UNASSIGNED-CoreValidation-Shader-OutputNotConsumed warning

djeedai / bevy_hanabi

🎆 Hanabi — a GPU particle system plugin for the Bevy game engine.

Apache License 2.0

906 stars 72 forks source link

UNASSIGNED-CoreValidation-Shader-OutputNotConsumed warning #20

Open marshauf opened 2 years ago

marshauf commented 2 years ago

Hello,

when running 2D or 3D examples (0e1df4d9f712907e1c1ae10f77478221247f7f72), bevy warns about a performance problem:


2022-04-11T18:17:01.846362Z  WARN wgpu_hal::vulkan::instance: PERFORMANCE [UNASSIGNED-CoreValidation-Shader-OutputNotConsumed (0x609a13b)]
        Validation Performance Warning: [ UNASSIGNED-CoreValidation-Shader-OutputNotConsumed ] Object 0: handle = 0x984b920000000104, type = VK_OBJECT_TYPE_SHADER_MODULE; | MessageID = 0x609a13b | Vertex attribute at location 1 not consumed by vertex shader    
2022-04-11T18:17:01.846425Z  WARN wgpu_hal::vulkan::instance:   objects: (type: SHADER_MODULE, hndl: 0x984b920000000104, name: ?) 
``

djeedai commented 2 years ago

I'm not sure what's that (I don't have it locally, probably I need to install something to get the validation layers). I suspect it's because currently we always output a mesh with UVs, but if there no image/texture we don't use those attributes. We should definitely optimize this though, even if that's not related to the current warning.

djeedai commented 2 years ago

Ah yes I remember, this is commented out currently because we use a fixed ParticleVertex layout for convenience, but would otherwise need to dynamically populate a buffer either with or without those UVs, which makes the vertex buffer a bit less convenient to manipulate (the type of vertices is not known at compile time anymore).

djeedai commented 1 year ago

Note: found how to enable validation layers, and confirming I can repro. However I'm less sure why this happens now that I've looked quickly at it. But with a repro it should be easier to fix.

djeedai commented 1 year ago

Ok this is actually a limitation of the current design, notes for self:

ParticlesRenderPipeline unconditionally adds the vertex_uv to VertexBufferLayout::attributes, which is where the validation warning is coming from when not using textures, because the render shader then never reads that attribute
ParticleVertex is defined with unconditional UV coordinates, matching the attribute layout, and would need to become a runtime-sized "struct"
EffectsMeta contains a BufferVec<ParticleVertex> with an element size fixed at build time
That buffer needs to hold per-input-kind data (so, based on vertex layout, but also the actual vertex content to support e.g. triangles or hexagons or generic mesh / point cloud based emitter)