How to create CGPath from a SKSpriteNode in SWIFT

问题

I have a SKSpriteNode create with the level generator.

I need to create exactly the same shape using CGPath.

   self.firstSquare = childNodeWithName("square") as! SKSpriteNode

   var transform = CGAffineTransformMakeRotation(self.firstSquare.zRotation)
   let rect = CGRect(origin: self.firstSquare.position, size: self.firstSquare.size)
   let firstSquareCGPath:CGPath=CGPathCreateWithRect(rect, &transform)
   print(self.firstSquare.position)

=> firstSquare position (52.8359451293945, -52.9375076293945)

To check if my CGPath has been created as I want, I created a SKShapeNode with my CGPath:

let shape:SKShapeNode=SKShapeNode(path:path)
shape.fillColor = self.getRandomColor()
addChild(shape)
print(shape.position)

=> shape position (52.8359451293945, -52.9375076293945)

The result is not what I expected.

So I don't know if my CGPath is wrong, or if it's when I convert it in SKShapeNode that I lose the initial sprite properties.

To understand why I need to do that, please read this stack

EDIT 1,2

I added:

shape.position = self.firstSquare.position

And I obtained:

EDIT 3 :

I updated my explanations above, the anchor point of my firstSquare is now (0.5, 0.5)

回答1:

Usually I don't use .SKS files, I preefer to write only code, but here seems you simply have two squares , one with the original .sks position, the other added in second time without any position.

If you want to overlay your first square simply:

shape.position = self.firstSquare.position

EDIT:

I also seen your anchorPoint was setted to (0.0,0.0) but the default anchor point is (0.5,0.5). Try to correct also this parameter to match with your sks.

You .sks size layout could be not the same as scene, so:

scene.size = skView.bounds.size

Please take a look also to this parameter to change before you present your scene:

scene.scaleMode = .ResizeFill

In fact, the scale mode affects also to the positioning.

What is scaleMode?

The scaleMode of a scene determines how the scene will be updated to fill the view when the iOS device is rotated. There are four different scaleModes defined:

SKSceneScaleModeFill – the x and y axis are each scaled up or down so that the scene fills the view. The content of the scene will not maintain its current aspect ratio. This is the default if you do not specify a scaleMode for your scene.

SKSceneScaleModeAspectFill – both the x and y scale factors are calculated. The larger scale factor will be used. This ensures that the view will be filled, but will usually result in parts of the scene being cropped. Images in the scene will usually be scaled up but will maintain the correct aspect ratio.

SKSceneScaleModeAspectFit – both the x and y scale factors are calculated. The smaller scale factor will be used. This ensures that the entire scene will be visible, but will usual result in the scene being letterboxed. Images in the scene will usually be scaled down but will maintain the correct aspect ratio.

SKSceneScaleModeResizeFill – The scene is not scaled. It is simply resized so that its fits the view. Because the scene is not scaled, the images will all remain at their original size and aspect ratio. The content will all remain relative to the scene origin (lower left).

回答2:

I found a solution, I need to use SKShapeNode(path:, centered:), then apply the transformation and set the position.

self.firstSquare = childNodeWithName("square") as! SKSpriteNode

let firstSquareCGPath:CGPath=CGPath(rect: CGRect(origin: self.firstSquare.position, size: self.firstSquare.size), transform: nil)

let shape:SKShapeNode=SKShapeNode(path: firstSquareCGPath, centered: true) //important
shape.zRotation = self.firstSquare.zRotation
shape.position = self.firstSquare.position
shape.fillColor = SKColor.blue()
addChild(shape)

It works perfectly!

Just a pending question, as I set the transformation and the position in last (because of the SKShapeNode properties), I don't know if my CGPath above is set correctly (like my SKSpriteNode).

来源：https://stackoverflow.com/questions/37897837/how-to-create-cgpath-from-a-skspritenode-in-swift

标签

ios

swift

sprite-kit

skspritenode

cgpath