phaser-arcade-physics Checked

create() {
  this.player = this.physics.add.sprite(400, 300, 'player');
  this.player.setCollideWorldBounds(true);
  this.cursors = this.input.keyboard.createCursorKeys();
}

update() {
  const speed = 220;
  const body = this.player.body;
  body.setVelocity(0);                              // reset each frame
  if (this.cursors.left.isDown)  body.setVelocityX(-speed);
  if (this.cursors.right.isDown) body.setVelocityX(speed);
  if (this.cursors.up.isDown)    body.setVelocityY(-speed);
  if (this.cursors.down.isDown)  body.setVelocityY(speed);
  body.velocity.normalize().scale(speed);           // keep diagonals same speed
}

### 3. Platformer jump (gravity + ground check)

create() {
  this.player = this.physics.add.sprite(100, 450, 'player');
  this.player.setCollideWorldBounds(true);

  // Static platforms: one body each, never moved by collisions.
  this.platforms = this.physics.add.staticGroup();
  this.platforms.create(400, 568, 'ground');
  this.physics.add.collider(this.player, this.platforms);

  this.cursors = this.input.keyboard.createCursorKeys();
}

update() {
  const onGround = this.player.body.blocked.down; // or this.player.body.onFloor()
  if (this.cursors.left.isDown)  this.player.setVelocityX(-160);
  else if (this.cursors.right.isDown) this.player.setVelocityX(160);
  else this.player.setVelocityX(0);

  if (this.cursors.up.isDown && onGround) this.player.setVelocityY(-450);
}

### 4. Colliders vs overlaps (separate vs detect)

// Push apart and react: player vs enemies.
this.physics.add.collider(this.player, this.enemies, (player, enemy) => {
  this.handleHit(player, enemy);
});

// Detect without pushing: collect coins. The 4th arg is an optional
// process callback returning a boolean to filter pairs before the main callback.
this.physics.add.overlap(this.player, this.coins, (player, coin) => {
  coin.disableBody(true, true);              // deactivate + hide
  this.registry.inc('score', 10);
});

### 5. A group of moving objects

this.bullets = this.physics.add.group({
  defaultKey: 'bullet',
  maxSize: 30                  // pool size; reuse instead of allocating
});

fire(x, y) {
  const bullet = this.bullets.get(x, y);     // reuses a dead bullet if available
  if (!bullet) return;
  bullet.enableBody(true, x, y, true, true);
  bullet.setVelocityY(-500);
}

Pitfalls

• **Sprite ignores physics** → it was added with this.add.sprite instead of

this.physics.add.sprite (or this.physics.add.existing(obj)), so it has no body.

• **Setting sprite.x directly fights the engine** → move dynamic bodies with

setVelocity/setAcceleration. Direct position writes can tunnel through colliders.

• **Diagonal movement is faster** → independent X and Y velocities add up; normalise

the velocity vector and rescale to the intended speed.

• **Platforms get pushed by the player** → use a staticGroup, or set

body.setImmovable(true) on a dynamic platform.

• **onFloor() is always false** → the body needs something to collide with; add the

collider against the ground/platforms before checking, and ensure gravity is on.

• **Moved a static body but collisions are stale** → static bodies don't auto-sync;

call body.updateFromGameObject() (or refreshBody() on the game object).

• **Collider added every frame** → register collider/overlap once in create,

not in update.

References

• For body anatomy and tuning (drag, bounce, max velocity, custom setSize/

setCircle/setOffset hitboxes, collision categories/masks, and worldbounds

events), read references/bodies-and-collision.md.

Related skills

• phaser-core — game config, scenes, loader, cameras (the prerequisite setup).
• physics-tuning — engine-agnostic feel (fixed timestep, tunneling, jitter).
• platformer / tower-defense — genres that compose this skill.
• level-design — laying out tile/platform geometry these bodies collide with.