如何CGPath或SKShapeNode旋轉

Question

我想添加旋轉的橢圓路徑到一箇中心點。像下面的圖像，但隨機旋轉橢圓。

繪製這些橢圓軌道，

roadShape = SKShapeNode(ellipseInRect: centeredRect) 
roadShape.strokeColor = UIColor.greenColor() 
self.parent!.addChild(roadShape) 

需要使小顆粒遵循這​​些橢圓軌道，這就是爲什麼我需要一個路徑。

var followPath = SKAction.followPath(roadShape.path, asOffset: false, orientToPath: true, duration: 10); 
particle.runAction(followPath) 

我用SKShapeNode繪製並獲取路徑屬性。但不幸的是SKShapeNode沒有任何origin或anchorPoint屬性，所以我不能像樣的旋轉到SKShapeNode。你有任何建議讓它旋轉或不同的方式。

在此先感謝。

Answer 1

let roadShape1 = SKShapeNode(ellipseInRect: CGRectMake(-100, -25, 200, 50)) 
roadShape1.strokeColor = UIColor.greenColor() 
roadShape1.lineWidth = 3 
roadShape1.position = CGPoint(x:frame.midX, y: frame.midY) 
addChild(roadShape1) 


let roadShape2 = SKShapeNode(ellipseInRect: CGRectMake(-100, -25, 200, 50)) 
roadShape2.strokeColor = UIColor.greenColor() 
roadShape2.lineWidth = 3 

let action2 = SKAction.rotateByAngle(CGFloat(M_PI)*0.75, duration:0) 
roadShape2.runAction(action2) 
roadShape2.position = CGPoint(x:frame.midX, y: frame.midY) 
addChild(roadShape2) 


let roadShape3 = SKShapeNode(ellipseInRect: CGRectMake(-100, -25, 200, 50)) 
roadShape3.strokeColor = UIColor.greenColor() 
roadShape3.lineWidth = 3 

let action3 = SKAction.rotateByAngle(CGFloat(M_PI)*0.25, duration:0) 
roadShape3.runAction(action3) 
roadShape3.position = CGPoint(x:frame.midX, y: frame.midY) 
addChild(roadShape3) 

您還可以使用applyTransform的旋轉適用於bezierPath 代替SKShapeNode如下：

let roadPath1 = UIBezierPath(ovalInRect: CGRect(x: -100, y: -25, width: 200, height: 50)) 
let roadPath2 = UIBezierPath(ovalInRect: CGRect(x: -100, y: -25, width: 200, height: 50)) 
roadPath2.applyTransform(CGAffineTransformMakeRotation(45.0 * CGFloat(M_PI)/180)) 
let roadPath3 = UIBezierPath(ovalInRect: CGRect(x: -100, y: -25, width: 200, height: 50)) 
roadPath3.applyTransform(CGAffineTransformMakeRotation(135.0 * CGFloat(M_PI)/180)) 

let roadShape1 = SKShapeNode(ellipseInRect: CGRectMake(-100, -25, 200, 50)) 
roadShape1.path = roadPath1.CGPath 
roadPath1.stroke() 
roadShape1.lineWidth = 3 
roadShape1.position = CGPoint(x:frame.midX, y: frame.midY) 
addChild(roadShape1) 

let roadShape2 = SKShapeNode(ellipseInRect: CGRectMake(-100, -25, 200, 50)) 
roadShape2.path = roadPath2.CGPath 
roadPath2.stroke() 
roadShape2.lineWidth = 3 
roadShape2.position = CGPoint(x:frame.midX, y: frame.midY) 
addChild(roadShape2) 

let roadShape3 = SKShapeNode(ellipseInRect: CGRectMake(-100, -25, 200, 50)) 
roadShape3.path = roadPath3.CGPath 
roadPath3.stroke() 
roadShape3.lineWidth = 3 
roadShape3.position = CGPoint(x:frame.midX, y: frame.midY) 
addChild(roadShape3)