I'm attempting my first SceneKit app. My goal is to simulate a view from the surface of the Earth and being able to point the device's camera in any direction and overlay information over the camera view.
To start, I'm simply trying to get the SceneKit camera view to match the device's orientation. To verify that it is working as desired, I am adding a bunch of spheres at specific latitude and longitude coordinates.
Everything is working except for one important issue. The view is mirrored left/right (east/west) from what it should be showing. I've spent hours trying different permutations of adjusting the camera.
Below is my complete test app view controller. I can't figure out the right combination of changes to get the scene to render properly. The sphere at the North Pole is correct. The line of spheres stretching from the North Pole to the equator at my own current longitude appears overhead as expected. It's the other lines of spheres that are incorrect. They are mirrored east/west from what they should be as if the mirror is at my own longitude.
If you want to test this code, create a new Game project with SceneKit. Replace the template GameViewController.swift file with the one below. You also need to add the "Privacy - Location When In Use Description" key to the Info.plist. I also suggest adjusting the for lon in ... line so the numbers either start or end with your own longitude. Then you can see whether the spheres are being drawn on the correct portion of the display. This might also require a slight adjustment to the UIColor(hue: CGFloat(lon + 104) * 2 / 255.0 color.
import UIKit
import QuartzCore
import SceneKit
import CoreLocation
import CoreMotion
let EARTH_RADIUS = 6378137.0
class GameViewController: UIViewController, CLLocationManagerDelegate {
var motionManager: CMMotionManager!
var scnCameraArm: SCNNode!
var scnCamera: SCNNode!
var locationManager: CLLocationManager!
var pitchAdjust = 1.0
var rollAdjust = -1.0
var yawAdjust = 0.0
func radians(_ degrees: Double) -> Double {
return degrees * Double.pi / 180
}
func degrees(_ radians: Double) -> Double {
return radians * 180 / Double.pi
}
func setCameraPosition(lat: Double, lon: Double, alt: Double) {
let yaw = lon
let pitch = lat
scnCameraArm.eulerAngles.y = Float(radians(yaw))
scnCameraArm.eulerAngles.x = Float(radians(pitch))
scnCameraArm.eulerAngles.z = 0
scnCamera.position = SCNVector3(x: 0.0, y: 0.0, z: Float(alt + EARTH_RADIUS))
}
func setCameraPosition(loc: CLLocation) {
setCameraPosition(lat: loc.coordinate.latitude, lon: loc.coordinate.longitude, alt: loc.altitude)
}
// MARK: - UIViewController methods
override func viewDidLoad() {
super.viewDidLoad()
// create a new scene
let scene = SCNScene()
let scnCamera = SCNNode()
let camera = SCNCamera()
camera.zFar = 2.5 * EARTH_RADIUS
scnCamera.camera = camera
scnCamera.position = SCNVector3(x: 0.0, y: 0.0, z: Float(EARTH_RADIUS))
self.scnCamera = scnCamera
let scnCameraArm = SCNNode()
scnCameraArm.position = SCNVector3(x: 0, y: 0, z: 0)
scnCameraArm.addChildNode(scnCamera)
self.scnCameraArm = scnCameraArm
scene.rootNode.addChildNode(scnCameraArm)
// create and add an ambient light to the scene
let ambientLightNode = SCNNode()
ambientLightNode.light = SCNLight()
ambientLightNode.light!.type = .ambient
ambientLightNode.light!.color = UIColor.darkGray
scene.rootNode.addChildNode(ambientLightNode)
// retrieve the SCNView
let scnView = self.view as! SCNView
// set the scene to the view
scnView.scene = scene
//scnView.pointOfView = scnCamera
// Draw spheres over part of the western hemisphere
for lon in stride(from: 0, through: -105, by: -15) {
for lat in stride(from: 0, through: 90, by: 15) {
let mat4 = SCNMaterial()
if lat == 90 {
mat4.diffuse.contents = UIColor.yellow
} else if lat == -90 {
mat4.diffuse.contents = UIColor.orange
} else {
//mat4.diffuse.contents = UIColor(red: CGFloat(lat + 90) / 255.0, green: CGFloat(lon + 104) * 4 / 255.0, blue: 1, alpha: 1)
mat4.diffuse.contents = UIColor(hue: CGFloat(lon + 104) * 2 / 255.0, saturation: 1, brightness: CGFloat(255 - lat * 2) / 255.0, alpha: 1)
}
let ball = SCNSphere(radius: 100000)
ball.firstMaterial = mat4
let ballNode = SCNNode(geometry: ball)
ballNode.position = SCNVector3(x: 0.0, y: 0.0, z: Float(100000 + EARTH_RADIUS))
let ballArm = SCNNode()
ballArm.position = SCNVector3(x: 0, y: 0, z: 0)
ballArm.addChildNode(ballNode)
scene.rootNode.addChildNode(ballArm)
ballArm.eulerAngles.y = Float(radians(Double(lon)))
ballArm.eulerAngles.x = Float(radians(Double(lat)))
}
}
// configure the view
scnView.backgroundColor = UIColor(red: 0, green: 191/255, blue: 255/255, alpha: 1) // sky blue
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBestForNavigation
let auth = CLLocationManager.authorizationStatus()
switch auth {
case .authorizedWhenInUse:
locationManager.startUpdatingLocation()
case .notDetermined:
locationManager.requestWhenInUseAuthorization()
default:
break
}
motionManager = CMMotionManager()
motionManager.deviceMotionUpdateInterval = 1 / 30
motionManager.startDeviceMotionUpdates(using: .xTrueNorthZVertical, to: OperationQueue.main) { (motion, error) in
if error == nil {
if let motion = motion {
//print("pitch: (self.degrees(motion.attitude.roll * self.pitchAdjust)), roll: (self.degrees(motion.attitude.pitch * self.rollAdjust)), yaw: (self.degrees(-motion.attitude.yaw))")
self.scnCamera.eulerAngles.z = Float(motion.attitude.yaw + self.yawAdjust)
self.scnCamera.eulerAngles.x = Float(motion.attitude.roll * self.pitchAdjust)
self.scnCamera.eulerAngles.y = Float(motion.attitude.pitch * self.rollAdjust)
}
}
}
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if UIApplication.shared.statusBarOrientation == .landscapeRight {
pitchAdjust = -1.0
rollAdjust = 1.0
yawAdjust = Double.pi
} else {
pitchAdjust = 1.0
rollAdjust = -1.0
yawAdjust = 0.0
}
}
override var shouldAutorotate: Bool {
return false
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .landscape
}
// MARK: - CLLocationManagerDelegate methods
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
if status == .authorizedWhenInUse {
manager.startUpdatingLocation()
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
for loc in locations {
print(loc)
if loc.horizontalAccuracy > 0 && loc.horizontalAccuracy <= 100 {
setCameraPosition(loc: loc)
}
}
}
func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
}
}
The changes probably need to be made in some combination of the setCameraPosition method and/or the motionManager.startDeviceMotionUpdates closure at the end of viewDidLoad.
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