Optimize performance, add textures, mobile controls, and production polish

[devin-ai-integration]

Summary

Massive overhaul of index.html to make Chungi Hunter 3D production-ready: big perf fixes, procedural textures, real mobile support, and gameplay polish. No external assets are required — all new textures are generated procedurally at runtime.

Performance (the big wins)

• Analytical terrain height (O(1)) replaces the old per-frame getTerrainHeight() that iterated all 6,561 grid points for every entity. This alone removed ~70k ops per frame across player/8 bots/chungi/camera.
• InstancedMesh for scenery: grass (500), stones (100), tree trunks (45), and tree foliage (~1,125 spheres) are now drawn in just a handful of draw calls instead of ~1,700.
• Device-adaptive quality: on mobile / low-CPU devices the game auto-reduces pixel ratio, shadow map size, floor tessellation, cloud/grass/stone/tree counts, and canopy density.
• Auto FPS fallback: if FPS drops below ~28 for a sustained period, the game drops to "low" quality and turns off shadows automatically.
• Tab-hidden pause: the render/physics loop halts when the tab is hidden, saving battery on mobile.

Textures

• Added a procedural canvas-texture system that generates defaults for:
  • Floor grass (radial gradient + noise)
  • Tree bark (vertical grain)
  • Leaves (layered greens, vertex-color tinted per tree)
  • Stone wall (brick pattern)
  • Rocks (noise)
  • Character armor (panel + rivets)
  • Chungi (subtle weave)
• Textures uploaded via portal.html continue to override the procedural defaults exactly as before.

Mobile

• Robust mobile detection (UA + maxTouchPoints + viewport width) sets a body.is-mobile class.
• Larger, thumb-friendly action buttons, bigger pause button, scaled HUD at mobile widths.
• Mobile-only hint banner shown briefly on match start.
• Haptic feedback (navigator.vibrate) on jump, dash, throw, bot elimination, player hit, and victory.

Production polish

• 3-hit health bar with invulnerability frames, red screen flash, and chungi knockback — replaces the old one-shot death.
• Score system with per-elimination points (+100), survival bonus on victory, persistent best-score in localStorage.
• Minimap (canvas, ~10 Hz) showing bots, chungi, player facing, and water.
• FPS counter HUD (green/amber/red tiers) that also drives adaptive quality.
• Persistent graphics settings (quality, shadows, camera distance) in localStorage, restored on load.
• Loading overlay that fades out once the first frame renders.
• Memory cleanup: eliminated bots dispose their geometries; obstacles no longer retain full THREE.Group references.

Review & Testing Checklist for Human

• Open the game on desktop and confirm FPS 60 at default quality; the FPS counter should stay green.
• Open on a phone (or DevTools mobile emulation) and confirm the action buttons are big enough, the minimap is visible, and there are no visual regressions.
• Verify portal.html texture uploads still override the new procedural defaults (floor/wall/tree/player/bot/chungi).
• Play a full round: take 3 hits and confirm GAME OVER fires only on the 3rd; eliminate all 8 bots and confirm the VICTORY screen shows the score including the survival bonus.
• Refresh and confirm the best score, graphics quality, shadow quality, and camera distance are restored from the previous session.

Notes

• No dependencies were added; everything runs on the same Three.js <script> already in index.html.
• Line endings in index.html were normalized from CRLF to LF as part of the edit; portal.html was intentionally left as-is to keep the diff focused.
• The old terrainHeights grid array is gone — terrain height is now purely analytical and matches the generated mesh exactly.

Link to Devin session: https://app.devin.ai/sessions/5b14cc25db654389a1752fce6fbdfb83
Requested by: @alimohomad

[devin-ai-integration]

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