I am building a macOS SwiftUI app. I want to show the world axis such that the user is aware of the orientation of objects. I've looked at the

SwiftUI mac version

import SwiftUI
import SceneKit

struct ContentView : View {
    
    @State private var scene = SCNScene()
    @State private var axis = SCNNode()
    var options: SceneView.Options = [.allowsCameraControl]
    
    var body: some View {
        ZStack {
            SceneView(scene: scene, options: options).ignoresSafeArea()
            let _ = scene.background.contents = NSColor.black
            let _ = createWorldAxis()
            let _ = axis.opacity = 0.1          // you can hide world axis
        }
    }
    
    func createWorldAxis() {
            
        let colors: [NSColor] = [.systemRed, .systemGreen, .systemBlue]

        for index in 0...2 {
            
            let box = SCNBox(width: 0.200, height: 0.005,
                            length: 0.005, chamferRadius: 0.001)
            
            let material = SCNMaterial()
            material.lightingModel = .constant
            material.diffuse.contents = colors[index]
            box.materials[0] = material
            
            let node = SCNNode(geometry: box)
            
            switch index {
                case 0:
                    node.position.x  = 0.1
                case 1:
                    node.eulerAngles = SCNVector3(0, 0, Float.pi/2)
                    node.position.y  = 0.1
                case 2:
                    node.eulerAngles = SCNVector3(0, -Float.pi/2, 0)
                    node.position.z  = 0.1
                default: break
            }    
            axis.addChildNode(node)
            axis.scale = SCNVector3(1.5, 1.5, 1.5)
            scene.rootNode.addChildNode(axis)                
        }
        print(axis.position)
    }
}

Cocoa version

import Cocoa
import SceneKit

class ViewController : NSViewController {
    
    var axis = SCNNode()
    var sceneView = SCNView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        sceneView = self.view as! SCNView
        sceneView.scene = SCNScene()
        sceneView.allowsCameraControl = true
        sceneView.backgroundColor = .black
      
        self.createWorldAxis()
        axis.opacity = 0.1                     // you can hide world axis
    }
    
    func createWorldAxis() {
        
        let colors: [NSColor] = [.systemRed, .systemGreen, .systemBlue]

        for index in 0...2 {
            
            let box = SCNBox(width: 0.200, height: 0.005, 
                            length: 0.005, chamferRadius: 0.001)
            
            let material = SCNMaterial()
            material.lightingModel = .constant
            material.diffuse.contents = colors[index]
            box.materials[0] = material
            
            let node = SCNNode(geometry: box)

            if index == 0 {
                node.position.x  = 0.1    
            } else if index == 1 {
                node.eulerAngles = SCNVector3(0, 0, Float.pi/2)
                node.position.y  = 0.1    
            } else if index == 2 {
                node.eulerAngles = SCNVector3(0, -Float.pi/2, 0)
                node.position.z  = 0.1
            }
            axis.addChildNode(node)
            axis.scale = SCNVector3(1.5, 1.5, 1.5)
            sceneView.scene?.rootNode.addChildNode(axis)                
        }
        print(axis.position)
    }
}

CodePudding user response：

I found what i wanted using the UI. First, ensure you enable controls for your scene:

myscene.showsStatistics = true

Then, click the configuration button on the bottom of your screen.

In the options dropdown select World Origin.

I am puzzled why all debug options can be invoked programmatically except the World Origin. None the less, that allows you to see axis.