SceneKit cube rotation with multiple UIPanGestureRecognizers - ios

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
}
}
}

Answer 1

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

Answer 2

The way you set up your two gesture recognizers is identical, they will both fire for the same events (which is why the last one to be added predominates). There is no control within pan to specifically limit it to vertical or horizontal pans. Instead, consider analyzing the direction of the pan and then decide whether to rotate your gesture one way or the other, based upon which is greater.