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; ```
41 lines
1.0 KiB
WebGPU Shading Language
41 lines
1.0 KiB
WebGPU Shading Language
#import bevy_pbr::mesh_bindings mesh
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#import bevy_pbr::mesh_functions mesh_position_local_to_clip
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#import bevy_render::instance_index
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struct CustomMaterial {
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color: vec4<f32>,
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};
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@group(1) @binding(0)
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var<uniform> material: CustomMaterial;
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struct Vertex {
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@builtin(instance_index) instance_index: u32,
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@location(0) position: vec3<f32>,
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@location(1) blend_color: vec4<f32>,
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};
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struct VertexOutput {
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@builtin(position) clip_position: vec4<f32>,
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@location(0) blend_color: vec4<f32>,
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};
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@vertex
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fn vertex(vertex: Vertex) -> VertexOutput {
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var out: VertexOutput;
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out.clip_position = mesh_position_local_to_clip(
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mesh[bevy_render::instance_index::get_instance_index(vertex.instance_index)].model,
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vec4<f32>(vertex.position, 1.0),
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);
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out.blend_color = vertex.blend_color;
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return out;
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}
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struct FragmentInput {
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@location(0) blend_color: vec4<f32>,
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};
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@fragment
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fn fragment(input: FragmentInput) -> @location(0) vec4<f32> {
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return material.color * input.blend_color;
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}
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