example - gaussian compute nodes

[mosure]

• add better infrastructure for creating custom gaussian shader nodes (these are already pretty friendly but common use cases would benefit from more factory behavior to lower entry overhead - see src/morph/interpolate.rs)
• example highlights factory compute node implementation, see https://sparkjs.dev/examples/#splat-shader-effects

[teodosin]

Some weeks ago I managed to hack together a GPU version of my mesh-to-gaussian conversion. It's my first successful attempt at a custom render node, so it's unpolished but a good example of a use case for this feature. Linking it as prior art: https://github.com/teodosin/bevy_gen_gaussian/blob/main/src/gaussian/gpu_mesh_to_gaussians.rs

My 2 cents: I think this feature/example would benefit from being plugged in late in the render pipeline and having access to the full rendered scene with skinned and shaded meshes. For example, my goal for my game is to make use of as much of the existing mesh infra as possible and then do a compute pass which converts each shaded triangle into a gaussian. So I'm not reinventing the wheel in terms of skeletons, shading, and LOD. I'm imagining that a good generic implementation would use change detection to differentiate between static and dynamic meshes and detect LOD changes, but I'm not sure what that would look like. Future work after that could be also being able to sample the textures of the meshes to generate splats more densely while still having them attached to moving triangles.