Make 2D Games with Tiniest2D

Collision System

How It Works

• Every object has an AABB (Axis-Aligned Bounding Box) based on its sprite size
• Sprites can have custom collider bounds (set in Sprite Editor)
• Collision is checked every frame for dynamic objects

Collision Types Explained

1. None - Object is completely ignored by collision system
2. Static - Acts as an immovable wall (use for terrain, platforms)
3. Dynamic - Moves and gets pushed out of other colliders (use for player, enemies)
4. Trigger - Detects overlap but doesn't block movement (use for collectibles, zones)

Collision Resolution

• Dynamic objects are automatically pushed out of Static and other Dynamic objects
• Triggers never block movement - they only detect overlaps

The onCollision Callback

The onCollision(objA, objB) function is called when objects overlap. The callback patterns are:

Key rules:

• objA is always either Dynamic or Trigger
• When two Dynamic objects collide, both get a callback (each as objA)
• When two Triggers overlap, one callback is generated (first trigger as objA)
• Static objects never appear as objA

Example: Detecting Different Collision Types

func onCollision(objA, objB) {
    var typeA = getCollisionType(objA)
    var typeB = getCollisionType(objB)

    // Player (dynamic) touching a coin (trigger)
    if (getName(objA) == "player" && typeB == COLLISION_TRIGGER()) {
        print("Collected!")
        removeObject(gameScene, objB)
    }

    // Two triggers overlapping (e.g., detection zones)
    if (typeA == COLLISION_TRIGGER() && typeB == COLLISION_TRIGGER()) {
        print(getName(objA) + " entered " + getName(objB) + "'s zone")
    }

    // Player hit by enemy (both dynamic)
    if (getName(objA) == "player" && getName(objB) == "enemy") {
        print("Player hit!")
    }
}

Physics System

Tiniest Engine has a built-in physics system that handles gravity and velocity automatically for dynamic objects.

How Physics Works

Every frame, the engine automatically:

1. Applies scene gravity to each dynamic object's velocity
2. Applies velocity to each dynamic object's position

// Physics pipeline (handled automatically by engine):
velocity += gravity * dt
position += velocity * dt

Setting Up Gravity

Set gravity on a scene to make dynamic objects fall:

func start() {
    // Set downward gravity (300 pixels per second squared)
    setGravityY(gameScene, 300)

    // Optional: horizontal gravity (wind effect)
    setGravityX(gameScene, 0)

    setScene(gameScene)
}

Using Velocity

Control objects using velocity instead of directly setting position:

var player = Object("player")
var jumpForce = -200  // Negative = upward

func start() {
    setCollisionType(player, COLLISION_DYNAMIC())
    addObject(gameScene, player)
    setGravityY(gameScene, 300)
    setScene(gameScene)
}

func onUpdate(dt) {
    // Horizontal movement via velocity
    if (isKeyHeld(KEY_LEFT())) {
        setVelocityX(player, -100)
    } else if (isKeyHeld(KEY_RIGHT())) {
        setVelocityX(player, 100)
    } else {
        setVelocityX(player, 0)
    }

    // Jump by setting upward velocity
    if (isKeyPressed(KEY_SPACE())) {
        setVelocityY(player, jumpForce)
    }
}

Physics Functions

Important: Only COLLISION_DYNAMIC() objects are affected by gravity and have their velocity applied automatically