ae98af98df
- Add 01-02-SUMMARY.md documenting physics implementation, GameConfig, zone angles, and Phase 2 extension notes - Update STATE.md: Phase 1 complete (2/2 plans), add decisions 8-10 for zone angles/GameConfig/vx-vy decomposition - Update ROADMAP.md: Phase 1 progress shows 2/2 plans complete - Mark CORE-01, CORE-02, CORE-03, CORE-04 complete in REQUIREMENTS.md Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
125 lines
6.6 KiB
Markdown
125 lines
6.6 KiB
Markdown
---
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phase: 01-foundation
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plan: 02
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subsystem: ui
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tags: [canvas, physics, ball-movement, collision-detection, zone-deflection, vanilla-js, game-loop]
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# Dependency graph
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requires:
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- phase: 01-01
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provides: "index.html scaffold with HiDPI canvas, GameLoop, Renderer, Input, Physics skeleton, GameState"
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provides:
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- "GameConfig object with initialBallSpeed (220px/s), speedIncrement (18px/s), paddleSpeed (400px/s)"
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- "Physics.serveBall() serving from center at random angle and direction"
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- "Physics.update() with full ball movement via vx/vy * deltaTime"
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- "Wall bounce: top and bottom with Math.abs vy inversion"
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- "Out-of-bounds detection: ball re-serves automatically when exiting left/right edge"
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- "Physics._checkPaddleCollision() with 5-zone AABB deflection and per-hit speed increment"
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- "On-canvas speed debug display for Phase 1 verification"
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affects: [Phase 2, Phase 3, Phase 4, Phase 5]
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# Tech tracking
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tech-stack:
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added: []
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patterns:
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- "Zone-based paddle deflection: 5 zones mapped to [-60, -30, 5, 30, 60] degrees"
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- "AABB collision detection with ball-radius buffer on all four sides"
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- "Ball pushed out of paddle post-collision to prevent double-collision on next frame"
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- "GameConfig as tunable constants object: allows per-value adjustment without touching Physics logic"
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- "serveBall() serves at random angle (-45 to +45 deg) in random horizontal direction"
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- "Speed stored as scalar on ball.speed; vx/vy recomputed from speed + angle each paddle hit"
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key-files:
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created: []
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modified: [index.html]
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key-decisions:
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- "Angles [-60, -30, 5, 30, 60] degrees: center zone uses 5 degrees (not 0) to prevent infinite horizontal loops"
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- "Speed increments on every paddle hit via GameConfig.speedIncrement=18 px/s; resets to initialBallSpeed=220 on serve"
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- "Collision only checked when ball.vx < 0 (moving left toward paddle1): eliminates false positives when ball passes through after deflection"
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- "Ball pushed to paddle.x + paddle.width + ball.radius + 1 post-collision: 1px safety margin prevents double-trigger"
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- "Tunneling risk documented in comment: risk begins above 4800px/s; current rallies top out ~800px/s; Phase 5 can add substep if needed"
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- "Debug speed display kept for Phase 1 manual verification (costs nothing, aids confirmation)"
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patterns-established:
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- "Physics methods added to Physics object without disturbing existing structure: serveBall(), _checkPaddleCollision() added alongside update()"
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- "GameConfig placed before GameState at script top: all tunable values centralized, readable before any system references them"
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requirements-completed: [CORE-01, CORE-02, CORE-03, CORE-04]
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# Metrics
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duration: 1min
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completed: 2026-03-10
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---
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# Phase 1 Plan 02: Ball Physics Summary
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**Ball physics with 5-zone angle deflection, per-hit speed increment from 220px/s, wall bounce, and automatic re-serve on out-of-bounds — Phase 1 fully playable**
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## Performance
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- **Duration:** 1 min
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- **Started:** 2026-03-10T13:49:45Z
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- **Completed:** 2026-03-10T13:51:12Z
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- **Tasks:** 2
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- **Files modified:** 1
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## Accomplishments
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- Ball moves from center at 220px/s initial speed in a random direction on page load and after every out-of-bounds
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- Wall bounce (top and bottom) with angle-of-incidence = angle-of-reflection via Math.abs vy inversion
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- Paddle collision with 5-zone deflection: top edge deflects at -60 deg, center at 5 deg, bottom edge at 60 deg
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- Speed increases by 18px/s per paddle hit and resets to 220px/s on every serve
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- On-canvas debug display shows current speed in real-time for Phase 1 verification
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## Task Commits
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Each task was committed atomically:
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1. **Task 1: Ball physics — movement, wall bounce, serve, and GameConfig** - `46b8f7b` (feat)
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2. **Task 2: Paddle-ball collision refinement and speed acceleration verification** - included in Task 1 (angles, tunneling comment, and debug display all implemented together; no additional code changes needed)
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**Plan metadata:** (docs commit follows)
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_Note: Task 2 was purely verification — angles from the plan spec were correct as implemented, tunneling comment was added in Task 1, and debug display was already present. No separate commit needed._
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## Files Created/Modified
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- `/home/dabit/projects/gijs/index.html` - Added GameConfig, Physics.serveBall(), full Physics.update() with ball movement and wall bounce, Physics._checkPaddleCollision() with 5-zone deflection; added on-canvas speed debug display in GameLoop.main()
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## Decisions Made
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- **5-degree center zone:** Zone 2 angle is 5 degrees, not 0 degrees. A perfectly horizontal ball would never reach the opposite wall; the 5-degree slope keeps rallies finite.
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- **vx/vy recomputed from speed + angle per hit:** After each collision, ball.vx and ball.vy are fully recomputed from the new speed and the zone angle. This keeps speed and direction cleanly separated — avoids compound rounding drift from repeated scaling.
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- **Collision guard on vx < 0:** Paddle collision is only checked when ball is moving toward paddle1 (vx < 0). This eliminates false positives on the frame immediately after deflection when ball.x is still near paddle edge.
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- **1px safety margin post-collision:** Ball is pushed to `paddle.x + paddle.width + ball.radius + 1` after collision. The extra 1px ensures the ball starts the next frame clearly outside the paddle bounds regardless of floating-point edge cases.
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## Deviations from Plan
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None - plan executed exactly as written. Task 2 required no code changes; all verification elements (angle table, tunneling comment, debug display) were implemented correctly in Task 1.
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## Issues Encountered
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None.
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## User Setup Required
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None - no external service configuration required. Open index.html directly in any modern browser to play.
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## Next Phase Readiness
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Phase 1 is complete. All 6 success criteria are met:
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- CORE-01: Ball moves continuously and bounces off top/bottom walls
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- CORE-02: Player 1 paddle deflects ball on collision
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- CORE-03: Zone-based angle deflection produces 5 visually distinct trajectories
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- CORE-04: Speed increments per hit (visible in debug display), resets per serve
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- CORE-07: W/S keys move paddle responsively (from Plan 01-01)
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- VFX-05: Canvas renders sharply on HiDPI/Retina displays (from Plan 01-01)
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Phase 2 should extend Physics without touching zone deflection logic:
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- Add `GameState.paddle2` with AI movement
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- Add scoring state and reset logic
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- Add second AABB collision in `_checkPaddleCollision()` or a symmetric `_checkPaddle2Collision()`
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- The `serveBall()` function is already direction-agnostic (random left/right) — no changes needed for 2-player bouncing
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---
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*Phase: 01-foundation*
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*Completed: 2026-03-10*
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