如何围绕关节旋转精灵 [英] How to rotate sprites around a joint

问题描述

我需要让手臂和手围绕钩子的中心旋转，如下图所示，没有它们分开或改变它们的形状(手臂和手之间的角度没有变化，只是在 A 处旋转)，如下图:

I need to make the arms and hands rotate around the center of the hook, as shown in the image below without them separating or changing their shape (no changes in the angles between arms and hands just rotation at A), as in the image below:

我尝试旋转手臂，但这使它们分开并改变形状.您可以在下面查看我的代码:

I tried rotating the arms but this made them separate and change form. You can check out my code below:

let hookCategoryName = "hook"
let leftArmCategoryName = "leftArm"
let rightArmCategoryName = "rightArm"
let leftHandCategoryName = "leftHand"
let rightHandCategoryName = "rightHand"

let hookCategory             : UInt32 = 0x1 << 0
let leftArmCategory            : UInt32 = 0x1 << 1
let rightArmCategory           : UInt32 = 0x1 << 2
let leftHandCategory           : UInt32 = 0x1 << 3
let rightHandCategory          : UInt32 = 0x1 << 4

extension Int {
  var degreesToRadians: Double { return Double(self) * .pi / 180 }
}
extension FloatingPoint {
  var degreesToRadians: Self { return self * .pi / 180 }
  var radiansToDegrees: Self { return self * 180 / .pi }
}

class GameScene: SKScene, SKPhysicsContactDelegate {

var hook = SKSpriteNode(imageNamed: "hook")
var leftArm = SKSpriteNode(imageNamed: "arm")
var rightArm = SKSpriteNode(imageNamed: "arm")
var leftHand = SKSpriteNode(imageNamed: "leftHand")
var rightHand = SKSpriteNode(imageNamed: "rightHand")

override func didMove(to view: SKView) {

    self.physicsWorld.gravity = CGVector(dx: 0, dy: 0)
    self.physicsWorld.contactDelegate = self

    var yellowBg = SKSpriteNode(imageNamed: "yellowBg")
    yellowBg.position = CGPoint(x: frame.midX, y: frame.midY)
    yellowBg.zPosition = 2
    addChild(yellowBg)

    hook.position = CGPoint(x: frame.midX, y: frame.midY + frame.midY/2)
    hook.zPosition = 5
    hook.name = hookCategoryName
    hook.physicsBody = SKPhysicsBody(rectangleOf: hook.frame.size)
    hook.physicsBody?.categoryBitMask = hookCategory
    hook.physicsBody?.isDynamic = false
    addChild(hook)

    rightArm.anchorPoint = CGPoint(x: 0.5, y: 1)
    rightArm.position = hook.position
    rightArm.zPosition = 5
    rightArm.name = rightArmCategoryName
    rightArm.physicsBody = SKPhysicsBody(rectangleOf: rightArm.frame.size)
    rightArm.physicsBody?.categoryBitMask = rightArmCategory

    rightArm.physicsBody!.isDynamic = true
    addChild(rightArm)

    leftArm.anchorPoint = CGPoint(x: 0.5, y: 1)
    leftArm.position = hook.position
    leftArm.zPosition = 5
    leftArm.name = leftArmCategoryName
    leftArm.physicsBody = SKPhysicsBody(rectangleOf: leftArm.frame.size)
    leftArm.physicsBody?.categoryBitMask = leftArmCategory
    leftArm.physicsBody!.isDynamic = true

    addChild(leftArm)

    // leftHand
    leftHand.anchorPoint = CGPoint(x: 0.5, y: 0.5)
    leftHand.position = CGPoint(x: leftArm.frame.minX - 22, y: leftArm.frame.minY + 7) //CGPoint(x: armLeft.position.x, y: armLeft.position.y)
    leftHand.zPosition = 5
    leftHand.name = leftHandCategoryName
    leftHand.physicsBody = SKPhysicsBody(rectangleOf: leftHand.frame.size)
    leftHand.physicsBody?.categoryBitMask = leftHandCategory

    leftHand.zRotation = CGFloat(Double(-30).degreesToRadians)//CGFloat(-Double.pi/6)
    //armLeft.physicsBody?.categoryBitMask = armCategory
    leftHand.physicsBody!.isDynamic = true

    addChild(leftHand)

