💥 Collision Detection
Master AABB, circle, SAT, and advanced collision detection algorithms for professional games!
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Introduction to Collision Detection
Section 1 of 9
Collision detection is essential for making games feel interactive and realistic. It determines when objects in your game touch, overlap, or collide with each other. **Why Collision Detection Matters:** • Core gameplay mechanic (hitting enemies, collecting items, blocking obstacles) • Physics interactions (bouncing, stopping, sliding) • Game boundaries (keeping player inside the level) • Trigger zones (starting events, changing areas) **Common Use Cases:** • Player vs Enemies/Obstacles • Projectiles vs Targets • Player vs Collectibles • Platforms vs Character feet • Trigger zones for events **Performance Considerations:** Checking every object against every other object is expensive! For 100 objects, that's 4,950 checks per frame. We need efficient algorithms. **Types We'll Cover:** 1. AABB (Axis-Aligned Bounding Box) - Fast, simple rectangles 2. Circle Collision - Perfect for round objects 3. Point vs Shape - Mouse clicks, projectiles 4. SAT (Separating Axis Theorem) - Rotated rectangles 5. Pixel-Perfect - Most accurate, slowest
Code Example:
// Basic collision detection structure
class GameObject {
constructor(x, y, width, height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
}
// Check if this object collides with another
collidesWith(other) {
// We'll implement different methods here
return false;
}
}
// Game loop with collision checking
const player = new GameObject(100, 100, 50, 50);
const enemies = [
new GameObject(200, 150, 40, 40),
new GameObject(300, 200, 40, 40)
];
function update() {
// Check collisions
enemies.forEach(enemy => {
if (player.collidesWith(enemy)) {
console.log('Hit enemy!');
handleCollision(player, enemy);
}
});
}
function handleCollision(obj1, obj2) {
// Response: damage, bounce, collect, etc.
console.log('Collision detected!');
}💡 Tip: Try this code in your browser console (F12 → Console).