CNA-BUG-114: WEBGPU always creates a Depth24PlusStencil8 back-buffer depth attachment but PresentationParameters keeps the requested DepthFormat

CNA snapshot 3b43bd86  ·  Known Issues › Current bugs  ·  source links pinned to 3b43bd86

RecreateDepthTexture always uses Depth24PlusStencil8 and the renderer has no applied-format override, so PresentationParameters.DepthStencilFormat reports the requested format instead of the attachment that exists.

Identifier

CNA-BUG-114

Category

Bug

Subsystem

Graphics & renderers

Status

Open

Verified against

CNA 3b43bd86 (3b43bd8687ed46523d873f9bec4b32bd8481dcb5)

Severity

Low (a triage suggestion, not a project priority)

Evidence basis

Source-verified: read at TARGET, not executed

Tests touching this area

Yes: see Current tests

Affected contract

PresentationParameters.DepthStencilFormat after device creation/Reset on WEBGPU

Expected behaviour

CNA writes the applied formats back into PresentationParameters through GetAppliedDepthStencilFormatEXT (NormalizeAppliedPresentationFormats in GraphicsDevice.cpp); SDL_GPU and FNA3D override it.

Actual behaviour at TARGET

WebGPURenderer.cpp's RecreateDepthTexture always requests WGPUTextureFormat_Depth24PlusStencil8, and the WebGPU renderer overrides only the applied MSAA count and back-buffer colour format, so the requested depth format is echoed. A game that asked for Depth24 is told it has no stencil (Clear with Stencil throws InvalidOperationException, stencil state is validated against a format that does not match the hardware), and one that asked for None is told it has no depth buffer.

Source locations

• modules/renderers/webgpu/src/WebGPURenderer.cpp — WebGPURenderer::RecreateDepthTexture
• modules/renderers/webgpu/include/CNA/Internal/Renderers/WebGPU/WebGPURenderer.hpp — overrides GetAppliedMultiSampleCountEXT and GetAppliedBackBufferFormatEXT, not GetAppliedDepthStencilFormatEXT
• modules/graphics/src/Xna/GraphicsDevice.cpp — NormalizeAppliedPresentationFormats

Evidence

Checked by reading the named sources at 3b43bd86; nothing was built or executed for this entry. Whether the device's stencil gating consults PresentationParameters or HasRealBackBufferStencilBuffer on WEBGPU was not traced; the reported format is wrong either way.

Focused reproduction

No focused reproduction is known. Nothing has been invented here; the evidence above is what exists.

Current tests

BackBufferFormatContractTests.cpp covers the applied back-buffer colour format; no WEBGPU test compares the reported depth format with the attachment that exists.

Regression test

A WEBGPU applied-formats test that requests Depth24 and None and expects the depth format actually created.

Blast radius

Games that read PresentationParameters.DepthStencilFormat to decide on stencil techniques on WEBGPU.

Workaround

Request Depth24Stencil8 explicitly on WEBGPU.