How to rotate sprite in sprite kit with swift

Question

Hi my problem is regarding the rotation of two sprites. When I touch the right half of the screen the rotation starts and moving sprite2 and sprite3. If I touch the left half of the screen the rotation stops because velocity-velocity = 0. If I touch the left half again the rotation begins.

However, if I touch the half of the screen corresponding with the current rotational-direction the velocity is duplicated. I want to be able to change the direction of the rotation, but for the speed to remain constant.

Video demonstrating the problem: http://youtu.be/HxLwl1QZiNM

import SpriteKit

class GameScene: SKScene {
    let sprite = SKSpriteNode(imageNamed:"bWhite")
    let sprite2 = SKSpriteNode(imageNamed:"bBlue")
    let sprite3 = SKSpriteNode(imageNamed:"bRed")
    let circle = SKSpriteNode(imageNamed:"bCircle")       

    override func didMoveToView(view: SKView) {
        /* Setup your scene here */
        backColor = SKColor(red: 0, green: 0, blue: 0, alpha: 1)
        self.backgroundColor = backColor

        sprite.setScale(1.25)
        sprite2.setScale(1)
        sprite3.setScale(1)
        sprite.position = CGPointMake(self.frame.size.width/2, (self.frame.size.height/2)-200);
        circle.position = CGPointMake(self.frame.size.width/2, (self.frame.size.height/2)-200);
        sprite3.zRotation = 172.77
        sprite2.anchorPoint = CGPointMake(-1.10, 0.5);
        sprite3.anchorPoint = CGPointMake(-1.10, 0.5);

        self.addChild(sprite)
        self.addChild(circle)
        sprite.addChild(sprite2)
        sprite.addChild(sprite3)
    }

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        /* Called when a touch begins */
        for touch: AnyObject in touches {
            let location = touch.locationInNode(self)

            let action = SKAction.rotateByAngle(CGFloat(M_PI), duration:1)
            let action2 = SKAction.rotateByAngle(CGFloat(-M_PI), duration:1)

            if (location.x > self.frame.size.width / 2)
            {
                sprite2.runAction(SKAction.repeatActionForever(action2))
                sprite3.runAction(SKAction.repeatActionForever(action2))
            } else {
                sprite2.runAction(SKAction.repeatActionForever(action))
                sprite3.runAction(SKAction.repeatActionForever(action))
            }     
        }
    }

Answer 1

I suggest removing all current actions before adding new, since they may conflict. I'm still not sure what you are trying to achieve, can you explain more?

Answer 2

Have you just tired removing the actions at touchesEnded? I had a similar problem before where I wanted my object to move left to right based on which half of the screen the user touched. I had a similar issue where if I touched right and right again my velocity would double, and if I touched left my object would just stop.

I fixed this issue by adding the touchesEnded method and just removed the actions whenever I let go. This essentially reset my move action so the object would stop when I let go and would go to the opposite direction right away instead of having to tap it twice.

Answer 3

OK, take three. I'm not 100% sure about the specifics of when the rotation should end etc. but all the pieces should be in place with the below code. It will:

• start rotation clockwise or counterclockwise based on the position of the first touch
• stop the rotation if the user touches for the same direction again

• switch the rotation if the user touches on the other half of the screen

    import SpriteKit  
  
    enum rotationDirection{
         case clockwise
         case counterClockwise
         case none
     } 
  
    class GameScene: SKScene {
      var currentRotationDirection = rotationDirection.none
      let sprite = SKSpriteNode(color: UIColor.yellowColor(), size: CGSizeMake(100, 100))
  
      override func didMoveToView(view: SKView) {
        sprite.physicsBody = SKPhysicsBody(rectangleOfSize: sprite.size)
        sprite.physicsBody.affectedByGravity = false
        sprite.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
        self.addChild(sprite)
      }
  
      override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        let touch : UITouch = touches.anyObject() as UITouch
        let touchPosition = touch.locationInNode(self)
        let newRotationDirection : rotationDirection = touchPosition.x < CGRectGetMidX(self.frame) ? .clockwise : .counterClockwise
  
        if currentRotationDirection != newRotationDirection && currentRotationDirection != .none{
          reverseRotation()
          currentRotationDirection = newRotationDirection
        } else if currentRotationDirection == newRotationDirection{
          stopRotation()
          currentRotationDirection = .none
        } else if (currentRotationDirection == .none){
        setupRotationWith(direction: newRotationDirection)
        currentRotationDirection = newRotationDirection
        }
      }
  
      func reverseRotation(){
        let oldRotateAction = sprite.actionForKey("rotate")
        let newRotateAction = SKAction.reversedAction(oldRotateAction)
        sprite.runAction(newRotateAction(), withKey: "rotate")
      }
  
      func stopRotation(){
        sprite.removeActionForKey("rotate")
      }
  
      func setupRotationWith(#direction: rotationDirection){
        let angle : Float = (direction == .clockwise) ? Float(M_PI) : -Float(M_PI)
        let rotate = SKAction.rotateByAngle(angle, duration: 1)
        let repeatAction = SKAction.repeatActionForever(rotate)
        sprite.runAction(repeatAction, withKey: "rotate")
      }
    }
  

---

Edit: Changed example to cater the specific needs in the question. Something odd with the code formatting not quite sure what's going on there.