gijs_pong/.planning/phases/01-foundation/01-02-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, key-decisions, patterns-established, requirements-completed, duration, completed

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	key-decisions	patterns-established	requirements-completed	duration	completed
01-foundation	02	ui	canvas physics ball-movement collision-detection zone-deflection vanilla-js game-loop	phase provides 01-01 index.html scaffold with HiDPI canvas, GameLoop, Renderer, Input, Physics skeleton, GameState	GameConfig object with initialBallSpeed (220px/s), speedIncrement (18px/s), paddleSpeed (400px/s) Physics.serveBall() serving from center at random angle and direction Physics.update() with full ball movement via vx/vy * deltaTime Wall bounce: top and bottom with Math.abs vy inversion Out-of-bounds detection: ball re-serves automatically when exiting left/right edge Physics._checkPaddleCollision() with 5-zone AABB deflection and per-hit speed increment On-canvas speed debug display for Phase 1 verification	Phase 2 Phase 3 Phase 4 Phase 5	added patterns Zone-based paddle deflection: 5 zones mapped to [-60, -30, 5, 30, 60] degrees AABB collision detection with ball-radius buffer on all four sides Ball pushed out of paddle post-collision to prevent double-collision on next frame GameConfig as tunable constants object: allows per-value adjustment without touching Physics logic serveBall() serves at random angle (-45 to +45 deg) in random horizontal direction Speed stored as scalar on ball.speed; vx/vy recomputed from speed + angle each paddle hit	created modified index.html	Angles [-60, -30, 5, 30, 60] degrees: center zone uses 5 degrees (not 0) to prevent infinite horizontal loops Speed increments on every paddle hit via GameConfig.speedIncrement=18 px/s; resets to initialBallSpeed=220 on serve Collision only checked when ball.vx < 0 (moving left toward paddle1): eliminates false positives when ball passes through after deflection Ball pushed to paddle.x + paddle.width + ball.radius + 1 post-collision: 1px safety margin prevents double-trigger Tunneling risk documented in comment: risk begins above 4800px/s; current rallies top out ~800px/s; Phase 5 can add substep if needed Debug speed display kept for Phase 1 manual verification (costs nothing, aids confirmation)	Physics methods added to Physics object without disturbing existing structure: serveBall(), _checkPaddleCollision() added alongside update() GameConfig placed before GameState at script top: all tunable values centralized, readable before any system references them	CORE-01 CORE-02 CORE-03 CORE-04	1min	2026-03-10

Phase 1 Plan 02: Ball Physics Summary

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

Performance

• Duration: 1 min
• Started: 2026-03-10T13:49:45Z
• Completed: 2026-03-10T13:51:12Z
• Tasks: 2
• Files modified: 1

Accomplishments

• Ball moves from center at 220px/s initial speed in a random direction on page load and after every out-of-bounds
• Wall bounce (top and bottom) with angle-of-incidence = angle-of-reflection via Math.abs vy inversion
• Paddle collision with 5-zone deflection: top edge deflects at -60 deg, center at 5 deg, bottom edge at 60 deg
• Speed increases by 18px/s per paddle hit and resets to 220px/s on every serve
• On-canvas debug display shows current speed in real-time for Phase 1 verification

Task Commits

Each task was committed atomically:

1. Task 1: Ball physics — movement, wall bounce, serve, and GameConfig - 46b8f7b (feat)
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)

Plan metadata: (docs commit follows)

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.

Files Created/Modified

• /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()

Decisions Made

• 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.
• 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.
• 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.
• 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.

Deviations from Plan

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.

Issues Encountered

None.

User Setup Required

None - no external service configuration required. Open index.html directly in any modern browser to play.

Next Phase Readiness

Phase 1 is complete. All 6 success criteria are met:

• CORE-01: Ball moves continuously and bounces off top/bottom walls
• CORE-02: Player 1 paddle deflects ball on collision
• CORE-03: Zone-based angle deflection produces 5 visually distinct trajectories
• CORE-04: Speed increments per hit (visible in debug display), resets per serve
• CORE-07: W/S keys move paddle responsively (from Plan 01-01)
• VFX-05: Canvas renders sharply on HiDPI/Retina displays (from Plan 01-01)

Phase 2 should extend Physics without touching zone deflection logic:

• Add GameState.paddle2 with AI movement
• Add scoring state and reset logic
• Add second AABB collision in _checkPaddleCollision() or a symmetric _checkPaddle2Collision()
• The serveBall() function is already direction-agnostic (random left/right) — no changes needed for 2-player bouncing

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Phase: 01-foundation Completed: 2026-03-10