如何使用SKPhysicsJointPin连接两个SKSpriteNode - swift

Question

我试图连接两个SKSpriteNode使用的SKPhysicsJointPin在anchorPoint标记为下面的截图绿点.后来我想physicsBody!.dynamic = true在object2上启用object2的"swing动画".

我在创建偶像时遇到困难SKPhysicsJointPin我甚至没有在Xcode中得到错误它不能编译.

这是代码:

import SpriteKit

class GameScene: SKScene, SKPhysicsContactDelegate {

let object1 = SKSpriteNode(imageNamed: "white")
let object2 = SKSpriteNode(imageNamed: "black")

override func didMoveToView(view: SKView) {
    // Setup background image
    self.backgroundColor = UIColor(hex: 0x60c0f3)

    // Setup physics body to the scene (borders)
    self.physicsBody = SKPhysicsBody (edgeLoopFromRect: self.frame)

    // Change gravity settings of the physics world
    self.physicsWorld.gravity = CGVectorMake(0, -9.8)
    self.physicsWorld.contactDelegate = self

    //===========================================

    // White object properties
    object1.physicsBody = SKPhysicsBody(rectangleOfSize: object1.frame.size)
    object1.physicsBody!.dynamic = false
    object1.position = CGPointMake(size.width/2 - object1.size.width/2, size.height/2)

    // Black object properties
    object2.physicsBody = SKPhysicsBody(rectangleOfSize: object2.frame.size)
    object2.physicsBody!.dynamic = true
    object1.anchorPoint = CGPointMake(0, 0)
    object2.position = CGPointMake(size.width/2 + object2.size.width + 2, size.height/2 + object2.size.height/2)

    // Create joint between two objects
    var myJoint = SKPhysicsJointPin.jointWithBodyA(object1.physicsBody, bodyB: object2.physicsBody, anchor: CGPoint(x: CGRectGetMaxX(self.object1.frame), y: CGRectGetMaxY(self.object2.frame)))

    self.physicsWorld.addJoint(myJoint)
    self.addChild(object1)
    self.addChild(object2)

}

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */
}
}

我得到的Xcode错误是

请告知我的代码有什么问题.谢谢.

Answer 1

两个问题：1）您需要将包含物理体的节点添加到场景中，然后再使用关节连接它们；2）您需要以最小 Y 值而不是最大值连接节点（如果您希望关节表现良好）如图所示），因为场景的原点是视图的左下角，并且正 Y 向上。

    // Do this prior to adding the joint to the world
    self.addChild(object1)
    self.addChild(object2)

    // Create joint between two objects. Edit: changed MaxY to MinY to attach bodies 
    // at bottom of the nodes
    var myJoint = SKPhysicsJointPin.jointWithBodyA(object1.physicsBody, bodyB: object2.physicsBody, anchor: CGPoint(x: CGRectGetMaxX(self.object1.frame), y: CGRectGetMinY(self.object2.frame)))

    self.physicsWorld.addJoint(myJoint)