Orienting a directional light and adding to scene in ARKit - swift

Question

I have found a few great examples how to add a directional light to my code, but not how to change the orientation as well as add it to my scene. How do I do this with my code? Here is my light class:
class Lighting: Entity, HasDirectionalLight {
required init() {
super.init()
self.light = DirectionalLightComponent(color: .white,
intensity: 100000,
isRealWorldProxy: true)
}
}
And here is the function that calls it:
func addTableToPlane(arView: ARView) {
let tableAnchor = AnchorEntity(plane: .horizontal)
let table = try! Entity.load(named: "Table_1500")
tableAnchor.addChild(table)
let dirLight = Lighting().light
let shadow = Lighting().shadow
tableAnchor.components.set(shadow!)
tableAnchor.components.set(dirLight)
}
I'm a pretty new to ARKit, so I haven't figured out how to edit the orientation of the directional light as I have it.
Another unsuccessful method that I tried was to create a lighting function, but I haven't been able to figure out how to add it to the scene:
func addLights(arView: ARView) {
// 1
let directionalLight = SCNLight()
directionalLight.type = .directional
directionalLight.intensity = 500
// 2
directionalLight.castsShadow = true
directionalLight.shadowMode = .deferred
// 3
directionalLight.shadowColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.5)
// 4
let directionalLightNode = SCNNode()
directionalLightNode.light = directionalLight
directionalLightNode.rotation = SCNVector4Make(1, 0, 0, -Float.pi / 3)
sceneView.scene.rootNode.addChildNode(directionalLightNode)
}
I then added addLights(arView: uiView) to the addTableToPlane function. I tried to add the light with:
arView.scene.rootNode.addChildNode(ambientLightNode)
but this gives the error that I don't have a childNode and so on. I guess that I'm spoiled with decent docs for Python that supply examples interspersed to help figure out problems, unlike the overly concise docs for Xcode, such as, what the heck I do with "Use the light’s look(at:from:upVector:relativeTo:) method to aim the light". Where do I put this? Where might I find answers to these simple questions?
Chasing my tail for the past couple days just to rotate a light is frustrating.

Answer 1

Use the following code to control orientation of directional light:
Take into consideration that position of Directional Light is not important!
import ARKit
import RealityKit
class Lighting: Entity, HasDirectionalLight, HasAnchoring {
required init() {
super.init()
self.light = DirectionalLightComponent(color: .green,
intensity: 1000,
isRealWorldProxy: true)
}
}
class ViewController: UIViewController {
#IBOutlet var arView: ARView!
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
let light = Lighting()
light.orientation = simd_quatf(angle: .pi/8,
axis: [0, 1, 0])
let boxAnchor = try! Experience.loadBox()
let directLightAnchor = AnchorEntity()
directLightAnchor.addChild(light)
boxAnchor.addChild(directLightAnchor)
boxAnchor.steelBox!.scale = [30,30,30]
boxAnchor.steelBox!.position.z = -3
arView.scene.anchors.append(boxAnchor)
}
}
If you want to know how implement directional light's orientation in SceneKit, read this post.