Depending on what you actually need to achieve the following may help.
autoEnablesDefaultLighting is a Boolean value that determines whether SceneKit automatically adds lights to a scene or not.
By default this is set as false meaning that:
the only light sources SceneKit uses for rendering a scene are those
contained in the scene graph.
If on the other hand, this is set to true:
SceneKit automatically adds and places an omnidirectional light source
when rendering scenes that contain no lights or only contain ambient
lights.
This is located from the position of the camera and pointing in the direction of the camera.
One issue that Mark Daws noted in his excellent article is that:
The light has a changing direction, so as you walk around an object it
will always look like the light is coming from your point of view
(like you are holding a torch infront of you) which isn’t the case
normally, most scenes have static lighting so your model will look
unnatural as you move around.
isLightEstimationEnabled on the other hand:
provides light estimates in the lightEstimate property of each ARFrame
it delivers.
If you render your own overlay graphics for the AR scene, you can use
this information in shading algorithms to help make those graphics
match the real-world lighting conditions of the scene captured by the
camera. The ARSCNView class automatically uses this information to
configure SceneKit lighting.
What this means, is that if you dim the lights in your room for example, and want to apply these lighting conditions on your virtual objects to make them more realistic, this is what you want to use; since with this information we can take the lightEstimate from every frame and modify the intensity of the lights in our scene to mimic the ambient light intensity of the real world itself.
You can get details of lightingEstimate by setting:
configuration.isLightEstimationEnabled = true
And then using the following callback:
//--------------------------
// MARK: - ARSCNViewDelegate
//--------------------------
extension ViewController: ARSCNViewDelegate{
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
guard let lightEstimate = self.augmentedRealityView.session.currentFrame?.lightEstimate else { return }
let ambientLightEstimate = lightEstimate.ambientIntensity
let ambientColourTemperature = lightEstimate.ambientColorTemperature
print(
"""
Current Light Estimate = \(ambientLightEstimate)
Current Ambient Light Colour Temperature Estimate = \(ambientColourTemperature)
""")
if ambientLightEstimate < 100 { print("Lighting Is Too Dark") }
}
}
You then need to do something with the values returned and apply them to your sceneLights.
Putting it into practice therefore a very basic example might look like so:
//--------------------------
// MARK: - ARSCNViewDelegate
//--------------------------
extension ViewController: ARSCNViewDelegate{
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
//1. Get The Current Light Estimate
guard let lightEstimate = self.augmentedRealityView.session.currentFrame?.lightEstimate else { return }
//2. Get The Ambient Intensity & Colour Temperatures
let ambientLightEstimate = lightEstimate.ambientIntensity
let ambientColourTemperature = lightEstimate.ambientColorTemperature
print(
"""
Current Light Estimate = \(ambientLightEstimate)
Current Ambient Light Colour Temperature Estimate = \(ambientColourTemperature)
""")
if ambientLightEstimate < 100 { print("Lighting Is Too Dark") }
//3. Adjust The Scene Lighting
sceneLight.intensity = ambientLightEstimate
sceneLight.temperature = ambientColourTemperature
}
}
class ViewController: UIViewController {
//1. Create A Reference To Our ARSCNView In Our Storyboard Which Displays The Camera Feed
@IBOutlet weak var augmentedRealityView: ARSCNView!
@IBOutlet weak var takeSnapshotButton: UIButton!
//2. Create Our ARWorld Tracking Configuration
let configuration = ARWorldTrackingConfiguration()
//3. Create Our Session
let augmentedRealitySession = ARSession()
//4. Create Our Light
var sceneLight: SCNLight!
//-----------------------
// MARK: - View LifeCycle
//-----------------------
override func viewDidLoad() {
//2. Setup The ARSession
setupARSession()
//2. Generate Our Scene
generateScene()
super.viewDidLoad()
}
override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() }
//-------------------------
// MARK: - Scene Generation
//-------------------------
/// Creates An SCNNode & Light For Our Scene
func generateScene(){
//1. Create An SCNNode With An SCNSphere Geometry
let sphereNode = SCNNode()
let sphereGeometry = SCNSphere(radius: 0.2)
sphereGeometry.firstMaterial?.diffuse.contents = UIColor.cyan
sphereNode.geometry = sphereGeometry
sphereNode.position = SCNVector3(0, 0, -1.5)
//2. Create Our Light & Position It
sceneLight = SCNLight()
sceneLight.type = .omni
let lightNode = SCNNode()
lightNode.light = sceneLight
lightNode.position = SCNVector3(0,0,2)
//3. Add The Node & Light To Out Scene
self.augmentedRealityView.scene.rootNode.addChildNode(sphereNode)
self.augmentedRealityView.scene.rootNode.addChildNode(lightNode)
}
//-----------------
//MARK: - ARSession
//-----------------
/// Sets Up The ARSession
func setupARSession(){
//1. Set The AR Session
augmentedRealityView.session = augmentedRealitySession
augmentedRealityView.delegate = self
configuration.isLightEstimationEnabled = true
augmentedRealityView.automaticallyUpdatesLighting = false
augmentedRealityView.autoenablesDefaultLighting = false
augmentedRealityView.session.run(configuration, options:[.resetTracking, .removeExistingAnchors])
}
}
Hope it helps...
