Fracturing/Breaking Shape Matching Constraints

[saiacide]

Hi there,

Shape Matching constraints aren't described by a single lagrange multiplier. Instead, their use a 3x3 deformation matrix that determines how far away from their "rest state" they are. Unfortunately this is currently not exposed via the API. We will expose these matrices in upcoming updates.

Note that for a fracturing/tearing effect you'd also need to update mesh topology and skinning, which is a far from trivial thing to do.

Thanks that makes sense. I might try and figure out how to expose the deformation matrix while I wait for the update. Once I have the deformation matrix could you give me some hints on how to calculate a stress value from it? The math in the shapematching constraint is pretty hairy but it looks like I would need both the rotation matrix and the deformation matrix.


Is it something like this?

Code:

float4x4 transform = math.mul(R,deformation[i]);
float stress = math.length(math.mul(transform, restComs[i]));

I'm only allowing certain clusters to break and my mesh is pre-fractured which makes updating the skinning significantly easier.