Normal mapping in Scenekit

Question

I am trying to add normal map for a 3D model in swift using SCNMaterial properties. The diffuse property is working but no other property including normal property is visible on the screen. When I debug to check if the node's material consists of the normal property, it shows the property exists with the image that I added. I have also checked if the normal image that I am using is correct or not in the SceneKit Editor where it works fine. I have added the code that I am using.

let node = SCNNode()
node.geometry = SCNSphere(radius: 0.1)
node.geometry!.firstMaterial!.diffuse.contents = UIColor.lightGray
node.geometry!.firstMaterial!.normal.contents = UIImage(named: "normal")
node.position = SCNVector3(0,0,0)
sceneView.scene.rootNode.addChildNode(node)

This is the output I am getting

I am expecting something like this

Answer 1

I got the solution. Since I did not enable DefaultLighting, there was no lighting in the scene. Added this to the code.

sceneView.autoenablesDefaultLighting = true

Answer 2

Given the screenshot, it seems like there is no lighting in the scene, or the material does not respond to lighting, since the sphere is not shaded. For a normal map to work, lighting has to be taken into account, because it responds to lighting direction. Have you tried creating an entirely new SCNMaterial and played with its properties? (I.E. https://developer.apple.com/documentation/scenekit/scnmaterial/lightingmodel seems interesting)

I would try setting

node.geometry!.firstMaterial!.lightingModel = .physicallyBased