# lofivor - build roadmap

survivor-like optimized for weak hardware. finding the performance ceiling first, then building the game.

## phase 1: sandbox stress test

- [x] create sandbox.zig (separate from existing game code)
- [x] entity struct (x, y, vx, vy, color)
- [x] flat array storage for entities
- [x] spawn entities at random screen edges
- [x] update loop: move toward center, respawn on arrival
- [x] render: filled circles (4px radius, cyan)
- [x] metrics overlay (entity count, frame time, update time, render time)
- [x] controls: +/- 100, shift +/- 1000, space pause, r reset

## phase 2: find the ceiling

- [x] test on i5-6500T / HD 530 @ 1280x1024
- [x] record entity count where 60fps breaks
- [x] identify bottleneck (CPU update vs GPU render)
- [x] document findings

findings (AMD Radeon test):
- 60fps breaks at ~5000 entities
- render-bound: update stays <1ms even at 30k entities, render time dominates
- individual drawCircle calls are the bottleneck

## phase 3: optimization experiments

based on phase 2 results:

- [x] batch rendering via texture blitting (10x improvement)
- [x] ~~if cpu-bound: SIMD, struct-of-arrays, multithreading~~ (not needed)
- [x] re-test after each change

findings:
- texture blitting: pre-render circle to texture, drawTexture() per entity
- baseline: 60fps @ ~5k entities
- optimized: 60fps @ ~50k entities, 30fps @ 100k entities
- see journal.txt for detailed benchmarks

## phase 4: add collision

- [ ] spatial partitioning (grid or quadtree)
- [ ] projectile-to-enemy collision
- [ ] measure new ceiling with collision enabled

## phase 5: game loop

- [ ] player entity (keyboard controlled)
- [ ] enemy spawning waves
- [ ] player attacks / projectiles
- [ ] enemy death on hit
- [ ] basic game feel

## future

- [ ] different enemy types
- [ ] player upgrades
- [ ] actual game design (after we know the constraints)