Collision Manager

Central collision detection system implementing multiple collision algorithms for precise vehicle and object interactions in a racing game.

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🎯 Core Responsibilities

Function	Algorithm	Use Case
Vehicle-Track Collision	Grid-based	Off-track detection
Object-Object Collision	SAT (Separating Axis Theorem)	Precise hitbox detection
Raycasting	Line intersection	AI vision/sensors
Path Intersection	Distance-based	Route planning

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🏗️ Constructor

constructor(scalingFactor: number)

Parameter	Type	Description
scalingFactor	number	Grid resolution for track collider

Singleton Pattern:

• Accessed via CollisionManager.instance
• Ensures single collision system instance

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📊 Properties

Property	Type	Description
scalingFactor	number	Track collider grid resolution
_instance	CollisionManager | null	Singleton instance reference

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🛠️ Core Methods

Collision Detection

isCollidingWithTrack()

public isCollidingWithTrack(corners: Vec2D[], trackCollider: number[][]): Vec2D | null

Grid-based track boundary detection:

1. Converts world to grid coordinates
2. Checks all vehicle corners
3. Returns first collision point

isCollidingWithAnotherObject()

public isCollidingWithAnotherObject(object1: CollisionObject | Vec2D[], object2: CollisionObject): boolean

SAT implementation for precise hitbox detection:

1. Gets rotated corners
2. Calculates separation axes
3. Projects shapes
4. Checks overlaps

Raycasting

rayCastFromController()

rayCastFromController(
  controller: PhysicsBasedController,
  length: number,
  angleOffset: number,
  debug: boolean = false
): Vec2D | null

Casts ray from vehicle:

• Checks opponents and obstacles
• Returns closest intersection
• Optional debug visualization

Path Analysis

getActualPathIntersections()

getActualPathIntersections(
  actualPath: CheckPoint[],
  sampledPoints: CheckPoint[],
  controllerToSkip: OpponentController
)

Finds obstacles along AI path:

• Uses SOME_ARBITRARY_THRESHOLD (100 units)
• Returns intersection segments

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⚙️ Supporting Methods

Geometry Utilities

Method	Description
getRotatedCorners()	Calculates oriented bounding box
getAxes()	Gets separation axes for SAT
projectPolygon()	Projects shape onto axis
overlaps()	Checks projection overlap

Spatial Query

Method	Description
getGridPosition()	World-to-grid conversion
circleOverlapsWithTrack()	Circular area check

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🧠 Algorithm Details

Separating Axis Theorem (SAT)

graph TD
    A[Get Rotated Corners] --> B[Calculate Axes]
    B --> C[Project Shapes]
    C --> D[Check Overlaps]
    D --> E{All Axes Overlap?}
    E -->|Yes| F[Collision]
    E -->|No| G[No Collision]

Track Collision Grid

• 2D array representing drivable areas
• 0 = drivable, 1 = collision
• Scaled by scalingFactor

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🏎️ Usage Examples

Basic Collision Check

const corners = getCarCorners(position, width, height, angle);
const collisionPoint = collisionManager.isCollidingWithTrack(corners, trackCollider);

Object Collision

if (collisionManager.isCollidingWithAnotherObject(car1, car2)) {
  physicsDriver.handleCollision(car1, car2);
}

AI Raycasting

const obstacle = collisionManager.rayCastFromController(aiCar, 200, 0, true);

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⚠️ Edge Cases

1. Undefined Objects:

   • Skipped in raycasting/path checks
   • Commented frustration about array pollution :)

2. Grid Boundaries:

   • Explicit bounds checking
   • Returns collision for out-of-bounds

3. Boost Perks:

   • Specifically excluded from path checks

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🛠️ Performance Considerations

1. Grid Resolution:

   • Higher scalingFactor = coarser checks
   • Balance precision vs performance

2. SAT Optimization:

   • Early exit on first separating axis
   • Cached axes where possible

3. Raycasting:

   • Limited to essential objects
   • Debug mode adds overhead

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📈 Extension Points

1. Spatial Partitioning:

   • Add quadtree for opponent checks

2. Collision Layers:

   • Implement category filtering

3. Damage Zones:

   • Extend track collider values