Alpha Blending / Transparency

[bonsairobo]

As of writing, the vertex pulling renderer does not support alpha blending for several reasons:

• vertex pulling optimizations (3-face index buffer) preclude backface culling
• vertex pulling selection of visible faces may be "wrong" when the chosen face is a "back face"
  • the face will be alpha blended, but it should be culled entirely

For these reasons, alpha blending is currently disabled in the vertex pulling pipeline (using BlendState::REPLACE).

If we are going to support transparency, I think it should happen in its own pipeline, or at least a specialized pipeline. There will need to be some big changes to the index buffering as well as the shader code.

[bonsairobo]

RE #2 , I will still reserve a byte for alpha in any color mode, but it may go unused for a while.