SceneKit cube rotation with multiple UIPanGestureRecognizers

Question

Thanks for taking a look at this. I'm sure it is something very basic. I am a beginner.

I am trying to rotate a cube in in a SceneKit view with pan gestures. I have so far been successful in load this sample app onto my iPad and panning my finger on the y axis to rotate the cube on its x axis, or panning along the screens x-axis to rotate the cube along its y-axis.

Currently, I've noticed that whichever gesture recognizer is added last to the sceneView is the one that works. My question is how can I have the cube respond to either a x pan gesture then a y pan gesture or vice versa.

Here is the code I have written so far:

import UIKit
import SceneKit

class ViewController: UIViewController {

  //geometry
  var geometryNode: SCNNode = SCNNode()

  //gestures
  var currentYAngle: Float = 0.0
  var currentXAngle: Float = 0.0

  override func viewDidLoad() {
    super.viewDidLoad()

    sceneSetup()  
  }

  func sceneSetup () {
    //setup scene
    let scene = SCNScene()
    let sceneView = SCNView(frame: self.view.frame)
    self.view.addSubview(sceneView)

    //add camera
    let camera = SCNCamera()
    let cameraNode = SCNNode()
    cameraNode.camera = camera
    cameraNode.position = SCNVector3(x: 0.0, y: 0.0, z: 5.0)

    //add light
    let light = SCNLight()
    light.type = SCNLightTypeOmni
    let lightNode = SCNNode()
    lightNode.light = light
    lightNode.position = SCNVector3(x: 1.5, y: 1.5, z: 1.5)

    //add cube
    let cubeGeometry = SCNBox(width: 1.0, height: 1.0, length: 1.0, chamferRadius: 0.0)
    let boxNode = SCNNode(geometry: cubeGeometry)

    scene.rootNode.addChildNode(lightNode)
    scene.rootNode.addChildNode(cameraNode)
    scene.rootNode.addChildNode(boxNode)

    geometryNode = boxNode

    //add recognizers
    let panXRecognizer = UIPanGestureRecognizer(target: self, action: "rotateXGesture:")
    let panYRecognizer = UIPanGestureRecognizer(target: self, action: "rotateYGesture:")
    sceneView.addGestureRecognizer(panXRecognizer)
    sceneView.addGestureRecognizer(panYRecognizer)

    sceneView.scene = scene
  }

  func rotateXGesture (sender: UIPanGestureRecognizer) {
    let translation = sender.translationInView(sender.view)
    var newXAngle = (Float)(translation.y)*(Float)(M_PI)/180.0
    newXAngle += currentXAngle

    geometryNode.transform = SCNMatrix4MakeRotation(newXAngle, 1, 0, 0)

    if(sender.state == UIGestureRecognizerState.Ended) {
      currentXAngle = newXAngle
    }
  }

  func rotateYGesture (sender: UIPanGestureRecognizer) {
    let translation = sender.translationInView(sender.view)
    var newYAngle = (Float)(translation.x)*(Float)(M_PI)/180.0
    newYAngle += currentYAngle

    geometryNode.transform = SCNMatrix4MakeRotation(newYAngle, 0, 1, 0)

    if(sender.state == UIGestureRecognizerState.Ended) {
      currentYAngle = newYAngle
    }
  }
}

bpedit bpedit · Accepted Answer · 2016-03-03T21:55:38

Combine your current two gestures into one. Here's the relevant portion of the code I'm using:

func panGesture(sender: UIPanGestureRecognizer) {
    let translation = sender.translationInView(sender.view!)

    var newAngleX = (Float)(translation.y)*(Float)(M_PI)/180.0
    newAngleX += currentAngleX
    var newAngleY = (Float)(translation.x)*(Float)(M_PI)/180.0
    newAngleY += currentAngleY

    baseNode.eulerAngles.x = newAngleX
    baseNode.eulerAngles.y = newAngleY

    if(sender.state == UIGestureRecognizerState.Ended) {
        currentAngleX = newAngleX
        currentAngleY = newAngleY
    }
}

Here's a gesture for zooming as well:

func pinchGesture(sender: UIPinchGestureRecognizer) {
    let zoom = sender.scale
    var z = cameraNode.position.z  * Float(1.0 / zoom)
    z = fmaxf(zoomLimits.min, z)
    z = fminf(zoomLimits.max, z)

    cameraNode.position.z = z
}

Edit: I found a better way to rotate the model. In the panGesture code at the top, the x-axis pivots as you rotate about the y. This means if you rotate 180 about the y, rotation about the x is opposite your finger motion. The method also restricts motion to two degrees of freedom. The method linked to below, even though it doesn't directly affect the z-axis, somehow seems to allow three degrees of freedom. It also makes all vertical swipes rotate about the x in the logical direction. How to rotate object in a scene with pan gesture - SceneKit

SceneKit cube rotation with multiple UIPanGestureRecognizers

2 Answers