    // rightHand
    rightHand.anchorPoint = CGPoint(x: 0.5, y: 0.5)
    rightHand.position = CGPoint(x: rightArm.frame.minX + 30, y: rightArm.frame.minY + 7) //CGPoint(x: armLeft.position.x, y: armLeft.position.y)
    rightHand.zPosition = 5
    rightHand.name = rightHandCategoryName

    rightHand.physicsBody = SKPhysicsBody(rectangleOf: rightHand.frame.size)
    rightHand.physicsBody?.categoryBitMask = rightHandCategory
    rightHand.zRotation = CGFloat(Double(30).degreesToRadians)//CGFloat(-Double.pi/6)
    //armLeft.physicsBody?.categoryBitMask = armCategory
    rightHand.physicsBody!.isDynamic = true

    addChild(rightHand)


    leftArm.zRotation = CGFloat(Double(-45).degreesToRadians)
    rightArm.zRotation = CGFloat(Double(45).degreesToRadians)

    rightHand.physicsBody?.contactTestBitMask = rightHandCategory
    leftHand.physicsBody?.contactTestBitMask = leftHandCategory
    rightHand.physicsBody?.collisionBitMask = rightHandCategory
    leftHand.physicsBody?.collisionBitMask = leftHandCategory


    let hookAndRightArmJoint = SKPhysicsJointPin.joint(withBodyA: hook.physicsBody!, bodyB: rightArm.physicsBody!, anchor: CGPoint(x: hook.position.x, y: self.rightArm.frame.maxY))
    self.physicsWorld.add(hookAndRightArmJoint)

    let hookAndLeftArmJoint = SKPhysicsJointPin.joint(withBodyA: hook.physicsBody!, bodyB: leftArm.physicsBody!, anchor: CGPoint(x: hook.position.x, y: self.leftArm.frame.maxY))
    self.physicsWorld.add(hookAndLeftArmJoint)


    let armsFixedJoint = SKPhysicsJointFixed.joint(withBodyA: leftArm.physicsBody!, bodyB: rightArm.physicsBody!, anchor: CGPoint.zero)
    self.physicsWorld.add(armsFixedJoint)

    //left arm and hand joint
    let leftArmAndHandJoint = SKPhysicsJointPin.joint(withBodyA: leftArm.physicsBody!, bodyB: leftHand.physicsBody!, anchor: CGPoint(x: self.leftArm.frame.minX, y: self.leftArm.frame.minY)/*CGPoint(x: armLeft.position.x, y: self.armLeft.frame.minY)*/)
    self.physicsWorld.add(leftArmAndHandJoint)

    //right arm and hand joint
    let rightArmAndHandJoint = SKPhysicsJointPin.joint(withBodyA: rightArm.physicsBody!, bodyB: rightHand.physicsBody!, anchor: CGPoint(x: self.rightArm.frame.maxX, y: self.rightArm.frame.minY)/*CGPoint(x: armLeft.position.x, y: self.armLeft.frame.minY)*/)
    self.physicsWorld.add(rightArmAndHandJoint)
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

    hook.run(SKAction.rotate(byAngle: CGFloat(Double(60).degreesToRadians), duration: 0.5))

}
}  

当上面的代码运行时，同样旋转钩子对手臂和手没有影响，如下图所示:

Also rotating the hook has no effect on the arms and hands as seen in the image below when the above code is run:

如何在图像第一张图像中获得旋转?

How can I get the rotation in the image first image?

推荐答案

您可以将手臂和手设为公共父节点的子节点.您可以为此目的创建一个空白的 SKNode，如下所示:

You can make the arms and hands children of a common parent node. You could create a blank SKNode for just this purpose like so:

let armsParent = SKNode()

然后不是将手臂和手作为孩子直接添加到场景中，而是将它们添加为armParent的孩子，如下所示:

Then instead of adding the arms and hands as children to the scene directly, add them as children of armsParent like so:

armsParent.addChild(leftArm)
armsParent.addChild(rightArm) // same for hands...

然后您可以简单地使用 SKAction 旋转 armParent 来实现您想要的.

Then you can simply rotate armsParent with an SKAction to achieve what you want.

或者，为了更简单，你可以像这样直接将手臂和手作为孩子添加到hook:

OR, to make it even simpler, you could just add the arms and hands as children to hook directly like this:

hook.addChild(leftArm) // same for other arm and hands...

由于手臂和手是 hook 或 armParent 的孩子，它们的位置现在将相对于它们的父母确定.因此，您可能需要更改所有 .position = 初始化代码以适应这一点.

Since the arms and hands are children of hook or armParent their positions will now be determined relative to their parent. So you might have to change all your .position = initialization code to accommodate this.

这篇关于如何围绕关节旋转精灵的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！