ruffle/render/wgpu/uniforms.md

Information

We are limited to 4 binding groups per pipeline due to GLES-3.1 minimum required limits. There's no specific limit to how many items per group, only per entire pipeline or shader.

For best performance, we should draw as much as possible using the same bound groups before switching groups away. For that reason, group 0 should change less than group 1, which should change less than group 2, etc.

Ideal render pass

An ideal render pass looks like this:

• Set group 0
  • Set group 1
    • Set group 2
      • Draw draw draw
    • Set group 2
      • Draw draw draw
  • Set group 1
    • Set group 2
      • Draw draw draw

Shared

Group 0: Render pass globals

These should be set for the whole render pass and be immutable during it.

Index	Type	Description
0	uniform	View matrix

Group 1: Mesh transforms

These should be set for the current mesh being rendered.

Index	Type	Description
0	uniform	World matrix and color adjustments

Bitmaps

Group 2: Texture transforms

Index	Type	Description
0	uniform	Transformation matrix of the texture
1	texture_2d	Texture to be drawn
2	sampler	Sampler used for the texture

Gradient

Group 2: Texture transforms

Index 1 is a storage buffer when supported by the device, or a uniform buffer otherwise. Storage buffers are more efficient and waste less memory, but are not as widely supported (ie WebGL)

Index	Type	Description
0	uniform	Transformation matrix of the gradient
1	uniform or storage	Gradient information, colors etc