Vertex paint: coalesce vertex color uploads during stroke

[fernandotonon]

Summary

• Improve vertex paint stroke performance by coalescing vertex color uploads.
• Instead of committing colors on every mouse-move, schedule a single-shot flush and upload at most once per event loop tick.
• Force a final flush on stroke end to ensure the last sample is visible and captured.

Rationale

On dense meshes, uploading vertex colors every mouse-move can dominate frame time and make the brush feel sticky. This keeps the painting math unchanged while reducing buffer churn.

Test plan

• Enter Edit Mode, enable Vertex Paint.
• Paint continuously over a dense mesh: brush should feel smoother and colors should still update interactively.
• Release mouse: last painted sample should be visible immediately and undo should revert the stroke.

Made with Cursor

Summary by CodeRabbit

• Bug Fixes
  • Improved vertex painting performance by deferring color updates instead of processing them immediately on each brush sample.
  • Enhanced reliability of undo snapshots to ensure painted states are properly captured before editing completes.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

Vertex-paint GPU color commits transition from synchronous to deferred execution. Brush sample changes mark a pending flush flag and schedule commitment via a zero-delay timer, validating edit-mode state before executing. Edit-mode exit clears pending flags, and stroke completion with commit enabled forces immediate flush to capture final state before undo snapshot.

Changes

Cohort / File(s)	Summary
Header Declarations src/EditModeController.h	Added two private boolean flags (m_vertexPaintFlushPending and m_vertexPaintFlushScheduled) to track deferred flush state in vertex-paint operations.
Implementation Logic src/EditModeController.cpp	Refactored vertex-paint commit flow to defer GPU color updates via zero-delay QTimer callback instead of immediate execution; validates edit-mode and pointer validity before commit; clears pending flags on edit-mode exit; forces immediate flush on stroke completion with commit enabled.

Sequence Diagram

sequenceDiagram
    participant Brush as Brush Sample
    participant Controller as EditModeController
    participant Timer as QTimer
    participant GPU as Mesh/GPU Commit
    
    Brush->>Controller: applyVertexColorBrush()
    activate Controller
    Controller->>Controller: Check if flush pending
    alt Flush not scheduled
        Controller->>Timer: Schedule zero-delay callback
        Controller->>Controller: Set m_vertexPaintFlushPending = true
        Controller->>Controller: Set m_vertexPaintFlushScheduled = true
    else Flush already scheduled
        Controller->>Controller: Set m_vertexPaintFlushPending = true
    end
    deactivate Controller
    
    Timer-->>Controller: Callback triggered
    activate Controller
    Controller->>Controller: Validate edit-mode active & pointers valid
    alt Validation passed
        Controller->>GPU: commitVertexColorsToEntity()
        GPU->>GPU: meshDataChanged()
    end
    Controller->>Controller: Clear pending/scheduled flags
    deactivate Controller

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 With brush in paw, I paint so free,
But hold my work—don't rush, you see!
A timer waits with patient care,
Then batches color through the air,
One final stroke, commit with might,
Our painted strokes now set just right! 🎨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main performance optimization: coalescing vertex color uploads during painting strokes instead of committing on every brush sample.
Description check	✅ Passed	The description includes a clear summary of changes, rationale for the optimization, and a practical test plan, but lacks explicit feature/bugfix categorization matching the template.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ 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/vertex-paint-perf

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud