Physics is a fundamental aspect of most games, enabling realistic movement, collisions, gravity, and interactions between objects. Phaser, as a powerful game framework, provides built-in physics engines that make it easy to add these behaviors to your games.
In this section, you will learn:
- What game physics is and why it matters
- The different physics systems available in Phaser
- How to choose the right physics system for your game
- Basic concepts and terminology used in game physics
- What is Game Physics?
Game physics simulates the laws of physics within a game world. This includes:
- Movement: How objects move and accelerate.
- Collisions: How objects interact when they touch or overlap.
- Forces: Effects like gravity, friction, and impulses.
Why is it important?
- Adds realism and immersion to games.
- Enables dynamic and interactive gameplay.
- Makes it easier to implement features like jumping, bouncing, or sliding.
- Physics Systems in Phaser
Phaser supports multiple physics engines, each with its own features and use cases. The main ones are:
| Physics System | Description | Use Cases | Complexity |
|---|---|---|---|
| Arcade Physics | Simple, fast, and easy to use. Focuses on basic collisions and velocity. | Platformers, shooters, simple games | Beginner |
| Matter.js | Advanced, full-featured 2D physics engine. Supports complex shapes, constraints, and realistic physics. | Puzzle games, simulations, games with complex interactions | Intermediate/Advanced |
| Impact | Another physics engine, less commonly used. | Games ported from ImpactJS | Intermediate |
Note: Most beginners start with Arcade Physics due to its simplicity.
- Key Physics Concepts
Before diving into code, let's clarify some essential terms:
- Body: The physical representation of a game object (e.g., a sprite) in the physics world.
- Velocity: The speed and direction at which a body moves.
- Acceleration: The rate at which velocity changes.
- Gravity: A force that pulls bodies in a specific direction (usually down).
- Collision: When two bodies touch or overlap, triggering a response.
- Enabling Physics in Phaser
To use physics in Phaser, you need to:
- Choose a physics system in your game configuration.
- Enable physics on game objects (like sprites).
- Configure properties such as gravity, velocity, and collision behavior.
Example: Setting Up Arcade Physics
Let's see how to enable Arcade Physics in a Phaser game.
const config = {
type: Phaser.AUTO,
width: 800,
height: 600,
physics: {
default: 'arcade', // Use Arcade Physics
arcade: {
gravity: { y: 300 }, // Apply gravity downwards
debug: true // Show physics bodies for debugging
}
},
scene: {
preload: preload,
create: create,
update: update
}
};
const game = new Phaser.Game(config);
function preload() {
this.load.image('player', 'assets/player.png');
}
function create() {
// Add a sprite and enable physics on it
this.player = this.physics.add.sprite(100, 450, 'player');
// Set bounce and collision with world bounds
this.player.setBounce(0.2);
this.player.setCollideWorldBounds(true);
}
function update() {
// Game logic goes here
}Explanation:
- The
physicsproperty in the config enables Arcade Physics. gravity: { y: 300 }applies gravity to all physics-enabled objects.this.physics.add.spritecreates a sprite with a physics body.setBouncemakes the sprite bounce when it hits surfaces.setCollideWorldBoundsprevents the sprite from leaving the game area.
- Exercise: Enable Physics on a Sprite
Task:
Create a Phaser scene where a ball sprite falls due to gravity and bounces when it hits the bottom of the screen.
Starter Code
const config = {
type: Phaser.AUTO,
width: 400,
height: 300,
physics: {
default: 'arcade',
arcade: {
gravity: { y: 500 },
debug: true
}
},
scene: {
preload: preload,
create: create
}
};
const game = new Phaser.Game(config);
function preload() {
this.load.image('ball', 'assets/ball.png');
}
function create() {
// Your code here
}Solution
function create() {
// Add the ball sprite with physics enabled
this.ball = this.physics.add.sprite(200, 50, 'ball');
// Make the ball bounce when it hits surfaces
this.ball.setBounce(0.8);
// Prevent the ball from leaving the game area
this.ball.setCollideWorldBounds(true);
}Common Mistakes & Tips:
- Make sure the image path is correct (
assets/ball.png). - If the ball doesn't bounce, check the
setBouncevalue (should be between 0 and 1). - If the ball falls through the bottom, ensure
setCollideWorldBounds(true)is set.
Summary
- Game physics simulates real-world behaviors like movement, gravity, and collisions.
- Phaser offers multiple physics engines; Arcade Physics is best for beginners.
- Enabling physics involves configuring the game and adding physics-enabled objects.
- You practiced enabling physics and making a sprite bounce with gravity.
Next:
In the next section, you'll learn how to enable physics on different types of sprites and interact with them in your game.
Phaser - Game Development with JavaScript
Module 1: Introduction to Game Development and Phaser
- What is Game Development?
- Overview of Phaser
- Setting Up Your Development Environment
- Your First Phaser Project
Module 2: Phaser Basics
- Understanding the Game Loop
- Game Configuration and Scenes
- Loading and Displaying Images
- Working with Text
- Handling Input (Keyboard and Mouse)
Module 3: Sprites and Animation
Module 4: Game Physics and Interactivity
- Introduction to Physics in Phaser
- Enabling Physics on Sprites
- Collisions and Overlaps
- Interactive Objects and Events
