Javascript Phaser：将精灵旋转改变为其运动方向

document.body.style = 'margin:0;';

var config = {
    type: Phaser.AUTO,
    width: 536,
    height: 183,
    physics: {
        default: 'arcade',
        arcade: {            
            gravity: { y: 0 },
        }
    },
    scene: { create }
}; 

function create () {
    this.add.text(10,10, 'DEMO TEXT')
        .setScale(1.5)
        .setOrigin(0)
        .setStyle({fontStyle: 'bold', fontFamily: 'Arial'});

    let graphics  = this.make.graphics();
    graphics.fillStyle(0xffffff);
    graphics.fillTriangle(0, 0, 10, 5, 0, 10);
    graphics.generateTexture('img', 10, 10);
    
    this.photons = this.physics.add.group({
      key: "img",
      repeat: 2,
      setXY: { x: 50, y: 50, stepX: 32 },
    });

    this.photons.children.iterate(function (child) {
      child.body.bounce.set(1);
      child.setVelocity(Phaser.Math.Between(0, 100),30);
      let initialAngle = (new Phaser.Math.Vector2(child.body.velocity)).angle();
      child.setRotation(initialAngle);
      child.body.collideWorldBounds = true;
      child.body.onWorldBounds = true;
    });
    
    this.physics.world.on('worldbounds', (photon) => {
        let newAngle = (new Phaser.Math.Vector2(photon.velocity)).angle();
        photon.gameObject.setRotation(newAngle);
    });
    
    this.physics.add.collider(this.photons, this.photons, (p1, p2) => {
        let newAngle = (new Phaser.Math.Vector2(p1.body.velocity)).angle();
        p1.setRotation(newAngle);
        newAngle = (new Phaser.Math.Vector2(p2.body.velocity)).angle();
        p2.setRotation(newAngle);
    });
}

new Phaser.Game(config);

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