Search code examples
swiftxcodesprite-kitskphysicsbody

How can I make an SKPhysicsBody for this image using CGPath?

I am trying to make an SKPhysics body for this SKSpriteNode using a CGPath polygon.

enter image description here

The problem is that when I check for a collision between this node and the player node, the didBeginContact method is executed even though they did not touch each other. I believe their is something wrong with the coordinates but I cannot see the polygon lines, which makes it difficult for me too see the accuracy of the lines.

Here is the code that I am using:

 let triangle = SKSpriteNode(imageNamed: "Triangle_ZigZag")
 let trianglePath = CGMutablePath()

 trianglePath.addLines(between: [CGPoint(x: triangle.size.width, 
                                 y: triangle.size.height),

                                CGPoint(x: triangle.size.width, 
                                 y: - triangle.size.height),

                                 CGPoint(x: -triangle.size.width,
                                 y: triangle.size.height / 2)])

 trianglePath.closeSubpath()
 triangle.physicsBody = SKPhysicsBody(polygonFrom: trianglePath)

Can someone please help me figure out what am I doing wrong ?

Thank You

Solution

  • FYI physics lines are green, so a green sprite probably isn't the best choice you can't see the lines very well.

    your sprite has a centre anchorPoint or an anchorPoint of (0, 0) by default. Therefore your physics points need to take that into account. top right corner would be half the width from centre and half the height from centre etc. You have full width from centre and full height from centre, that is the issue.

    trianglePath.addLines(between: [CGPoint(x: triangle.size.width / 2, y: triangle.size.height / 2), CGPoint(x: triangle.size.width / 2, y: -triangle.size.height / 2), CGPoint(x: -triangle.size.width / 2, y: 0)])