Hi there.
I’m having problems with my models folding un-naturally when I pose their armature. Is there a way round this? I’m told that you can add more bones “to hold things still” but I’m not really having any luck with that. Ar their any diagrams and suchlike online with tips on avoiding folding?
If you mean that something like the inside of an elbow of the back of a knee creasing and shrinking when you bend the armature than yes, it is a problem.
Solutions include,
1: Adding loops either side of the joint and carefully weight-painting the area. In most cases this won’t solve the problem completely but on toon models it’s a simple fix.
2: Adding a small bone at the joint and weight-painting it to the area around it so that it influences how those verts can move. Because it stays still, it tries to hold the verts in place and therefore tends to reduce the amount by which they can disappear into the joint.
3: Adding a shape key at the joint and driving it with the rotating bone. When the bone is rotated, the shape key would swell the verts that would normally shrink into the joint so that, in effect, they stay put.