為 SKCropNode 分配多個掩碼

Question

例如，我有一個圓圈，它在屏幕上向左移動，然后向右移動。 我希望圓圈只有在兩個特定方塊（maskNodes）內時才可見。 我正在使用 SKCropNode 來嘗試實現這一點，但 SKCropNode 掩碼只允許我分配一個掩碼。 有沒有人知道一種將兩個或多個掩碼分配給 SKCropNode 的方法，或者是否有可能這樣做。 謝謝！

override func didMoveToView(view: SKView) {

    anchorPoint = CGPointMake(0.5, 0.5)
    backgroundColor = UIColor.whiteColor()

    let mask1 = SKSpriteNode(color: UIColor.blackColor(), size: CGSizeMake(50, 50))
    mask1.position.x = -100

    let mask2 = SKSpriteNode(color: UIColor.blackColor(), size: CGSizeMake(50, 50))
    mask2.position.x = 100

    let cropNode = SKCropNode()
    cropNode.maskNode = mask1 // && mask2
    addChild(cropNode)

    let circle = SKShapeNode(circleOfRadius: 25)
    circle.fillColor = UIColor.blackColor()
    cropNode.addChild(circle)


    // Move Circle

    let moveLeft = SKAction.moveToX(-frame.size.width/2, duration: 2)
    let moveRight = SKAction.moveToX(frame.size.width/2, duration: 2)
    let seq = SKAction.repeatActionForever(SKAction.sequence([moveLeft, moveRight]))

    circle.runAction(seq)

}

Answer 1

想通了，只需要將兩個掩碼添加到父級，然后將父級分配為 SKCropNode 掩碼。

override func didMoveToView(view: SKView) {

    anchorPoint = CGPointMake(0.5, 0.5)
    backgroundColor = UIColor.whiteColor()

    let maskParent = SKSpriteNode()

    let mask1 = SKSpriteNode(color: UIColor.blackColor(), size: CGSizeMake(50, 50))
    mask1.position.x = -100
    maskParent.addChild(mask1)

    let mask2 = SKSpriteNode(color: UIColor.blackColor(), size: CGSizeMake(50, 50))
    mask2.position.x = 100
    maskParent.addChild(mask2)

    let cropNode = SKCropNode()
    cropNode.maskNode = maskParent

    addChild(cropNode)

    let circle = SKShapeNode(circleOfRadius: 25)
    circle.fillColor = UIColor.blackColor()
    cropNode.addChild(circle)

    // Move Circle

    let moveLeft = SKAction.moveToX(-frame.size.width/2, duration: 2)
    let moveRight = SKAction.moveToX(frame.size.width/2, duration: 2)
    let seq = SKAction.repeatActionForever(SKAction.sequence([moveLeft, moveRight]))

    circle.runAction(seq)

}