CameraControl2.playground

// A SceneKit based Playground to test camera position and movement
// using a camera orbit
import SceneKit
import PlaygroundSupport

// setup view
var sceneView = SCNView(frame: CGRect(x:0 , y:0, width: 480, height: 640))
var scene = SCNScene()
sceneView.scene = scene

sceneView.backgroundColor = UIColor.white
sceneView.autoenablesDefaultLighting = true
// sceneView.allowsCameraControl = true
sceneView.showsStatistics = true

// present
PlaygroundPage.current.liveView = sceneView

// add camera to the scene
let camera = SCNCamera()
camera.automaticallyAdjustsZRange = true

let cameraNode = SCNNode()
cameraNode.camera = camera
cameraNode.name = "camera"
cameraNode.position = SCNVector3(x: 0, y: 0, z: 20)

let cameraOrbit = SCNNode()
scene.rootNode.addChildNode(cameraOrbit)

cameraOrbit.addChildNode(cameraNode)

// MARK: - Spheres

func addSphere(x: Float, y: Float, z: Float, radius: Float, color: UIColor = UIColor.gray) {
    let material = SCNMaterial()
    material.diffuse.contents = color
    
    let sphereGeometry = SCNSphere(radius: CGFloat(radius))
    sphereGeometry.firstMaterial = material
    
    let sphereNode = SCNNode(geometry: sphereGeometry)
    sphereNode.name = "dot"

    sphereNode.position = SCNVector3(x: x, y: y, z: z)

    scene.rootNode.addChildNode(sphereNode)
}

let spacing: Float = 2.0
let radius: Float = 1.0

addSphere(
    x: 0.0,
    y: 0.0,
    z: 0.0,
    radius: radius)
addSphere(
    x: -2.0 * spacing,
    y: -2.0 * spacing,
    z: 0.0,
    radius: radius)
addSphere(
    x: 2.0 * spacing,
    y: 2.0 * spacing,
    z: 0.0,
    radius: radius)
addSphere(
    x: -2.0 * spacing,
    y: 2.0 * spacing,
    z: 0.0,
    radius: radius)
addSphere(
    x: 2.0 * spacing,
    y: -2.0 * spacing,
    z: 0.0,
    radius: radius)
addSphere(
    x: 0.0,
    y: -2.0 * spacing,
    z: -2.0 * spacing,
    radius: radius)
addSphere(
    x: 0.0,
    y: 2.0 * spacing,
    z: 2.0 * spacing,
    radius: radius)
addSphere(
    x: 0.0,
    y: 2.0 * spacing,
    z: -2.0 * spacing,
    radius: radius)
addSphere(
    x: 0.0,
    y: -2.0 * spacing,
    z: 2.0 * spacing,
    radius: radius)
// sphere off center from square
addSphere(
    x: 6.0,
    y: 6.0,
    z: 6.0,
    radius: radius)

// MARK: - Coordinate Symbol

let coordinates = SCNNode()
scene.rootNode.addChildNode(coordinates)

let coordVertices: [SCNVector3] = [
    SCNVector3(0, 0, 0),
    SCNVector3(5, 0, 0),
    SCNVector3(0, 0, 5),
    SCNVector3(-5, 0, 0),
    SCNVector3(0, 0, -5),
    SCNVector3(0, 5, 0)
]
    
let coordColors: [String: UIColor] = [
    "red": UIColor.red,
    "blue": UIColor.blue,
    "green": UIColor.green,
]

var materials: [String : SCNMaterial] {
    var mat = [String : SCNMaterial]()
    
    for (key, value) in coordColors {
        let material = SCNMaterial()
        material.lightingModel = SCNMaterial.LightingModel.constant
        material.isDoubleSided = true
        material.diffuse.contents = value
        
        mat[key] = material
    }
    
    return mat
}

func buildLine(vertice1: SCNVector3, Vertice2: SCNVector3, material: SCNMaterial) -> SCNNode {
    let geometry = SCNGeometry(
        sources: [SCNGeometrySource(vertices: [vertice1, Vertice2])],
        elements: [SCNGeometryElement(indices: [Int32]([0,1]), primitiveType: .line)]
    )
    geometry.firstMaterial = material
    
    return SCNNode(geometry: geometry)
}

coordinates.addChildNode(buildLine(vertice1: coordVertices[1], Vertice2: coordVertices[3], material: materials["red"]!))
coordinates.addChildNode(buildLine(vertice1: coordVertices[2], Vertice2: coordVertices[4], material: materials["blue"]!))
coordinates.addChildNode(buildLine(vertice1: coordVertices[0], Vertice2: coordVertices[5], material: materials["green"]!))

// MARK: - Handle Gesture

var lastWidthRatio: Float = 0
var lastHeightRatio: Float = 0

extension SCNView {
    @objc func handlePanGesture(_ sender: UIPanGestureRecognizer) {
        let translation = sender.translation(in: sender.view)
        let widthRatio = Float(translation.x) / Float(sender.view!.frame.size.width) + lastWidthRatio
        let heightRatio = Float(translation.y) / Float(sender.view!.frame.size.height) + lastHeightRatio
        
        cameraOrbit.eulerAngles.y = Float(-2 * Double.pi) * widthRatio
        cameraOrbit.eulerAngles.x = Float(-Double.pi) * heightRatio

        if (sender.state == .ended) {
            lastWidthRatio = widthRatio.truncatingRemainder(dividingBy: 1)
            lastHeightRatio = heightRatio.truncatingRemainder(dividingBy: 1)
        }
    }
}

// add a tap gesture recognizer
let gesture = UIPanGestureRecognizer(
    target: sceneView,
    action: #selector(sceneView.handlePanGesture(_:)) as Selector
)
sceneView.addGestureRecognizer(gesture)