Developing a Cross-Platform Mobile Game with React Native and Phaser #GameDev #ReactNative #Phaser

Table of Contents

Day 2: Creating a Game Loop and Handling User Input in Phaser

Welcome to Day 2 of building a cross-platform mobile game using React Native and Phaser. Yesterday, we set up Phaser inside a React Native WebView. Today, you’ll create a basic game loop, handle user interactions like touch/tap, and display a moving sprite.

🧠 What You’ll Learn

Creating a game loop with Phaser’s update() function
Handling mobile touch and pointer input
Moving a sprite on tap
Structuring Phaser code for scalability

🔁 Step 1: Update the HTML Game Template

Replace assets/phaser/game.html with the following code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8" />
  <title>Phaser Game</title>
  <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/phaser.js"></script>
  <style>
    body { margin: 0; overflow: hidden; }
    canvas { display: block; }
  </style>
</head>
<body>
<script>
  let logo;
  let targetX = 160;
  let targetY = 240;

  const config = {
    type: Phaser.AUTO,
    width: 320,
    height: 480,
    scene: {
      preload,
      create,
      update,
    }
  };

  function preload() {
    this.load.image('logo', 'https://labs.phaser.io/assets/sprites/phaser3-logo.png');
  }

  function create() {
    logo = this.add.image(targetX, targetY, 'logo').setInteractive();

    this.input.on('pointerdown', function (pointer) {
      targetX = pointer.x;
      targetY = pointer.y;
    });
  }

  function update() {
    if (!logo) return;

    const speed = 4;
    const distX = targetX - logo.x;
    const distY = targetY - logo.y;

    if (Math.abs(distX) > 1 || Math.abs(distY) > 1) {
      logo.x += distX * 0.1;
      logo.y += distY * 0.1;
    }
  }

  new Phaser.Game(config);
</script>
</body>
</html>

🎮 What This Code Does

Scene Lifecycle: You now use all three Phaser lifecycle functions: preload(), create(), and update().
Input Handling: pointerdown listens for taps/touches on the screen.
Smooth Movement: The update() function animates the logo smoothly toward the tapped position.

📱 Step 2: Run the App in React Native

No changes are needed in App.js. Just run:

expo start

Scan with Expo Go or run on an emulator. Tap anywhere on the screen and the Phaser logo will animate smoothly to that point.

🧩 Bonus: Use Physics for Movement (Optional)

Want to try physics-based motion? Replace the movement logic in create() and update() with:

this.physics.add.existing(logo);
logo.body.setVelocity(0);

this.input.on('pointerdown', function (pointer) {
  const angle = Phaser.Math.Angle.Between(logo.x, logo.y, pointer.x, pointer.y);
  this.physics.moveTo(logo, pointer.x, pointer.y, 200);
}, this);

And add physics to your config:

physics: { default: 'arcade' }

✅ What You’ve Achieved

Created a game loop using update()
Handled user input (tap/touch)
Moved a sprite smoothly across the screen
Laid the foundation for player controls and interactive gameplay

📌 Up Next

In Day 3, we’ll build game objects like enemies and collectibles, and implement collision detection to trigger in-game events.

You’re now officially building your mobile game logic — one step closer to publishing!

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