rotate object in ARkit - ios

Question

I've got a object in my scene that when I move my finger across the screen, I want the object to rotate in that direction. It's a cup on screen, and sliding my finger around on the screen should rotate the cube about the center point, but not move the cup's position. It should only rotate as long as they are actively swiping

Answer 1

Rotating an SCNNode is a fairly simple task.
You should begin by creating a variable to store the rotationAngle around the YAxis or any other that you wish to perform the rotation on e.g:
var currentAngleY: Float = 0.0
You will also need to have some way to detect the node that you want to rotate, which for this example we will call currentNode e.g.
var currentNode: SCNNode!
In this example I will just rotate around the YAxis.
If you want to use a UIPanGestureRecognizer you can do so like this:
/// Rotates An Object On It's YAxis
///
/// - Parameter gesture: UIPanGestureRecognizer
#objc func rotateObject(_ gesture: UIPanGestureRecognizer) {
guard let nodeToRotate = currentNode else { return }
let translation = gesture.translation(in: gesture.view!)
var newAngleY = (Float)(translation.x)*(Float)(Double.pi)/180.0
newAngleY += currentAngleY
nodeToRotate.eulerAngles.y = newAngleY
if(gesture.state == .ended) { currentAngleY = newAngleY }
print(nodeToRotate.eulerAngles)
}
Alternatively if you want to use a UIRotationGesture you can do something like this:
/// Rotates An SCNNode Around It's YAxis
///
/// - Parameter gesture: UIRotationGestureRecognizer
#objc func rotateNode(_ gesture: UIRotationGestureRecognizer){
//1. Get The Current Rotation From The Gesture
let rotation = Float(gesture.rotation)
//2. If The Gesture State Has Changed Set The Nodes EulerAngles.y
if gesture.state == .changed{
currentNode.eulerAngles.y = currentAngleY + rotation
}
//3. If The Gesture Has Ended Store The Last Angle Of The Cube
if(gesture.state == .ended) {
currentAngleY = currentNode.eulerAngles.y
}
}
Hope it helps...