我有一个简单的球体和一个UITapGestureRecognizer.当轻拍时,我想施加一个使球体远离相机的力.
func sceneTapped(recognizer: UITapGestureRecognizer) {
let sceneView = self.view as! SCNView
let location = recognizer.locationInView(sceneView)
let results = sceneView.hitTest(location,options: nil)
if results.count > 0 {
let result = results[0] as SCNHitTestResult
let node = result.node
if (node.name == "foo") {
let force = SCNVector3(0,-3) // <-- Not correct. How to calculate?
node.physicsBody?.applyForce(force,impulse: true)
}
}
}
我可以在任何随机的方向移动球我硬编码(见上面的注释),但我怎么去计算“远离相机”？
我尝试从相机中取出-z方向的矢量(我认为它正在寻找它)并尝试将其转换为我感兴趣的节点的矢量：
let force = SCNVector3(0,-3)
let convertedForce = node.parentNode!.convertPosition(force,fromNode: cameraNode)
node.physicsBody?.applyForce(convertedForce,impulse: true)
这不起作用.节点以错误的方向移动.
解决方法
SCNView的
pointOfView属性将返回对场景中包含摄像头的节点的引用.正是这个节点的变换矩阵决定了摄像机的视图.那你可以
pull the z-axis out of this matrix.
func cameraZaxis(view:SCNView) -> SCNVector3 {
let cameraMat = view.pointOfView!.transform
return SCNVector3Make(cameraMat.m31,cameraMat.m32,cameraMat.m33)
}
applyForce在全局坐标系中应用force,所以在这种情况下我不相信你需要跨坐标系转换它.
