GameEngine 🎮

A SwiftUI-native 2D game engine for building simple games. Built for clarity and ease of use.

✨ Quick Start

1. Add to your project

// In Package.swift
dependencies: [
    .package(url: "path/to/GameEngine", branch: "main")
]

2. Create your first game

import SwiftUI
import GameEngine

class SimpleScene: GameScene {
    override func setup() {
        let ball = Ball(at: CGPoint(x: 100, y: 100))
            .bouncy()
            .color(.red)
        ball.setScreenSize(screenSize)
        addGameObject(ball)
    }
}

struct ContentView: View {
    var body: some View {
        GameView(scene: SimpleScene())
    }
}

🎯 Core Concepts

GameScene

Create a custom scene by subclassing GameScene:

class MyGameScene: GameScene {
    override func setup() {
        // Create your game objects here
        let player = Ball(at: CGPoint(x: 100, y: 100))
        addGameObject(player)
    }
    
    override func update(deltaTime: Double) {
        super.update(deltaTime: deltaTime)
        // Custom game logic here
    }
    
    override func handleInput(at location: CGPoint) {
        // Handle taps/clicks
    }
}

GameObjects

GameObjects represent things in your game:

Ball(at: CGPoint(x: 100, y: 100))
    .size(width: 20, height: 20)
    .color(.blue)
    .bouncy()

Built-in GameObjects

• Ball - Circles with physics
• Box - Rectangles for platforms, obstacles
• GameText - Display text

Custom GameObjects

class Bullet: GameObject {
    override func update(deltaTime: Double) {
        position.y -= 300 * deltaTime
        if position.y < 0 {
            isActive = false
        }
    }
    
    override func render(context: GraphicsContext) {
        let rect = CGRect(origin: position, size: size)
        context.fill(Path(rect), with: .color(.yellow))
    }
}

🎮 Camera & Scrolling

override func update(deltaTime: Double) {
    super.update(deltaTime: deltaTime)
    
    // Follow player
    camera.follow(player, smoothing: 0.1)
    
    // Constrain to bounds
    camera.constrainTo(bounds: levelBounds)
    
    // Zoom (clamped between 0.1 and 10.0)
    camera.zoom = 2.0
    
    // Shake effect
    camera.shake(intensity: 10, duration: 0.5)
}

💥 Collision Detection

Basic collision check:

for other in scene.gameObjects {
    if self.intersects(with: other) {
        // Handle collision
    }
}

Optimized nearby search:

// Only check objects within radius (much faster!)
for nearby in scene.findNearby(self, radius: 100) {
    if self.intersects(with: nearby) {
        // Handle collision
    }
}

Find specific types:

for enemy in scene.findGameObjects(ofType: Enemy.self) {
    if player.intersects(with: enemy) {
        // Handle collision
    }
}

🏗️ Layer System

Control render order with layers (lower = behind, higher = in front):

background.layer = -2
ground.layer = -1
player.layer = 0
bullets.layer = 1
ui.layer = 10

📱 Platform Support

• ✅ iOS 16+
• ✅ macOS 13+
• ✅ 60fps game loop
• ✅ Touch event input

🤝 Philosophy

Simple, clear, easy to understand. No magic, no complexity.

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Made for SwiftUI developers who want to make simple 2D games.