ios - 如何将粒子附加到移动的物体上

Question

我创建了一个 PowerUpTrail.sks(粒子之物)我正在尝试将其附加到移动的物体上

func SpawnPowerUp(){

    let PowerUp = SKSpriteNode(imageNamed: "PowerUp.png")
    let MinValue = self.size.width / 8
    let MaxValue = self.size.width - 20
    let SpawnPoint = UInt32(MaxValue - MinValue)
    PowerUp.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.size.height - 100)

    //Physics
    PowerUp.physicsBody = SKPhysicsBody(rectangleOfSize: PowerUp.size)
    PowerUp.physicsBody?.categoryBitMask = PhysicsCategory.PowerUp //Sätter unikt ID för Enemy, hämtat från PhysicsCategory som vi gjorde där uppe
    PowerUp.physicsBody?.contactTestBitMask = PhysicsCategory.PowerUp //Kolla om Enemy nuddar Bullet
    PowerUp.physicsBody?.affectedByGravity = false
    PowerUp.physicsBody?.dynamic = true

    let action = SKAction.moveToY(-128, duration: 5)
    let actionDone = SKAction.removeFromParent()
    PowerUp.runAction(SKAction.sequence([action, actionDone]))
    PowerUp.runAction(SKAction.rotateByAngle(5, duration: 5))


    /* this does not work!
    let PowerUpTrail = SKEmitterNode(fileNamed: "PowerUpTrail.sks")
    PowerUpTrail!.targetNode = self
    PowerUpTrail!.position = PowerUp.position
    self.addChild(PowerUpTrail!)
    */

    self.addChild(PowerUp)

}

粒子事物产生，但它不跟随该物体。我该如何解决这个问题？

Answer 1

使一个节点的位置跟踪另一个节点的最简单方法是使用节点层次结构:使粒子发射器成为通电 Sprite 的子节点。

let powerUp = SKSpriteNode(imageNamed: "PowerUp.png")
// ...
let powerUpTrail = SKEmitterNode(fileNamed: "PowerUpTrail.sks")!
powerUpTrail.targetNode = self
powerUp.addChild(powerUpTrail)

(另请注意一些 Swift 风格提示:initial-cap 通常仅用于类型名称；使用 initial-lowercase 用于变量名称。并在创建时从 SKEmitterNode(fileNamed:) 解包一次它而不是每次你之后使用它。)