I started getting involved with vector and matrix math and wanted to understand the math involved in creating a delta shape for a corrective pose.

I think I understand the problem and what needs to be done. I just can’t seem to get it right.

For simplicity, I skinned up a plane to symbiolize an arm with an edge at the elbow. I’m only concerned with one vertex at the elbow for the moment. This vertex is bound to the lower arm with a value of 1. Only the elbow joint is rotated.

I’m not sure I have it all down, but my reasoning is that I need to get that joint’s transformation matrix and the vertex local position. Then also the weight value. I’ve made it easy since I have it bound only to one joint for now. But the actual math still eludes me. If someone could point me in the right direction, I’d be very grateful.

The idea here is that I want to get the matrix to transform the locator from the first position to the one where the arm is posed. Then I’m thinking I should get the inverse of that and move all the vertices back in bind pose for the corrective shape that has been made.