將多個蒙版分配給SKCropNode

Question

作爲一個例子，我有一個圓圈向左移動，然後在屏幕上向右移動。我希望圓只有在兩個特定方塊（maskNodes）內時纔可見。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。有沒有人知道給SKCropNode分配兩個或多個掩碼的方法，或者甚至可以這樣做。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

想出來，只需將兩個掩碼添加到父項，然後將父項指定爲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) 

}