something. I think I might wanna really increase the amount of rotation for our cube, maybe even go, change the seed value a little bit. There we are. So now we're now getting some really whacky rotations in there and it's just obliterating the cloth. So I'd say that's a pretty decent place for us to start, I'm gonna go to display Gouraud shading and I'm gonna just hide our cube, so I'm gonna hold down the option key, or the Alt key, as I click on this and let's press play and take a look at this finished animation. So as you can see, we're tearing through our cloth getting different results slightly with each and every one of them and if you were to throw in some good textures and some good lighting or moderately okay textures and moderately okay lighting, you'd get something that looked like what we showed you at the very top. So as a quick reminder, what we did is we created our plane, we fixed the points of that plane in the corners with the fix points option, we added a cloth surface object to our cloth so that we can turn on the use tear option and we've got a simple object that's pushing through our planes and I've got a vibrate tag on it just so that it adds enough variation that each one of these breaks is a little bit different from the one that came before.
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