2个动态物理对象如何相互接触而不会相互影响？

Question

我希望我的背景充满活力。但我在背景中奔跑的英雄也是动态的。当我移动他时，他也会影响我的背景。

2个动态对象可以相互重叠而不会影响彼此的物理吗？

如果是这样，怎么样？

我尝试给他们不同的categoryBitMasks，但他们仍然相互影响。

iOS和编程一般来说还是一个新手。

这是代码

override func didMoveToView(view: SKView) {





    background.anchorPoint = CGPoint(x: 0, y: 0)
   // background.color = UIColor(red: 0, green: 0, blue: 0, alpha: 1)
    background.size = CGSize(width: size.width, height: size.height)
    background.name = "bg"
    background.position = CGPoint(x: 0, y: 0)
    background.physicsBody = SKPhysicsBody(rectangleOfSize: background.size)
    background.physicsBody?.dynamic = true

    background.physicsBody?.categoryBitMask = bgCategory // 3
    background.physicsBody?.contactTestBitMask = bgCategory
    background.physicsBody?.collisionBitMask = noneCategory
    addChild(background)


    background2.anchorPoint = CGPoint(x: 0, y:0)
    background2.size = CGSize(width: size.width, height: size.height)
    background2.position = CGPoint(x: size.width, y: 0)
    background2.physicsBody = SKPhysicsBody(rectangleOfSize: background2.size)
    background2.physicsBody?.dynamic = true

    background2.physicsBody?.categoryBitMask = bgCategory // 3
    background2.physicsBody?.contactTestBitMask = bgCategory
    background2.physicsBody?.collisionBitMask = noneCategory


    addChild(background2)











    scoreLabel.position = CGPoint(x: size.width * 0.5, y: size.height * 0.9)
    scoreLabel.text = "\(score)"
    addChild(scoreLabel)



    physicsWorld.gravity = CGVectorMake(0, 0)
    physicsWorld.contactDelegate = self


   let boPhysicsSize = CGSizeMake(boWidth - boWidth/2, boHeight - boHeight/6)
    bo.physicsBody = SKPhysicsBody(rectangleOfSize: boPhysicsSize)
    bo.position = CGPoint(x: -(bo.size.width), y: size.height * 0.5)
    bo.physicsBody?.dynamic = true
    bo.physicsBody?.categoryBitMask = boCategory // 3
    bo.physicsBody?.contactTestBitMask = chainsawCategory // 4

    addChild(bo)


func rightImpulse () {
    bo.physicsBody?.applyImpulse(CGVector(bo.size.width/40, 0))
    background.physicsBody?.applyImpulse(CGVector(-(bo.size.width/40*100), 0))
    background2.physicsBody?.applyImpulse(CGVector(-(bo.size.width/40*100), 0))


}
func leftImpulse () {
    bo.physicsBody?.applyImpulse(CGVector(-(bo.size.width/40), 0))
    background.physicsBody?.applyImpulse(CGVectorMake(bo.size.width/40*100, 0))
    background2.physicsBody?.applyImpulse(CGVectorMake(bo.size.width/40*100, 0))

}
func upImpulse () {
    bo.physicsBody?.applyImpulse(CGVector(0, bo.size.width/40))


}
func downImpulse () {
    bo.physicsBody?.applyImpulse(CGVector(0, -(bo.size.width/40)))

}