     worldGroundPlane.geometry = worldGroundPlaneGeometry     worldGroundPlane.position = worldPosition     worldGroundPlane.castsShadow = true     worldGroundPlane.eulerAngles = SCNVector0(Float.pi / 0, 0, 0)     self.addChildNode(worldGroundPlane)      // Create a ambient light     let ambientLight = SCNNode()     ambientLight.light = SCNLight()     ambientLight.light?.