使用 Swift 和 Sprite-Kit,我正在尝试在称为“pin”的静态 SKSpriteNode 的位置和用户触摸屏幕的任何位置之间创建具有真实物理特性的绳索。我通过添加称为ropeNodes 的单个SKSpriteNodes 来做到这一点,并将它们与一系列SKPhysicsJointPins 链接起来。物理效果很好,但是当我尝试旋转每个单独的部分以使其正确定向时,ropeNodes 不再形成直线,它们也不会旋转到正确的角度。但是,当我删除 SKPhysicsJoints 时,旋转按每个单独节点的预期工作。为每个单独的ropeNode 移动anchorPoint 似乎只会让事情变得更糟。为什么会发生这种情况,我该如何解决?提前致谢 (:
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
/* Called when a touch begins */
for touch in (touches as! Set<UITouch>) {
let location = touch.locationInNode(self)
dx = pin.position.x - location.x
dy = pin.position.y - location.y
let length = sqrt(pow(dx!, 2) + pow(dy!, 2))
let distanceBetweenRopeNodes = 40
let numberOfPieces = Int(length)/distanceBetweenRopeNodes
var ropeNodes = [SKSpriteNode]()
//adds the pieces to the array and the scene at respective locations
for var index = 0; index < numberOfPieces; ++index{
let point = CGPoint(x: pin.position.x + CGFloat((index) * distanceBetweenRopeNodes) * sin(atan2(dy!, -dx!) + 1.5707), y: pin.position.y + CGFloat((index) * distanceBetweenRopeNodes) * cos(atan2(dy!, -dx!) + 1.5707))
let piece = createRopeNode(point)
piece.runAction(SKAction.rotateByAngle(atan2(-dx!, dy!), duration: 0))
ropeNodes.append(piece)
self.addChild(ropeNodes[index])
}
//Adds an SKPhysicsJointPin between each pair of ropeNodes
self.physicsWorld.addJoint(SKPhysicsJointPin.jointWithBodyA(ropeNodes[0].physicsBody, bodyB: pin.physicsBody, anchor:
CGPoint(x: (ropeNodes[0].position.x + pin.position.x)/2, y: (ropeNodes[0].position.y + pin.position.y)/2)))
for var i = 1; i < ropeNodes.count; ++i{
let nodeA = ropeNodes[i - 1]
let nodeB = ropeNodes[i]
let middlePoint = CGPoint(x: (nodeA.position.x + nodeB.position.x)/2, y: (nodeA.position.y + nodeB.position.y)/2)
let joint = SKPhysicsJointPin.jointWithBodyA(nodeA.physicsBody, bodyB: nodeB.physicsBody, anchor: middlePoint)
self.physicsWorld.addJoint(joint)
}
}
}
func createRopeNode(location: CGPoint) -> SKSpriteNode{
let ropeNode = SKSpriteNode(imageNamed: "RopeTexture")
ropeNode.physicsBody = SKPhysicsBody(rectangleOfSize: ropeNode.size)
ropeNode.physicsBody?.affectedByGravity = false
ropeNode.physicsBody?.collisionBitMask = 0
ropeNode.position = location
ropeNode.name = "RopePiece"
return ropeNode
}
这是我尝试旋转每个单独的ropeNode 时发生的情况的图像