Add SpatialHash class for efficient spatial queries on entities:
- New SpatialHash.h/cpp with bucket-based spatial hashing
- Grid.entities_in_radius(x, y, radius) method for O(k) queries
- Automatic spatial hash updates on entity add/remove/move
Benchmark results at 2,000 entities:
- Single query: 16.2× faster (0.044ms → 0.003ms)
- N×N visibility: 104.8× faster (74ms → 1ms)
This enables efficient range queries for AI, visibility, and
collision detection without scanning all entities.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Benchmark suite measuring entity performance at scale:
- B1: Entity creation (measures allocation overhead)
- B2: Full iteration (measures cache locality)
- B3: Single range query (measures O(n) scan cost)
- B4: N×N visibility (the "what can everyone see" problem)
- B5: Movement churn (baseline for spatial index overhead)
Key findings at 2,000 entities on 100×100 grid:
- Creation: 75k entities/sec
- Range query: 0.05ms (O(n) - checks all entities)
- N×N visibility: 128ms total (O(n²))
- EntityCollection iteration 60× slower than direct iteration
Addresses #115, addresses #117🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
