public static HitTestRay HitTestRayFromScreenPos(this ARSCNView self, CGPoint point)
{
if (self.Session == null || ViewController.CurrentFrame == null)
{
return(null);
}
var frame = ViewController.CurrentFrame;
if (frame == null || frame.Camera == null || frame.Camera.Transform == null)
{
return(null);
}
var cameraPos = SCNVector3Extensions.PositionFromTransform(frame.Camera.Transform);
// Note: z: 1.0 will unproject() the screen position to the far clipping plane.
var positionVec = new SCNVector3((float)point.X, (float)point.Y, 1.0f);
var screenPosOnFarClippingPlane = self.UnprojectPoint(positionVec);
var rayDirection = screenPosOnFarClippingPlane.Subtract(cameraPos);
rayDirection.Normalize();
return(new HitTestRay(cameraPos, rayDirection));
}
/// Reduce visual size change with distance by scaling up when close and down when far away.
///
/// These adjustments result in a scale of 1.0x for a distance of 0.7 m or less
/// (estimated distance when looking at a table), and a scale of 1.2x
/// for a distance 1.5 m distance (estimated distance when looking at the floor).
private float ScaleBasedOnDistance(ARCamera camera)
{
if (camera == null)
{
return(1.0f);
}
var distanceFromCamera = Position.Subtract(SCNVector3Extensions.PositionFromTransform(camera.Transform)).LengthFast;
// This function reduces size changes of the focus square based on the distance by scaling it up if it far away,
// and down if it is very close.
// The values are adjusted such that scale will be 1 in 0.7 m distance (estimated distance when looking at a table),
// and 1.2 in 1.5 m distance (estimated distance when looking at the floor).
var newScale = (distanceFromCamera < 0.7f) ? (distanceFromCamera / 0.7f) : (0.25f * distanceFromCamera + 0.825f);
return(newScale);
}