SceneKit – Loading HDR or EXR lightingEnvironment has no effect - swift

Question

I tried loading an .hdr file to use it as a skybox and use its lighting informations. This is the code I used:
backgroundColor = UIColor.gray
// check if a default skybox is added
let environment = UIImage(named: "studio_small_09_2k.hdr")
scene?.lightingEnvironment.contents = environment
scene?.lightingEnvironment.intensity = 1.0
scene?.background.contents = environment
Unfortunately I recieve a grey screen and also no errors. Has anyone experience in using hdr files in SceneKit?
XCode Version: 13.2.1
iOS version: 15.3.1
hdr file: https://polyhaven.com/a/studio_small_09

Answer 1

I usually use a Cube Texture Set, where each of 6 images is square (height == width).
Also, the following cube map representations are supported:
Vertical strip as single image (height == 6 * width)
Horizontal strip as single image (6 * height == width)
Spherical projection as single image (2 * height == width)
Here's a SwiftUI code:
func makeUIView(context: Context) -> SCNView {
let sceneView = SCNView(frame: .zero)
sceneView.scene = SCNScene()
// if EXR or HDR is 2:1 spherical map, it really meets the requirements
sceneView.scene?.lightingEnvironment.contents = UIImage(named: "std.exr")
sceneView.backgroundColor = .black
sceneView.autoenablesDefaultLighting = true
sceneView.allowsCameraControl = true
let node = SCNNode()
node.geometry = SCNSphere(radius: 0.1)
node.geometry?.firstMaterial?.lightingModel = .physicallyBased
node.geometry?.firstMaterial?.metalness.contents = 1.0
sceneView.scene?.rootNode.addChildNode(node)
return sceneView
}
Pay particular attention – you need .physicallyBased lighting model to get HDR or EXR reflections.
And let's set it for BG:
sceneView.scene?.background.contents = UIImage(named: "std.exr")
Why your .exr doesn't work?
The solutions is simple: delete your .exr from project, empty the Trash and after that drag-and-drop .exr file, in Choose options for adding these files window choose Add to targets:
Now your .exr must work.