WebXR over WebGPU: XRGPUBinding session glue and two-pass stereo - #5
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WebXR over WebGPU: XRGPUBinding session glue and two-pass stereo#5octopusburrow wants to merge 3 commits into
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…acros Newer emdawnwebgpu packages add a WGPUStringView message parameter to WGPUQueueWorkDoneCallback (4 params: status, message, userdata1, userdata2); earlier packages use 3 (no message). The signature is a property of the Dawn package each emsdk release pins, so no clean version macro exists — and macro PRESENCE does not discriminate: both generations define WGPU_STRLEN/WGPUStringView (verified against Dawn v20260423.175430 [4-param] and the earlier package in this fork's deploy toolchain [3-param]). So: provide both signatures as overloads of _fence_work_done_callback and let the assignment to the port's own WGPUQueueWorkDoneCallback typedef select the matching one. The 4-param overload is additionally guarded on WGPU_STRING_VIEW_INIT for hypothetical pre-StringView headers. The dispatch pattern compiles against both package generations (verified standalone on both toolchains); a full engine build is verified on the 3-param toolchain. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…check Vendored as patches/0007 per the thirdparty/tint/patches/ convention. This is a Group B (Specialization Constants) patch, completing the capability this fork introduced in 0002 and extended in 0003/0005: Godot's specialization constants change effective struct and array sizes at runtime, so a spec-constant-sized array leaves the containing struct's Size() at its unfolded value and the validator's TOTAL-size check (str->Size() < cur_offset) fires on IR that the fork's own 0002 rationale already classifies as valid-by-construction. 0002 relaxed the per-MEMBER size check for this exact producer; this patch applies the same capability to the struct-total check a few lines below it. Without this, the Mobile renderer's scene shader (depth shadow atlas + sampler UBO with spec-constant-sized arrays) fails Tint validation and every lit 3D scene renders black on Dawn/Windows, including this fork's own sample projects. Unshaded scenes are unaffected, which is why the gap survived: the fork's Windows TODO note and this failure are the same bug. Layer choice: an alternative would be changing Godot's shader generation so emitted SPIR-V never carries the mismatch, touching no vendored code. This fork already faced that choice for the member-size case and chose validator relaxation, three times (0002, 0003, 0005, documented as Group B in patches/README.md); this patch follows the established architecture rather than opening a second front. If Group B is ever re-architected toward shader-gen fixes, this check belongs in that migration with the rest of the group. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Adds immersive WebXR support to the WebGPU backend on the web platform. Build: the WebXR module was hard-gated on opengl3; this allows it to build in webgpu=yes/opengl3=no configurations (config.py). The gate is the only thing that changes for non-WebGPU builds. Runtime: binds the XR session via XRGPUBinding (not XRWebGLBinding) when the engine runs on the WebGPU driver, and renders stereo as two single-view passes into the layers of the XR texture array, since WebGPU has no multiview extension. The per-view path is opt-in via XRInterface::needs_per_view_passes() (defaults false), so every existing XR backend — WebGL/WebXR included — takes the unchanged single/multiview path. WebGL-XR behavior is unchanged: it continues to use XRWebGLBinding and the operator-supplied WebXR Layers polyfill exactly as before.
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Adds working immersive-vr on the WebGPU driver:
webgpu=yes; theold opengl3 gate predates WebGPU XR and matches stock Godot).
XRGPUBindingsession setup (requires thewebgpusession feature). Theprojection layer is created ONCE as a texture-array for immersive-vr: the previous
build-mono-then-rebuild-on-first-pose path cost a measured ~10s of session startup on
desktop Chrome (swapchain allocate/teardown/allocate, and a mid-session layer swap the
WebXR-WebGPU spec currently leaves undefined).
pass into its layer of the XR texture array.
Behavior on WebGL sessions is functionally unchanged — the stereo-from-start default is
gated to WebGPU immersive-vr, and handheld AR keeps the upstream 1-view fallback on both
backends. (Two diagnostics added during development fired spuriously on WebGL paths;
both are now gated to the WebGPU binding.)
Dependencies and disclosures:
WebGPU.importJsTexture.engine.jsnow requestsxrCompatible: trueadapters for WebGPU builds; WebIDLignores unknown dictionary members so this is inert on non-XR browsers, but on
multi-GPU systems it can influence adapter selection (caller-provided adapters are
honored unchanged). Newer Chrome enforces the spec's xrCompatible requirement
(
XRGPUBindingthrows InvalidStateError without it), so this is load-bearing, nothygiene.
view_slice_cache); >2-view devices would needa small extension.
work duplicated); a follow-up PR shares them across the two passes.
Verified end-to-end on desktop Chrome + SteamVR: session entry (instant, vs ~10s before
the single-allocation fix), correct per-eye stereo projection, exit and re-entry. Known
limitation: no depth submission (the layer declares none; Chromium currently submits no
depth on any path). immersive-ar alpha handling is future work, noted in-code.
Comfort note: desktop-PCVR WebGPU sessions on current release Chrome exhibit a
compositor-side pose-drift artifact unrelated to this PR (Chromium missed a swap-chain
sync token; tracked at mrdoob/three.js#34343, affects all WebGPU-XR content). Fixed
upstream in CL 8275843 (merged 2026-08-25, ships in M154 — Canary/Dev today); we
verified the fix resolves it on this code path.