I am having trouble understanding the co-ordinate system in SpriteKit. The documentation states that a scene size is 1024x768 and the anchor point for the scene is CGPointZero (i.e. the bottom left of the scene). So in Landscape orientation the scene's CGPoint(0,0) is on the bottom left of the view - all good. However, if the ScaleMode is AspectFill then (as the documentation describes) some of the scene is cropped in portrait orientation - again that makes sense. Where I am confused is that the cropping appears to be based on an AnchorPoint of CGPoint(0.5,0.5). I.e. a sprite with AnchorPoint CGPoint(0,0) that is drawn at scene position CGPoint(0,0) is cropped in portrait orientation. My question is: "If the scene's anchor point is CGPoint(0,0) and the ScaleMode is AspectFill, why does this the node at CGPoint(0,0) cropped? Shouldn't it ensure that the bottom left of the scene is always at the bottom left of the view?"
1 Answers
Do not confuse your scene with your view.
Yes, for your scene, the default is bottom left. But scaling applies from the scene to the view. By default, your scene is added to the center of the view.
As far as scaling goes, imagine it being like a balloon that you are going to wrap around a box.
You pull it from all ends evenly till the entire balloon fits around the edges of the box.
Then you take Aspect fill into consideration by taking 2 rectangle boxes, and placing them on the sides so that your box top turns into the desired shape.
This is why (0,0) ends up getting cropped off.
The anchor point applies to what happens inside the scene, not outside.
You would need to change the views anchor point (Not possible that I know of) to achieve what you want, or just shift the scene to the right by the difference of (sceneWidth * scaleFactor) - viewWidth
