chore(VR): remove dead reprojection code

[alandtse]

Summary by CodeRabbit

• Documentation

  • Clarified stereo reprojection UI label and added a descriptive hover tooltip.

• Refactor

  • Streamlined stereo optimization pipeline and gating so VR reprojection/merge runs only when required resources are ready.
  • Made mode/resource bindings more reliable across frames.

• Chores

  • Adjusted default forward occlusion scale from 0.2 to 0.1 for improved performance.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 8a9689b and 0c2e0a2.

📒 Files selected for processing (7)

• package/Shaders/VRStereoOptimizations/ReprojectionCS.hlsl
• src/Deferred.cpp
• src/Features/VR.h
• src/Features/VR/StereoBlend.cpp
• src/Features/VRStereoOptimizations.cpp
• src/Features/VRStereoOptimizations.h
• src/Globals.cpp

💤 Files with no reviewable changes (1)

• package/Shaders/VRStereoOptimizations/ReprojectionCS.hlsl

🚧 Files skipped from review as they are similar to previous changes (1)

• src/Globals.cpp

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📝 Walkthrough

Walkthrough

The reprojection compute shader and its dispatch were removed; stereo reprojection is replaced by the stereo blend path. New readiness gating and stencil-swap tracking were added; shader/resource compilation and dispatch for reprojection were deleted and related settings/defaults adjusted.

Changes

Cohort / File(s)	Summary
Shader Removal package/Shaders/VRStereoOptimizations/ReprojectionCS.hlsl	Deleted the reprojection compute shader file and its entrypoint/resources.
Deferred / Render Hooks src/Deferred.cpp, src/Globals.cpp	Gated stencil dispatch in StartDeferred() with new culling-ready check; call stereoOpt.NoteStencilSwap() in OMSetDepthStencilState hook; updated a comment referencing stereo overwrite blend pass.
VR Feature Helpers src/Features/VR.h	Added IsStereoOptimizationCullingReady() to centralize readiness checks for stereo optimization/culling.
Stereo Optimization Core src/Features/VRStereoOptimizations.h, src/Features/VRStereoOptimizations.cpp	Removed DispatchReprojection(), reprojection shader/resource management, and reprojection dispatch flow; added CanDispatchStencil() and NoteStencilSwap(); changed Settings::forwardOcclusionScale default from 0.2f → 0.1f; adjusted ImGui label/tooltip to reference stereo reprojection/overwrite blend and removed reprojection shader compilation/clear.
Stereo Blend Usage src/Features/VR/StereoBlend.cpp	VR::DrawStereoBlend() now uses IsStereoOptimizationCullingReady() for decisions; removed the early-return that depended on debugSkipMerge, altering control flow for that case.

Sequence Diagram(s)

sequenceDiagram
    participant Frame
    participant Deferred as Deferred::StartDeferred
    participant VRFeat as globals::features::vr
    participant StereoOpt as VRStereoOptimizations
    participant GPU as GPU/Shaders

    Frame->>Deferred: Begin frame
    Deferred->>VRFeat: globals::features::vr.IsStereoOptimizationCullingReady()
    alt culling ready
        Deferred->>StereoOpt: Dispatch stencil classification
        StereoOpt->>VRFeat: NoteStencilSwap() (via OMSetDepthStencilState hook)
    end
    Frame->>VRFeat: VR::DrawStereoBlend()
    VRFeat->>VRFeat: compute vrStereoOptActive via IsStereoOptimizationCullingReady()
    alt use overwrite blend
        VRFeat->>GPU: Bind overwrite blend CS / resources
        GPU-->>VRFeat: Execute stereo overwrite blend
    else normal blend
        VRFeat->>GPU: Bind normal blend path
        GPU-->>VRFeat: Execute stereo blend
    end

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• feat(vr): reproject stereo #2002: Adds the original ReprojectionCS shader and DispatchReprojection() logic that this PR removes/conflicts with.
• fix(VR): SSGI discrepancies #1926: Introduces stereo-blend/stereo-sync reprojection utilities and shaders that relate to the new blend-based path.
• feat(VR): add edge detection for stereo blending #1948: Modifies stereo reprojection/blend shader selection and related shader behavior, overlapping VR blend changes here.

Suggested reviewers

• doodlum

Poem

🐰
I hopped through frames with curious cheer,
A shader shelved, the blend draws near.
Stencils counted, swaps noted true,
The pipeline hums — a fresher view.
Hooray! 🥕✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 22.22% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: removing the ReprojectionCS.hlsl shader and associated DispatchReprojection() code path from the VR stereo optimization system.

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[github-actions]

No actionable suggestions for changed features.

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/Deferred.cpp`:
- Around line 283-285: DeferredCompositeCS can read stale texPerPixelMode if
DispatchStencil() is skipped; update DeferredPasses() to only bind
texPerPixelMode to slot 16 when the same stencil-readiness gate used to call
DispatchStencil() is true (e.g.
globals::features::vr.IsStereoOptimizationCullingReady() or
stereoOpt.IsStencilActive()), and explicitly bind a null SRV (nullptr) to slot
16 when that gate is false so the compute shader cannot early-out based on stale
data; make this change near the existing stereoMode/texPerPixelMode binding
logic to mirror the DispatchStencil() condition.

In `@src/Features/VR.h`:
- Around line 129-135: The helper IsStereoOptimizationCullingReady must mirror
the actual pass prerequisites: either extend it to include the stencil and blend
resources or create two dedicated checks CanDispatchStencil() and
CanDrawStereoBlend() and use them where DispatchStencil() and DrawStereoBlend()
are called; ensure each check validates REL::Module::IsVR(), stereoOpt.loaded,
stereoOpt.settings.stereoMode != VRStereoOptimizations::StereoMode::Off,
!stereoOpt.settings.debugSkipMerge and the specific DirectX resources (for
stencil: the same resources DispatchStencil() requires; for blend:
stereoBlendOverwriteCS, stereoBlendCopyTex and stereoBlendCB) and return false
if any are null so the outer pipeline never assumes readiness when a later stage
will early-out.

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Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 4e4c6bbf-445e-40be-b6f9-acb0efd8c7a4

📥 Commits

Reviewing files that changed from the base of the PR and between abeb11b and 8a9689b.

📒 Files selected for processing (6)

• package/Shaders/VRStereoOptimizations/ReprojectionCS.hlsl
• src/Deferred.cpp
• src/Features/VR.h
• src/Features/VRStereoOptimizations.cpp
• src/Features/VRStereoOptimizations.h
• src/Globals.cpp

💤 Files with no reviewable changes (1)

• package/Shaders/VRStereoOptimizations/ReprojectionCS.hlsl

[github-actions]

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