RealityKit – How to disable default lighting in `.nonAR` ARView?

Question

I am learning Apple's RealityKit for the first time and created the sphere in the code below. Without creating/adding any light source to the scene, the sphere is already fully lit all around in the preview and you can even see light source reflections on its surface.

Since I didn't create a light source, I expect at this point, to see just a black screen. When I uncomment the part of the code which does create a point light, I expect to see the sphere lit ONLY from the right side, with the opposite side completely dark.

I tried arView.renderOptions = [.disableAREnvironmentLighting] but this does nothing. Been scouring google searches for the past hour and cannot find a solution to this. Any help is appreciated.

import SwiftUI
import RealityKit

struct ARViewContainer : UIViewRepresentable {
    func makeUIView(context: Context) -> ARView {

        let arView = ARView(frame: .zero,
                            cameraMode: .nonAR,
                            automaticallyConfigureSession: false)

        arView.renderOptions = [.disableAREnvironmentLighting]
        
        /*let pointLight = PointLight()
        pointLight.light.intensity = 100000
        let lightAnchor = AnchorEntity(world: [1,0,0])
        lightAnchor.addChild(pointLight)
        arView.scene.addAnchor(lightAnchor)*/
        
        var sphereMaterial = SimpleMaterial()
        sphereMaterial.roughness = MaterialScalarParameter(floatLiteral: 0)
        let sphereEntity = ModelEntity(mesh: .generateSphere(radius: 0.5), materials: [sphereMaterial])
        let sphereAnchor = AnchorEntity(world: .zero)
        sphereAnchor.addChild(sphereEntity)
        arView.scene.anchors.append(sphereAnchor)
        
        return arView
    }
    func updateUIView(_ view: ARView, context: Context) { }
}
struct ContentView : View {
    var body: some View {
        ARViewContainer().ignoresSafeArea()
    }
}

Code result:

Answer 1

Disabling default environment lighting in ARView

Since the common approach to disable HDR lighting in a RealityKit scene does not work, I propose a method that will help you bypass this limitation.

arView.environment.lighting.resource = nil       // not working

To disable a lighting environment resource data in AR scene, make a folder with a name that ends in .skybox, and place a single rectangular black .jpg, .png, .hdr or .exr image inside. Then drag the folder into your Xcode project file navigator. In the options pane, choose to create a folder reference (not a group), and add the folder to your app’s target. At build time, Xcode compiles the image for use as an environment resource and inserts the result into the app bundle.

Here's a code:

import SwiftUI
import RealityKit

struct ContentView : View {
    @State var arView = ARView(frame: .zero)
    
    var body: some View {
        ARViewContainer(arView: arView)
            .ignoresSafeArea()
            .onAppear {
                arView.cameraMode = .nonAR
                arView.environment.lighting.resource = try! .load(named: "black")
            }
    }
}

---

struct ARViewContainer : UIViewRepresentable {
    var arView: ARView
    
    func makeUIView(context: Context) -> ARView {
        
        var sphereMaterial = SimpleMaterial()
        sphereMaterial.roughness = .float(0.0)
        sphereMaterial.metallic = .float(0.3)

        let sphereEntity = ModelEntity(mesh: .generateSphere(radius: 0.5), 
                                  materials: [sphereMaterial])

        let sphereAnchor = AnchorEntity(world: .zero)
        sphereAnchor.addChild(sphereEntity)
        arView.scene.anchors.append(sphereAnchor)
        
        let pointLight = PointLight()
        pointLight.light.intensity = 50_000
        pointLight.light.color = .red
        pointLight.position.z = 2.0
        sphereAnchor.addChild(pointLight)

        return arView
    }

    func updateUIView(_ view: ARView, context: Context) { }
}

The following image illustrates how a red-color Point Light is composited together with RealityKit's default environment HDR light and how it looks like without it.