Hi everyone, I’m currently getting my feet wet with modelling fat characters in Blender and I’m using separate cage meshes with a cloth simulation modifier to try to get realistic jiggle. The problem I’m having is that the cage mesh on the upper arms sags through where the arm bones would be unless I turn the pressure up really high. But when I do that, the mesh becomes pretty firm and doesn’t jiggle the way I want it to. Is there any way I can keep the vertices on the physics cage at least a certain distance away from the middle of the arm without affecting the simulation too much? I thought about using a separate collider mesh inside the arm, but that seems like it would cause more issues than it would solve. Any advice?
It is hard to say without seeing the size of the character, what sort of settings you are using for the proxy mesh or what kinda animation you are trying to do. There are a few things you could try.
First thing I would look at is the pin group for the proxy mesh. You could add some weight painting to help support the arms so they don’t sag. Try a low strength brush and add weight to the pin group to the parts that don’t need to jiggle as much. Parts near the wrist, elbow and shoulder which tend to be where the fat isn’t as thick could be weight painted more heavily
You could try increasing the shinking factor under the shape section in the cloth physics, though it make the arm less jiggly.
But without seeing a picture, it is a bit difficult to say anything concrete
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Here’s what the character’s arm currently looks like. In retrospect, I probably shouldn’t have modelled them hanging down that much and left that up to the physics simulation, but it is what it is.
The cage mesh goes from the elbow to the shoulder.
These are the main settings I’m using. The mesh is pinned at 1 strength to the arm bone on the armature at the elbow and shoulder. I turned the pressure up higher which mostly solved the issue of the mesh sagging through the arm, but that also made it feel a bit too firm for my liking. It looks okay for big motions but for smaller movements it’s basically rigid.
I had considered using some lower strength pinning on the top of the arm, but if the arm was ever in a different orientation (like if the character was lying down for example) then it would be pinning the wrong section of the mesh, so that didn’t seem suitable.
That being said, I did notice there was a “Vertex Weight Proximity” modifier that adjusts the weights in a vertex group based on their proximity to a target object, so perhaps I could add a new mesh object to the bone and increase the weight of the pin group in relation to its proximity to that? If the pinning feature works how I think it does, it should be fighting to return the vertex to its original position as it gets closer to the target object and the vertex weight increases, and it should work regardless of the orientation of the arm.
EDIT: This seems to be a bust. The Vertex Weight Proximity modifier has to be above the Cloth modifier for it to do anything, but then it doesn’t respond to deformations in the mesh caused by the Cloth modifier. So it only accounts for the shape of the cage mesh in its initial position. Basically no different from just applying a pin group normally.
Don’t know if you’ve already seen this guide, given that it looks like you already have an idea on making the models, but here’s something I hope gives inspiration at least for continuing this endeavor:
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I had not seen this, but it doesn’t really seem to fit with what I’m trying to achieve here. I want to have reasonably realistic fat simulation within Blender rather than making a model fatter/slimmer in a way that works in a game engine. The thought is appreciated, but I don’t think I’ll be using this.
Hadn’t realized I forgot about that post; here’s something that might be a bit more fitting:
They even have an animation to demonstrate their work.