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c1a5428f8e
naga and wgpu should polyfill WGSL instance_index functionality where it is not available in GLSL. Until that is done, we can work around it in bevy using a push constant which is converted to a uniform by naga and wgpu. # Objective - Fixes #9375 ## Solution - Use a push constant to pass in the base instance to the shader on WebGL2 so that base instance + gl_InstanceID is used to correctly represent the instance index. ## TODO - [ ] Benchmark vs per-object dynamic offset MeshUniform as this will now push a uniform value per-draw as well as update the dynamic offset per-batch. - [x] Test on DX12 AMD/NVIDIA to check that this PR does not regress any problems that were observed there. (@Elabajaba @robtfm were testing that last time - help appreciated. <3 ) --- ## Changelog - Added: `bevy_render::instance_index` shader import which includes a workaround for the lack of a WGSL `instance_index` polyfill for WebGL2 in naga and wgpu for the time being. It uses a push_constant which gets converted to a plain uniform by naga and wgpu. ## Migration Guide Shader code before: ``` struct Vertex { @builtin(instance_index) instance_index: u32, ... } @vertex fn vertex(vertex_no_morph: Vertex) -> VertexOutput { ... var model = mesh[vertex_no_morph.instance_index].model; ``` After: ``` #import bevy_render::instance_index struct Vertex { @builtin(instance_index) instance_index: u32, ... } @vertex fn vertex(vertex_no_morph: Vertex) -> VertexOutput { ... var model = mesh[bevy_render::instance_index::get_instance_index(vertex_no_morph.instance_index)].model; ``` |
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