feat(xr): WebGPU multiview frame pass, XR bridge, and clustered lights

[mvaligursky]

Overview

Implements per-eye WebGPU XR rendering via a FramePassMultiView wrapper integrated with the frame graph and forward renderer, extends WebGPU XR bridge/device state for sub-images and cleanup, and ensures clustered lighting assignment runs for passes inside the multiview wrapper. Updates the xr-views test example and related WebGPU debug labeling.

Changes:

• Add FramePassMultiView to run child frame passes once per XR view with device/backbuffer XR state.
• Extend FrameGraph with multiview begin/end helpers and pass-merge rules that treat the wrapper as atomic.
• Forward renderer: schedule stereo passes into multiview when appropriate; fix multiview detection to read XR from CameraComponent; guard unsupported depth/post paths.
• WebGPU: XR bridge sub-image population, xrSubImages / xrColorTextureViewDescriptor / _clearXrState behavior; framebuffer color view creation and debug labels for XR vs context paths.
• WorldClustersAllocator: unwrap FramePassMultiView when assigning clusters so inner render actions get lightClusters before forward passes run.
• xr-views.example.mjs: expanded harness for multiview / composite testing.

Public API: None intended; new types and device fields are @ignore engine internals.

Examples: examples/src/examples/test/xr-views.example.mjs updated.

[Copilot]

Pull request overview

This PR adds a WebGPU-focused XR stereo rendering path by introducing a FramePassMultiView wrapper that replays captured frame passes once per XR view, integrating that wrapper into the frame graph and forward renderer scheduling. It also extends the WebGPU XR bridge/device state to expose per-view sub-image data (including view descriptors for layered textures) and updates clustered-light assignment to work correctly for passes captured inside the multiview wrapper.

Changes:

• Added FramePassMultiView and FrameGraph.beginMultiView/endMultiView to capture and replay passes per XR view while keeping frame-graph pass merging safe.
• Updated ForwardRenderer scheduling to wrap eligible stereo XR blocks, and updated the per-view draw loop to render only the active view when a wrapper is iterating.
• Extended WebGPU XR state (xrSubImages, xrColorTextureViewDescriptor, _clearXrState) and updated the XR views example to visualize multiview output on WebGPU.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/scene/renderer/world-clusters-allocator.js	Unwraps FramePassMultiView so clustered lighting gets assigned to child passes’ render actions.
src/scene/renderer/frame-pass-multi-view.js	New wrapper pass that iterates XR sub-images per view and replays child passes.
src/scene/renderer/forward-renderer.js	Wraps eligible camera/layer blocks in multiview scopes and restricts per-view rendering to the active eye when iterating.
src/scene/frame-graph.js	Adds multiview capture scope plumbing and compiles wrapper children with existing optimizations.
src/platform/graphics/webgpu/webgpu-xr-bridge.js	Populates per-view XR sub-image info (including optional view descriptors) and centralizes XR state clearing.
src/platform/graphics/webgpu/webgpu-render-target.js	Creates framebuffer color views using the XR per-eye view descriptor when applicable and improves labels.
src/platform/graphics/webgpu/webgpu-graphics-device.js	Adds XR multiview state fields and implements _clearXrState().
examples/src/examples/test/xr-views.example.mjs	Expands the XR views harness for WebGPU array-layer rendering + composite visualization.

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