func magic() {
        guard let hat = sceneView.scene.rootNode.childNode(withName: HAT_IDENTIFIER, recursively: true) else { return }
        let hatWorldPosition = hat.worldPosition

        let (tubeMin, tubeMax): (SCNVector3, SCNVector3) = hat.boundingBox

        let minX = hatWorldPosition.x + tubeMin.x
        let minY = hatWorldPosition.y + tubeMin.y
        let minZ = hatWorldPosition.z + tubeMin.z

        let maxX = hatWorldPosition.x + tubeMax.x
        let maxY = hatWorldPosition.y + tubeMax.y
        let maxZ = hatWorldPosition.z + tubeMax.z

        for ball in balls {
            let pos = ball.presentation.worldPosition
            let isInsideHat = ((pos.x >= minX && pos.y >= minY && pos.z >= minZ) && (pos.x <= maxX && pos.y <= maxY && pos.z <= maxZ))
            let isOutsideHat = (pos.z < -1.0)
            if isInsideHat && !isOutsideHat {
                ball.isHidden = !ball.isHidden
            }
        }
    }