PT-6/7/8: skinned meshes in the TLAS, real motion vectors, correctness oracle

[proggeramlug]

Summary

Closes the three headline gaps left after the PT roadmap:

• PT-6 - skinned meshes enter the TLAS. Skinning lived only in the vertex shader, so characters were ghosts to every ray. A compute pre-skin pass now poses each drawn skinned mesh into its PT-megabuffer window (world space - the palette bakes placement, so TLAS instances are identity), per-slot BLASes rebuild each frame from those windows (intersection and hit shading share bytes via first_vertex/first_index), and the instance list extends past the scene nodes. Lumen HW probes see the same instances, so characters contribute to GI too. Also fixes a latent TLAS-capacity bug (recreate when the instance count outgrows the built capacity - wave spawns grow it mid-run).
• PT-7 - real skinned motion vectors. No previous-frame joint palette existed anywhere; skinned draws wrote exactly zero velocity (TAA/TSR ghosting) and invalidated their own PT history every frame. The palette is now double-buffered (keyed by the FFI anim handle, offsets in lockstep), the scene VS reconstructs last frame''s world position through the EN-022 velocity-reference VP, and the PT kernel reprojects through the velocity MRT when it is non-zero (TAA''s convention), falling back to the camera matrix otherwise.
• PT-8 - the correctness oracle. Two golden-image tests run the real engine headless on a ray-query device: converged progressive (transport regressions) and realtime-under-camera-motion (reprojection regressions of the prev_vp-transpose class that survived three human review rounds). Skip cleanly without RT hardware. The oracle caught a real bug before it was committed: the kernel RNG was seeded from taa_frame_index, which freezes when TAA is off - progressive accumulation silently never converged (300 frames = 1 frame). PT now keeps its own rolling frame counter.

Verified on the 760M: debug-6 traced view shows the skinned player with interpolated normals (first skinned mesh ever to appear in a traced image); debug-20 history heat shows no rejection hole on animating characters; all 9 golden tests pass; RT gameplay clean at ~19-24 fps.

Docs: docs/pt/PT-6-7-8-skinned-tlas-motion-oracle.md.

https://claude.ai/code/session_018574BdCfSjdpNK3WLgx1hP

Summary by CodeRabbit

• New Features

  • Added path-tracing support for animated, skinned characters, including dynamic ray-traced shadows and global illumination.
  • Improved motion reprojection for skeletal and character movement, producing smoother temporal results.
  • Added progressive and realtime path-tracing rendering coverage for improved visual correctness.

• Bug Fixes

  • Prevented animation clips from unexpectedly restarting during transitions.
  • Improved path-tracing history stability and accumulation consistency.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 15433bbe-2f90-4d11-a74f-3e604e2926c8

📥 Commits

Reviewing files that changed from the base of the PR and between eebf2f2 and 6692dae.

⛔ Files ignored due to path filters (2)

• native/shared/tests/golden/pt_progressive.png is excluded by !**/*.png
• native/shared/tests/golden/pt_realtime_motion.png is excluded by !**/*.png

📒 Files selected for processing (12)

• .gitignore
• docs/pt/PT-6-7-8-skinned-tlas-motion-oracle.md
• native/shared/src/ffi_core/models.rs
• native/shared/src/ffi_core/ragdoll_ffi.rs
• native/shared/src/models.rs
• native/shared/src/renderer/mod.rs
• native/shared/src/renderer/model_draw.rs
• native/shared/src/renderer/pt_pass.rs
• native/shared/src/renderer/shaders/core.rs
• native/shared/src/renderer/shaders/mod.rs
• native/shared/src/renderer/shaders/pt.rs
• native/shared/tests/golden_render.rs

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📝 Walkthrough

Walkthrough

Adds dynamic skinned meshes to path-tracing acceleration structures, tracks previous joint poses for motion vectors, introduces velocity-based PT reprojection, separates PT frame sequencing from TAA, and adds ray-query golden tests.

Changes

Skinned PT pipeline

Layer / File(s)	Summary
Previous-pose staging and animation wiring native/shared/src/ffi_core/models.rs, native/shared/src/ffi_core/ragdoll_ffi.rs, native/shared/src/models.rs, native/shared/src/renderer/mod.rs, native/shared/src/renderer/model_draw.rs	Animation uploads use keyed previous-palette pairing; current and previous joint palettes are staged and uploaded separately, while repeated clip requests remain no-ops during fades.
Dynamic skinned TLAS population native/shared/src/renderer/mod.rs, native/shared/src/renderer/model_draw.rs, native/shared/src/renderer/shaders/pt.rs, native/shared/src/renderer/shaders/mod.rs	Skinned cached meshes retain bind-pose data, register dynamic draws, run compute pre-skinning, rebuild dynamic BLASes, and append dynamic instances to the TLAS.
Skinned motion vectors and PT reprojection native/shared/src/renderer/shaders/core.rs, native/shared/src/renderer/shaders/pt.rs, native/shared/src/renderer/pt_pass.rs, native/shared/src/renderer/mod.rs, native/shared/src/renderer/model_draw.rs	Previous skinned positions generate velocity MRT data; PT reprojection uses raster velocity with prev_vp fallback, and PT sampling advances with pt_frame_index.
Ray-query oracle and supporting documentation native/shared/tests/golden_render.rs, .gitignore, docs/pt/PT-6-7-8-skinned-tlas-motion-oracle.md	Adds progressive and realtime-motion ray-query goldens, skips unsupported environments, ignores DXC runtime DLLs, and documents the pipeline and validation workflow.

Estimated code review effort: 4 (Complex) | ~60 minutes

Sequence Diagram(s)

sequenceDiagram
  participant SkinnedDraw
  participant Renderer
  participant PreSkin
  participant TLAS
  participant PT
  SkinnedDraw->>Renderer: register dynamic skinned draw
  Renderer->>PreSkin: write posed vertices to PT megabuffer
  PreSkin->>TLAS: provide updated BLAS geometry
  TLAS->>PT: expose skinned instances for ray queries
  Renderer->>PT: bind raster velocity and advance PT frame index
  PT->>PT: reproject using velocity or prev_vp

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Possibly related PRs

• Bloom-Engine/engine#86: Overlaps the staged skinned pose and joint-offset plumbing.
• Bloom-Engine/engine#91: Provides related DXC setup for ray-query golden tests.
• Bloom-Engine/engine#92: Shares PT pass plumbing updated here for frame sequencing and velocity binding.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/pt6-skinned-tlas

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