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

CNA snapshot 009d40f5  ·  Known Issues › Current bugs  ·  source links pinned to 009d40f5

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 009d40f5 (009d40f5dd085c4e674d3479675fac84b12b3e0a)

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 (and SDL_RENDERER)

Expected behaviour

CNA writes the applied formats back into PresentationParameters through GetAppliedDepthStencilFormatEXT (NormalizeAppliedPresentationFormats in GraphicsDevice.cpp); VULKAN does so since VULKAN-348.

Actual behaviour at TARGET

WebGPURenderer.cpp's RecreateDepthTexture always requests WGPUTextureFormat_Depth24PlusStencil8, and the WebGPU renderer overrides only the applied MSAA count, 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. SDL_RENDERER, which has no depth buffer at all, similarly echoes a requested Depth24 (see CNA-GAP-014).

Source locations

• modules/renderers/webgpu/src/WebGPURenderer.cpp — WebGPURenderer::RecreateDepthTexture
• modules/renderers/webgpu/include/CNA/Internal/Renderers/WebGPU/WebGPURenderer.hpp — overrides GetAppliedMultiSampleCountEXT only
• modules/graphics/src/Xna/GraphicsDevice.cpp — NormalizeAppliedPresentationFormats

Evidence

Checked by reading the named sources at 009d40f5; 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

Vulkan_AppliedFormats covers VULKAN; no WEBGPU equivalent exists.

Regression test

Register the applied-formats fixture for WEBGPU (and SDL_RENDERER), expecting the formats actually created.

Blast radius

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

Workaround

Request Depth24Stencil8 explicitly on WEBGPU.