An AI-generated hand that could not take the rig
The first model, made with AI, was no good for rigging, but it was enough to build and test the glass and the fabric.
To get going quickly, the first hand was an AI-generated model (Rodin): a left hand with forearm, about 6,000 vertices and textured.
To rig it I use Python scripts for Blender. The mesh came split into seven pieces along the UV seams, so it first had to be welded. Then, since it was smooth and did not show the knuckles, the joints were placed with slices of the mesh and anatomical proportions, and the weights were computed automatically.
That is where the problem showed up: the mesh was not made to deform. It had too many triangles, with no vertex loops at the joints. Bending a finger folded half the palm, the pinky dragged the edge of the hand almost down to the wrist and the base of the thumb sank when it rotated. Fixing the weights improved some things, but a fist was impossible.
Even so, it let me move forward with everything else while I looked for a better mesh:
- the frosted glass, with the blur depending on the hand's distance
- the fabric that stretches when the hand goes through the glass, with compute shaders