How to draw a line between two points in SceneKit (eulerAngle and quaternion)

README.md

Refarence

• EulerAngles

  • How to draw a line between two points in SceneKit?

• Quaternion

  • Draw SceneKit object between two points
  • Finding quaternion representing the rotation from one vector to another

SceneKitViewController.swift

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport
import SceneKit

class MyViewController : UIViewController {
        
    override func loadView() {
        
        let scnView = SCNView()
        scnView.delegate = self as? SCNSceneRendererDelegate
        scnView.isPlaying = true
        
        let scene = SCNScene()
        scnView.backgroundColor = UIColor.gray

        scnView.allowsCameraControl = true
        scnView.scene = scene
        
        let cameraNode = SCNNode()
        cameraNode.camera = SCNCamera()
        cameraNode.position = SCNVector3(x: 0, y: 0, z: 15)
        scene.rootNode.addChildNode(cameraNode)
        
        let from = simd_float3(x: -1, y: 5, z: 0)
        let to = simd_float3(x: 0, y: 0, z: 2)
        
        for pos in [from, to] {
            let sphere = SCNSphere(radius: 0.2)
            let sphereNode = SCNNode(geometry: sphere)
            sphereNode.simdPosition = pos
            scene.rootNode.addChildNode(sphereNode)
        }
        
        let cylinderNode1 = SCNNode(geometry: SCNCylinder())
        scene.rootNode.addChildNode(cylinderNode1)
        eulerAngle(node: cylinderNode1, from: from,to: to)

        let cylinderNode2 = SCNNode(geometry: SCNCylinder())

        let material = SCNMaterial()
        material.diffuse.contents = UIColor.green
        cylinderNode2.geometry?.firstMaterial = material
        scene.rootNode.addChildNode(cylinderNode2)
        quaternion(node: cylinderNode2, from: from,to: to)
        
        self.view = scnView
    }
    
    func eulerAngle(node: SCNNode,
                    from: simd_float3, to: simd_float3){
        
        node.simdPosition = (from + to) / 2
        let distance = simd_distance(from,to)
        let cylinder = node.geometry as! SCNCylinder
        cylinder.radius = 0.2
        cylinder.height = CGFloat(distance)
        
        let eulerAngles
            = simd_float3(Float.pi / 2,
                          acos((to.z-from.z)/distance),
                          atan2((to.y-from.y),(to.x-from.x)))
        
        node.simdEulerAngles = eulerAngles
    }
    
    func quaternion(node: SCNNode,
                    from: simd_float3, to: simd_float3){
        
        node.simdPosition = (from + to) / 2
        let distance = simd_distance(from,to)
        let cylinder = node.geometry as! SCNCylinder
        cylinder.radius = 0.2
        cylinder.height = CGFloat(distance)
        
        let vector = to - from
        let height = simd_length(vector)
        let line_axis = simd_float3(0, height/2, 0)

        let vector_cross = simd_cross(line_axis, vector)
        let qw = simd_length(line_axis) * simd_length(vector) + simd_dot(line_axis, vector)
        let q = simd_quatf(ix: vector_cross.x, iy: vector_cross.y,
                           iz: vector_cross.z, r: qw).normalized
        
        node.simdOrientation = q
    }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()