Orbital-SceneKit-sample.swift

import SceneKit
import PlaygroundSupport

var sceneView = SCNView()
PlaygroundPage.current.liveView = sceneView
sceneView.backgroundColor = .black
var scene = SCNScene()
sceneView.scene = scene
var universe = scene.rootNode

var camera = SCNCamera()
var observer = SCNNode()
observer.camera = camera
observer.position = SCNVector3(x: 0, y: 15, z: 50)
universe.addChildNode(observer)

var light = SCNLight()
light.type = .directional
var torch = SCNNode()
torch.light = light
torch.position = SCNVector3(x: 5, y: 20, z: 60)
universe.addChildNode(torch)

var sunObject = SCNSphere(radius: 3)
var sunMaterial = sunObject.firstMaterial!
sunMaterial.diffuse.contents  = UIColor.yellow
var sun = SCNNode(geometry: sunObject)
universe.addChildNode(sun)
observer.look(at: sun.position)
torch.look(at: sun.position)

var earthOrbit = SCNNode()
sun.addChildNode(earthOrbit)
var earthObject = SCNSphere(radius: 1)
var earthMaterial = earthObject.firstMaterial!
earthMaterial.diffuse.contents  = UIColor.blue
var earth = SCNNode(geometry: earthObject)
earthOrbit.addChildNode(earth)
earth.position = SCNVector3(x: -12, y: 0, z: 0)
earthOrbit.runAction(
    .repeatForever(
        .rotateBy(x: 0, y: 2 * CGFloat.pi, z: 0, duration: 10)))

var moonOrbit = SCNNode()
earth.addChildNode(moonOrbit)
var moonObject = SCNSphere(radius: 0.5)
var moonMaterial = moonObject.firstMaterial!
moonMaterial.diffuse.contents  = UIColor.gray
var moon = SCNNode(geometry: moonObject)
moonOrbit.addChildNode(moon)
moon.position = SCNVector3(x: -2, y: 0, z: 0)
moonOrbit.runAction(
    .repeatForever(
        .rotateBy(x: 0, y: 2 * CGFloat.pi, z: 0, duration: 1)))