SceneKit. How to achieve default scene light behavior without autoenablesDefaultLighting? - swift

Question

I tried to set autoenablesDefaultLighting=true for my SCNView and it looks good. However i want to achieve the same behavior without autoenablesDefaultLighting with setting light and adjust it a little bit.
I tried omni light with this code:
let lightNode = SCNNode()
lightNode.light = SCNLight()
lightNode.light?.castsShadow = true
lightNode.light?.type = .omni
lightNode.light?.intensity = 10000
lightNode.position = SCNVector3(x: 0, y: 0, z: 100)
scene.rootNode.addChildNode(lightNode)
And got this:
And with autoenablesDefaultLighting=true I got this:

Answer 1

Custom Default Lighting
I believe, in SceneKit, the default scene lighting is a Directional Light without any shadows, attached directly to the default camera node (i.e. pointOfView node). To simulate the same lighting conditions as when the .autoenablesDefaultLighting property is true, use the following code:
Delegate's renderer method – light's position orientation will be updated 60 times per second:
import SceneKit
extension GameViewController: SCNSceneRendererDelegate {
func renderer(_ renderer: SCNSceneRenderer,
updateAtTime time: TimeInterval) {
sunNode.transform = (sceneView?.pointOfView?.worldTransform)!
let cameraAngles = (self.sceneView?.pointOfView?.eulerAngles)!
let lightAngles = self.sunNode.eulerAngles
print("Camera: " + String(format: "%.2f, %.2f, %.2f", cameraAngles.x,
cameraAngles.y,
cameraAngles.z))
print("Light: " + String(format: "%.2f, %.2f, %.2f", lightAngles.x,
lightAngles.y,
lightAngles.z))
}
}
Here's GameViewController class:
class GameViewController: NSViewController {
var sceneView: SCNView? = nil
let sunNode = SCNNode()
override func viewDidLoad() {
super.viewDidLoad()
sceneView = self.view as? SCNView
sceneView?.delegate = self
let scene = SCNScene(named: "ship.scn")!
sceneView?.scene = scene
sceneView?.scene?.lightingEnvironment.contents = .none
sceneView?.scene?.background.contents = .none
sceneView?.backgroundColor = .black
sceneView?.allowsCameraControl = true
// sceneView?.autoenablesDefaultLighting = true
sunNode.light = SCNLight()
sunNode.light?.type = .directional
sceneView?.scene?.rootNode.addChildNode(sunNode)
}
}
Explanations
I'd like to add that if there is no light in the scene at all (including the autoenablesDefaultLighting parameter), then the only uncontrollable source of light in the scene will be the non-switchable Ambient Light.
In addition to the above, the Physically Based shader always requires additional Ambient Light fixture (otherwise the physically based surface will be black). The location and orientation of this light source does not matter.
If Directional Light illuminates the surface perpendicularly, then the surface is illuminated with 100% intensity (default intensity is 1000 lumens), but if the rays of the light source are parallel to the surface, then the surface is not illuminated by this source.
As you can see, the first and last images have identical lighting environment.