Swift SpriteKit 重力点

Question

我需要在 Swift 中制作类似 Gravity Point 的东西。 SpriteNode 位于屏幕中间，通过左右手势可以沿 x 轴移动。

但是在例如之后'RightSwipe'，它应该回到他的起点。你可以说它应该看起来像沿 x 轴的跳跃。

世界重力不可能是一个特定的点，那我怎么能“强迫”它回到原来的点呢？

我用 SKFieldNode 的 RadialGravityField 试过了，但是在 Nodes 脉冲产生之后，它又回到了他的原点并消失了。 我怎样才能避免这种情况？

我的代码：

{ 
.......

Node = SKSpriteNode(texture: Node1)
Node.size = CGSize(width: 100, height: 140)
Node.position = CGPoint(x: self.frame.size.width / 2, y: self.frame.size.height / 4)
Node.zPosition = 3
Node.runAction(RunAnimation)

Node.physicsBody = SKPhysicsBody(rectangleOfSize: Node.size)
Node.physicsBody?.dynamic = true
Node.physicsBody?.allowsRotation = false
Node.physicsBody?.usesPreciseCollisionDetection = true
Node.physicsBody?.restitution = 0
Node.physicsBody?.velocity = CGVectorMake(0, 0)

self.addChild(Node)

let swipeRight:UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: Selector("SwipeRight:"))
swipeRight.direction = .Right
view.addGestureRecognizer(swipeRight)


let swipeLeft:UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: Selector("SwipeLeft:"))
swipeLeft.direction = .Left
view.addGestureRecognizer(swipeLeft)

}

func SwipeRight(recognizer:UISwipeGestureRecognizer) {

Node.physicsBody?.applyImpulse(CGVectorMake(10,0))

}

func SwipeLeft(recognizer:UISwipeGestureRecognizer) {

Node.physicsBody?.applyImpulse(CGVectorMake(-10,0))

}

override func update(currentTime: CFTimeInterval) {

if(Node.position.x > self.frame.size.width / 1.6)
    {
        fieldNode = SKFieldNode.radialGravityField()
        fieldNode.enabled = true
        fieldNode.position = CGPoint(x: self.frame.size.width / 2, y: self.frame.size.height / 4)
        fieldNode.strength = 0.4
        addChild(fieldNode)
    }

    if(Node.position.x < self.frame.size.width / 2.6)
    {
        fieldNode = SKFieldNode.radialGravityField()
        fieldNode.enabled = true
        fieldNode.position = CGPoint(x: self.frame.size.width / 2, y: self.frame.size.height / 4)
        fieldNode.strength = 0.4
        addChild(fieldNode)
    }

Answer 1

听起来像是径向重力SKFieldNode 的工作。 link