Get vector in SCNNode environment from touch location swift

问题

I have the position and orientation of my camera, the CGPoint touch location on the screen, I need the line (preferably vector) in the direction that I touched on the screen in my 3d SCNNode environment, how can I get this?
A code snippet would be very helpful.

回答1:

You can use the SCNSceneRenderer.unprojectPoint(_:) method for this.

This method, which is implemented by SCNView, takes the coordinates of your point as a SCNVector3. Set the first two elements in the coordinate space of your view. Apple describes the use of the third element:

The z-coordinate of the point parameter describes the depth at which to unproject the point relative to the near and far clipping planes of the renderer’s viewing frustum (defined by its pointOfView node). Unprojecting a point whose z-coordinate is 0.0 returns a point on the near clipping plane; unprojecting a point whose z-coordinate is 1.0 returns a point on the far clipping plane.

You are not looking for the location of these points, but for the line that connects them. Just subtract both to get the line.

func getDirection(for point: CGPoint, in view: SCNView) -> SCNVector3 {
    let farPoint  = view.unprojectPoint(SCNVector3Make(point.x, point.y, 1))
    let nearPoint = view.unprojectPoint(SCNVector3Make(point.x, point.y, 0))

    return SCNVector3Make(farPoint.x - nearPoint.x, farPoint.y - nearPoint.y, farPoint.z - nearPoint.z) 
}

来源：https://stackoverflow.com/questions/44991038/get-vector-in-scnnode-environment-from-touch-location-swift