Performance Optimization: Canvas Viewport Culling & Stroke Chunking

[bchou9]

Feature Description

Implement viewport-based rendering optimization to dramatically improve performance for canvases with thousands of strokes by only rendering visible elements.

Problem Statement

Current rendering issues with large canvases:

• All strokes rendered on every frame, even if off-screen
• Performance degrades significantly with >1000 strokes
• Canvas becomes sluggish with complex drawings
• Memory usage grows linearly with stroke count
• No spatial indexing for efficient lookup

Performance Benchmarks (Before)

• 100 strokes: 60 FPS ✅
• 1,000 strokes: 30 FPS ⚠️
• 5,000 strokes: 8 FPS ❌
• 10,000+ strokes: Unusable ❌

Target Performance (After)

• 100 strokes: 60 FPS ✅
• 1,000 strokes: 60 FPS ✅
• 5,000 strokes: 55+ FPS ✅
• 10,000+ strokes: 50+ FPS ✅

Proposed Solutions

1. Spatial Indexing with QuadTree

Implement efficient spatial data structure for fast stroke lookup.

2. Viewport Culling Manager

Only render strokes within visible viewport plus small margin.

3. Optimized Rendering Loop

Selective rendering based on visibility calculations.

4. Stroke Chunking for Network Transfer

Send strokes in chunks, prioritizing visible areas.

5. Progressive Loading

Load only viewport-visible strokes initially, lazy-load rest.

Benefits

• 10x Performance Improvement for large canvases
• Smooth 60 FPS even with 10,000+ strokes
• Reduced memory footprint
• Faster initial load times
• Better mobile performance
• Scalable to massive collaborative sessions