Moving SCNNode in ARSCNView using a gesture - objective-c

Question

I have been trying to use UIPanGestureRecognizer to move an SCNNode attached to a UISceneView in iOS ARKit. It moves fine in the x dimension, but I cannot seem to figure out how to move it in the y direction. I have followed two different approaches, trying each without success:
How do I find my mouse point in a scene using SceneKit?
https://github.com/rajubd49/ARKit-Sample-ObjC
Any insight on why the y dimension does not seem to behave the same as the x would be greatly appreciated. Could this have something to do with motion only in the XZ plane or something? Here is the code following the GitHub sample code cited in #2 above):
==============
//Move SCNNode
- (void)handlePanGesture:(UIPanGestureRecognizer *)pagr
{
switch (pagr.state)
{
case UIGestureRecognizerStateBegan:
{
CGPoint tapPoint = [pagr locationInView:sceneView];
NSLog(#"%s tapPoint %#",__FUNCTION__,NSStringFromCGPoint(tapPoint));
NSArray *hitResults = [sceneView hitTest:tapPoint types:ARHitTestResultTypeFeaturePoint | ARHitTestResultTypeEstimatedHorizontalPlane];
lastHitTestResult = [hitResults firstObject];
}
break;
case UIGestureRecognizerStateChanged:
{
CGPoint tapPoint = [pagr locationInView:sceneView];
if (windScreenView.buttonState == GypsyTargetAdded)
{
NSArray *hitResults = [sceneView hitTest:tapPoint types:ARHitTestResultTypeFeaturePoint | ARHitTestResultTypeEstimatedHorizontalPlane];
ARHitTestResult *result = [hitResults lastObject];
[SCNTransaction begin];
SCNMatrix4 lastMatrix = SCNMatrix4FromMat4(lastHitTestResult.worldTransform);
SCNVector3 lastVector = SCNVector3Make(lastMatrix.m41, lastMatrix.m42, lastMatrix.m43);
SCNMatrix4 newMatrix = SCNMatrix4FromMat4(result.worldTransform);
SCNVector3 newVector = SCNVector3Make(newMatrix.m41, newMatrix.m42, newMatrix.m43);
CGFloat dx = newVector.x-lastVector.x;
CGFloat dy = newVector.y-lastVector.y;
SCNVector3 adjVector = SCNVector3Make(gypsyTargetNode.position.x + dx, gypsyTargetNode.position.y + dy, gypsyTargetNode.position.z);
gypsyTargetNode.position = adjVector;
[SCNTransaction commit];
NSLog(#"%s lastVector: x = %f, y = %f, z = %f",__FUNCTION__,lastVector.x,lastVector.y,lastVector.z);
NSLog(#"%s newVector: x = %f, y = %f, z = %f",__FUNCTION__,newVector.x,newVector.y,newVector.z);
NSLog(#"%s dx = %f, dy = %f",__FUNCTION__,dx,dy);
NSLog(#"%s gypsyTargetNode.position: x = %f, y = %f, z = %f",__FUNCTION__,gypsyTargetNode.position.x,gypsyTargetNode.position.y,gypsyTargetNode.position.z);
NSLog(#"%s hitResults.count: %li",__FUNCTION__,hitResults.count);
lastHitTestResult = result;
}
}
break;
case UIGestureRecognizerStateEnded:
{
lastHitTestResult = nil;
}
break;
default:
break;
}
}
and here are snippets of the output console. Note that the calculated "dx" is always .000000 .
[CalibrationController handlePanGesture:] tapPoint {207.33332824707031, 507}
[CalibrationController handlePanGesture:] lastVector: x = -0.016018, y = -0.083625, z = 0.006696
[CalibrationController handlePanGesture:] newVector: x = -0.015562, y = -0.083862, z = 0.006658
[CalibrationController handlePanGesture:] dx = 0.000456, dy = **-0.000237**
[CalibrationController handlePanGesture:] gypsyTargetNode.position: x = -0.018142, y = -0.087894, z = 0.008041
[CalibrationController handlePanGesture:] hitResults.count: 2
[CalibrationController handlePanGesture:] lastVector: x = -0.015562, y = -0.083862, z = 0.006658
[CalibrationController handlePanGesture:] newVector: x = -0.015562, y = -0.083862, z = 0.006658
[CalibrationController handlePanGesture:] dx = 0.000000, dy = **0.000000**
[CalibrationController handlePanGesture:] gypsyTargetNode.position: x = -0.018142, y = -0.087894, z = 0.008041
[CalibrationController handlePanGesture:] hitResults.count: 2
[CalibrationController handlePanGesture:] lastVector: x = -0.015562, y = -0.083862, z = 0.006658
[CalibrationController handlePanGesture:] newVector: x = -0.015150, y = -0.083862, z = 0.006565
[CalibrationController handlePanGesture:] dx = 0.000412, dy = **0.000000**
[CalibrationController handlePanGesture:] gypsyTargetNode.position: x = -0.017730, y = -0.087894, z = 0.008041
[CalibrationController handlePanGesture:] hitResults.count: 2
[CalibrationController handlePanGesture:] lastVector: x = -0.015150, y = -0.083862, z = 0.006565
[CalibrationController handlePanGesture:] newVector: x = -0.014686, y = -0.083862, z = 0.006361
[CalibrationController handlePanGesture:] dx = 0.000463, dy = **0.000000**

Answer 1

For panning gesture implement the following approach:
let myScene = SCNScene(named: "scene.scn")!
let modelNode: SCNNode = myScene.rootNode
var selectedNode: SCNNode? = nil
override func viewDidLoad() {
super.viewDidLoad()
let moveGesture = UIPanGestureRecognizer(target: self,
action: #selector(moveModel))
self.sceneView.addGestureRecognizer(moveGesture)
}
Check important conditions if any:
private func myMethod(at position: CGPoint) -> SCNNode? {
let nnn = self.sceneView.hitTest(position, options: nil).first(where: {
$0.node !== modelNode
})?.node
return nnn
}
Fill a gesture recognizer #objc method:
#objc func moveModel(_ gesture: UIPanGestureRecognizer) {
let location = gesture.location(in: self.sceneView)
switch gesture.state {
case .began:
selectedNode = myMethod(at: location)
case .changed:
guard let result = self.sceneView.hitTest(location,
types: .existingPlane).first
else {
return
}
let transform = result.worldTransform
let newPosition = SIMD3<Float>(transform.columns.3.x,
transform.columns.3.y,
transform.columns.3.z)
selectedNode?.simdPosition = newPosition
default:
selectedNode = nil
}
}