The Project | About Us | Contribute | Donations | License
HOME My courses Completed
◄ Previous
◄

Introduction to Physics in Phaser

Next ►
►

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

  1. 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.

  1. 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.

  1. 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.

  1. Enabling Physics in Phaser

To use physics in Phaser, you need to:

  1. Choose a physics system in your game configuration.
  2. Enable physics on game objects (like sprites).
  3. 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 physics property in the config enables Arcade Physics.
  • gravity: { y: 300 } applies gravity to all physics-enabled objects.
  • this.physics.add.sprite creates a sprite with a physics body.
  • setBounce makes the sprite bounce when it hits surfaces.
  • setCollideWorldBounds prevents the sprite from leaving the game area.

  1. 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 setBounce value (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.

◄ Previous
◄
Next ►
►
The Project | About Us | Contribute | Donations | License
© Copyright 2024. All rights reserved