ios - 如何进行 CGPath 或 SKShapeNode 旋转

Question

我想将旋转的椭圆路径添加到一个中心点。如下图，但随机旋转椭圆。

绘制这些椭圆轨道，

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

需要让小粒子跟随那些椭圆轨道，这就是为什么我需要一条路径。

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

我使用 SKShapeNode 绘制并获取路径属性。但不幸的是，SKShapeNode 没有任何原点或 anchor 属性，所以我无法正确旋转到 SKShapeNode。你有什么建议让它旋转或以不同的方式。

提前致谢。

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)

您还可以使用 applyTransform 将旋转应用到 bezierPath 而不是 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)