CLAUDE.md

Starter Kit Racing

Port of the Kenney "Starter Kit Racing" Godot 4.6 project to plain JavaScript and three.js with crashcat physics.

Structure

• js/ — JavaScript port
  • main.js — Entry point, scene setup, game loop
  • Physics.js — crashcat wall colliders and sphere body (ported from Godot collision shapes)
  • Track.js — GridMap track layout and piece placement
  • Vehicle.js — Vehicle physics and controls
  • Camera.js — Camera system
  • Controls.js — Input handling
  • Particles.js — Smoke trail effects
  • Audio.js — Sound: positional sources on the vehicle, distance lowpass, outdoor reverb; engine and impacts are synthesized, skid is a sample with tone/pitch variation
  • EngineWorklet.js — Procedural engine synth (AudioWorklet)
  • ImpactSound.js — Procedural collision one-shots (rendered into AudioBuffers at init)
• models/ — GLB models shared between both versions
• audio/ — Sample assets (skid.ogg; engine and impacts are synthesized). The synth DSP cores are plain classes importable from Node for offline rendering/analysis.
• sprites/ — Sprite assets

Key conventions

• GridMap cell size: 9.99 units, scale: 0.75 (CELL_RAW and GRID_SCALE in Track.js)
• Track group has position.y = -0.5 offset
• Godot vehicle models use root_scale = 0.5
• Wall colliders: friction 0.0, restitution 0.1
• Corner colliders: arc center at (-CELL_HALF, +CELL_HALF) in local space, outer wall radius 2*CELL_HALF - 0.25
• Orientation mapping from Godot GridMap indices: { 0: 0°, 10: 180°, 16: 90°, 22: 270° }

Porting reference

Godot collision shapes are defined in _godot/models/Library/mesh-library.tscn as ConcavePolygonShape3D vertex data. The JS port approximates these with crashcat cuboid colliders.