GPU Particles 3D - animate emission points using animation player

[aidandavey]

I wanted to create a particle system which only spawns particles from within the 'inside of a mesh. The mesh is animated. For context, my character will appear to be made of smoke.

There is already a function to generate an emission points texture from a node.

This got me half way, but the shape is not affected by the animations I am applying to the mesh.

I can imagine it's possible to generate the vertex bone data (bone id and normalised weight) and store it in the emission points texture along side the position, then apply the transformations in the process material, similar to how a visual mesh would be animated.

[Calinou]

Thanks for the proposal! Consolidating in #5051.