Same color rendered differently in SpriteView vs. SceneView - swift

Question

For performance reasons I have to switch from SceneView to SpriteView in my macOS project (showing more than 63 scenes did not work with SceneView, but it does with SpriteView).
But now im facing an issue that SpriteView is rendering colors differently than SceneView. Below is a simple reproduction of the issue I am facing.
I have tried a multitude of material and lighting options, but I seem to miss something more fundamental. Help is very much appreciated.
var body: some View {
HStack {
// SpriteView
SpriteView(scene: { () -> SKScene in
let scene = SKScene()
scene.backgroundColor = .white
scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
let node = SK3DNode()
node.scnScene = self.sphereScene
scene.addChild(node)
return scene
}())
// SceneView
SceneView(scene: sphereScene,
options: [.autoenablesDefaultLighting])
}
}
var sphereScene: SCNScene {
let scnScene = SCNScene()
let ballGeometry = SCNSphere(radius: 5)
let ballNode = SCNNode(geometry: ballGeometry)
let material = SCNMaterial()
material.diffuse.contents = NSColor.purple
material.lightingModel = .physicallyBased
ballGeometry.materials = [material]
scnScene.rootNode.addChildNode(ballNode)
return scnScene
}

Answer 1

You're absolutely right: SpriteKit processes SceneKit's scenes differently than SceneKit. It's visually noticeable that the lighting intensity, blurring of highlights and decolorization of edges with 90 degree reflection are different. The main tool that can be advised in this case is the use of Ambient Light to additionally illuminate the SpriteKit scene based on the SceneKit content. You should turn a default lighting off (in order to get rid of colorization artifacts) and use regular lights. Here I used directional light.
SpriteView:
import SwiftUI
import SceneKit
import SpriteKit
struct SpriteView: NSViewRepresentable {
var scene = SKScene()
func makeNSView(context: Context) -> SKView {
let skView = SKView(frame: .zero)
skView.presentScene(scene)
scene.backgroundColor = .black
return skView
}
func updateNSView(_ uiView: SKView, context: Context) { }
}
ContentView:
struct ContentView: View {
var body: some View {
ZStack {
HStack {
SpriteView(scene: { () -> SKScene in
let scene = SKScene()
scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
let ambient = SCNNode()
ambient.light = SCNLight()
ambient.light?.type = .ambient
ambient.light?.intensity = 1200
let node = SK3DNode()
node.autoenablesDefaultLighting = false
node.scnScene = self.sphereScene
node.scnScene?.rootNode.addChildNode(ambient)
scene.addChild(node)
return scene
}() )
SceneView(scene: sphereScene, options: [])
}
}
}
var sphereScene: SCNScene {
let scnScene = SCNScene()
scnScene.background.contents = NSColor.black
let ballNode = SCNNode(geometry: SCNSphere(radius: 5.0))
let directional = SCNNode()
directional.light = SCNLight()
directional.light?.type = .directional
directional.light?.intensity = 500
scnScene.rootNode.addChildNode(directional)
let material = SCNMaterial()
material.lightingModel = .physicallyBased
material.diffuse.contents = NSColor.purple
ballNode.geometry?.materials = [material]
scnScene.rootNode.addChildNode(ballNode)
return scnScene
}
}

Answer 2

The following worked for me, correcting saturation and brightness brought me near to the SceneKit defaultLighting appearance:
// get object and manipulate
let object = scene.rootNode.childNode(withName: "object", recursively: false)
let color = NSColor(named: "\(colorNr)")?
.usingColorSpace(.displayP3) // specify color space, important!
object?.geometry?.firstMaterial?.lightingModel = .physicallyBased
// correct color for SpriteView
let color2 = NSColor(hue: color?.hueComponent ?? 0,
saturation: (color?.saturationComponent ?? 0) * 0.55,
brightness: (color?.brightnessComponent ?? 0) * 0.55 + 0.45,
alpha: 1.0)
object?.geometry?.firstMaterial?.diffuse.contents = color2
object?.geometry?.firstMaterial?.diffuse.intensity = 0.9
object?.geometry?.firstMaterial?.roughness.contents = 0.9