Skeletal Animation

[voxelias]

Hello World! I am working on skeletal animation implementation for Bevy. My first goal is to have working example demonstrating one animation loaded from a GLTF file.

The plan is:

• Extend Mesh asset with joints_indices (up to 4 indices of joints affecting a point in 3D space) and joints_weights (up to 4 weights affecting a point in 3D space) attributes, that shall be passed to the shader.
• Extend GLTF loader with joints and weights loading
• Prepare an Animation Assset that will contain keyframes and transformations for joints
• Prepare a shader, that will take joints_indices and joints_weights from VAO and transformations from the uniform
• Prepare an animation system that will calculate approximate transformations between two keyframes and pass them as a uniform to the shader
• Prepare an animation loader. I want to do it inside of a startup system for now, because the question about extending/rewriting of the assets system is still open
• Bring all together in a new example code

Please, let me know what you think? I am new to Bevy and just started with the engine research and may doing something from the wrong end.

[StarArawn]

This sounds really good! I think eventually we'll want to use a compute shader to calculate animations, but currently it's not practical to use compute in bevy.

[zicklag]

Just curious, in a short, high-level description, what makes it impractical at the moment?

[StarArawn]

Bevy doesn't support compute shaders yet.

[cart]

I agree that your points all sound good! I think in the immediate short term it makes sense to build the animation part specifically for skeletal animation, but at some point i think it would be interesting to build it into bevy's eventual "unified animation system".

[TheButlah]

This update from the 0.6 blog post made me very happy :)

Skeletal Animation: Ultimately Bevy will have a general purpose, property based animation system (we already have a working implementation). We've been holding off on adding skeletal animation, so we can slot it in to that system, but in retrospect that was a mistake. People need skeletal animation now. In the short term we will build a scoped 3d skeletal animation system, just to get the ball rolling. Then later we will port it to the general purpose system (whenever that is ready),