Support gl_InstanceIndex in shaders #1262
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I think this is a reasonable workaround for now. Thanks! |
rparrett
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Jan 27, 2021
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In order to write useful shaders for instanced rendering it's necessary to have access to the gl_InstanceIndex builtin. Bevy's current shader reflection incorrectly identifies gl_InstanceIndex as a vertex attribute, preventing it from being used. This skips gl_InstanceIndex in the reflection code in the same way that gl_VertexIndex is already being skipped.
A more complete solution might be to enumerate all glsl builtins rather than just special casing them as needed but I decided to keep this change minimal because this seemed like code that was likely to be rewritten soon anyway. If someone thinks it's worth expanding to the more general version, I'm happy to do that in this PR.