iOS 11 ARKit : Drag Object in 3D View - ios

Question

I have a node object in 3d view and i need to drag that object,
So far i have tried from here : Placing, Dragging and Removing SCNNodes in ARKit
and converted in swift
#objc func handleDragGesture(_ gestureRecognizer: UIGestureRecognizer) {
let tapPoint = gestureRecognizer.location(in: self.sceneView)
switch gestureRecognizer.state {
case .began:
print("Object began to move")
let hitResults = self.sceneView.hitTest(tapPoint, options: nil)
if hitResults.isEmpty { return }
let hitResult = hitResults.first
if let node = hitResult?.node.parent?.parent?.parent {
self.photoNode = node
}
case .changed:
print("Moving object position changed")
if let _ = self.photoNode {
let hitResults = self.sceneView.hitTest(tapPoint, types: .featurePoint)
let hitResult = hitResults.last
if let transform = hitResult?.worldTransform {
let matrix = SCNMatrix4FromMat4(transform)
let vector = SCNVector3Make(matrix.m41, matrix.m42, matrix.m43)
self.photoNode?.position = vector
}
}
case .ended:
print("Done moving object")
default:
break
}
}
but it is not working properly. what is the correct way to do?

Answer 1

You can do this using panGestureRecongniser... see basic swift Playground code for handling a SCNNode.
import UIKit
import ARKit
import SceneKit
import PlaygroundSupport
public var textNode : SCNNode?
// Main ARKIT ViewController
class ViewController : UIViewController, ARSCNViewDelegate, ARSessionDelegate {
var textNode: SCNNode!
var counter = 0
#IBOutlet var sceneView: ARSCNView!
override func viewDidLoad() {
super.viewDidLoad()
// set the views delegate
sceneView.delegate = self as! ARSCNViewDelegate
// show statistics such as fps and timing information
sceneView.showsStatistics = true
// Create a new scene
sceneView.scene.rootNode
// Add ligthing
sceneView.autoenablesDefaultLighting = true
let text = SCNText(string: "Drag Me with Pan Gesture!", extrusionDepth: 1)
// create material
let material = SCNMaterial()
material.diffuse.contents = UIColor.green
text.materials = [material]
//Create Node object
textNode = SCNNode()
textNode.name = "textNode"
textNode.scale = SCNVector3(x:0.004,y:0.004,z:0.004)
textNode.geometry = text
textNode.position = SCNVector3(x: 0, y:0.02, z: -1)
// add new node to root node
self.sceneView.scene.rootNode.addChildNode(textNode)
// Add pan gesture for dragging the textNode about
sceneView.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(panGesture(_:))))
}
override func loadView() {
sceneView = ARSCNView(frame:CGRect(x: 0.0, y: 0.0, width: 500.0, height: 600.0))
// Set the view's delegate
sceneView.delegate = self
let config = ARWorldTrackingConfiguration()
config.planeDetection = .horizontal
// Now we'll get messages when planes were detected...
sceneView.session.delegate = self
self.view = sceneView
sceneView.session.run(config)
}
#objc func panGesture(_ gesture: UIPanGestureRecognizer) {
gesture.minimumNumberOfTouches = 1
let results = self.sceneView.hitTest(gesture.location(in: gesture.view), types: ARHitTestResult.ResultType.featurePoint)
guard let result: ARHitTestResult = results.first else {
return
}
let position = SCNVector3Make(result.worldTransform.columns.3.x, result.worldTransform.columns.3.y, result.worldTransform.columns.3.z)
textNode.position = position
}
}
PlaygroundPage.current.liveView = ViewController()
PlaygroundPage.current.needsIndefiniteExecution = true
EDIT:
The above drag function only worked if you had 1 object in the view, so it was not really necessary to hit the node to start dragging. It will just drag from where ever you tapped on the screen. If you have multiple objects in the view, and you want to drag nodes independently. You could change the panGesture function to the following, detect each node tapped first:
// drags nodes independently
#objc func panGesture(_ gesture: UIPanGestureRecognizer) {
gesture.minimumNumberOfTouches = 1
let results = self.sceneView.hitTest(gesture.location(in: gesture.view), types: ARHitTestResult.ResultType.featurePoint)
guard let result: ARHitTestResult = results.first else {
return
}
let hits = self.sceneView.hitTest(gesture.location(in: gesture.view), options: nil)
if let tappedNode = hits.first?.node {
let position = SCNVector3Make(result.worldTransform.columns.3.x, result.worldTransform.columns.3.y, result.worldTransform.columns.3.z)
tappedNode.position = position
}
}

Answer 2

REF: https://stackoverflow.com/a/48220751/5589073
This code works for me
private func drag(sender: UIPanGestureRecognizer) {
switch sender.state {
case .began:
let location = sender.location(in: self.sceneView)
guard let hitNodeResult = self.sceneView.hitTest(location,
options: nil).first else { return }
self.PCoordx = hitNodeResult.worldCoordinates.x
self.PCoordy = hitNodeResult.worldCoordinates.y
self.PCoordz = hitNodeResult.worldCoordinates.z
case .changed:
// when you start to pan in screen with your finger
// hittest gives new coordinates of touched location in sceneView
// coord-pcoord gives distance to move or distance paned in sceneview
let hitNode = sceneView.hitTest(sender.location(in: sceneView), options: nil)
if let coordx = hitNode.first?.worldCoordinates.x,
let coordy = hitNode.first?.worldCoordinates.y,
let coordz = hitNode.first?.worldCoordinates.z {
let action = SCNAction.moveBy(x: CGFloat(coordx - self.PCoordx),
y: CGFloat(coordy - self.PCoordy),
z: CGFloat(coordz - self.PCoordz),
duration: 0.0)
self.photoNode.runAction(action)
self.PCoordx = coordx
self.PCoordy = coordy
self.PCoordz = coordz
}
sender.setTranslation(CGPoint.zero, in: self.sceneView)
case .ended:
self.PCoordx = 0.0
self.PCoordy = 0.0
self.PCoordz = 0.0
default:
break
}
}