An ARKit Placement Square

ViewController.swift

//
//  ViewController.swift
//
//  Created by Oscar De la Hera Gomez on 8/13/18.
//  Copyright © 2018 Delasign. All rights reserved.


import UIKit
import SceneKit
import ARKit

class ViewController: UIViewController, ARSCNViewDelegate {

    @IBOutlet var sceneView: ARSCNView!
    var positioningPlaneNode:SCNNode = SCNNode();
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        screenWidth = self.view.frame.width;
        screenHeight = self.view.frame.height;
        
        // Set the view's delegate
        sceneView.delegate = self
        
        // Show statistics such as fps and timing information
        sceneView.showsStatistics = true
        
        sceneView.debugOptions = [ARSCNDebugOptions.showFeaturePoints] //, ARSCNDebugOptions.showWorldOrigin]
        
        // CREATE OUT PLANE FOR THE MARKER
        
        // 1 CREATE A PLANE
        let plane = SCNPlane(width: 0.1, height: 0.1);
        
        // 2 SET IT TO BE TRANSPARENT - WE WILL CHANGE THIS WHEN ITS RESET
        plane.materials.first?.diffuse.contents = UIColor.white.withAlphaComponent(0);
        
        // 3 ADD THE PLANE TO THE NODE
        self.positioningPlaneNode = SCNNode(geometry: plane);
        
        // 4 SET AN INITIAL POSITION, AND A ROTIATION TO REFERENCE A HORIZONTAL PLANE
        self.positioningPlaneNode.position = SCNVector3(0,0,0);
        self.positioningPlaneNode.eulerAngles.x = -.pi / 2
        
        // 5 ADD THE NODE TO THE SCENE
        self.sceneView.scene.rootNode.addChildNode(self.positioningPlaneNode);
        
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        // Create a session configuration
        let configuration = ARWorldTrackingConfiguration()
        configuration.planeDetection = .horizontal;

        // Run the view's session
        sceneView.session.run(configuration)
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        
        // Pause the view's session
        sceneView.session.pause()
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Release any cached data, images, etc that aren't in use.
    }

    // MARK: - ARSCNViewDelegate
    
/*
    // Override to create and configure nodes for anchors added to the view's session.
    func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
        let node = SCNNode()
     
        return node
    }
*/
    
    func session(_ session: ARSession, didFailWithError error: Error) {
        // Present an error message to the user
        
    }
    
    func sessionWasInterrupted(_ session: ARSession) {
        // Inform the user that the session has been interrupted, for example, by presenting an overlay
        
    }
    
    func sessionInterruptionEnded(_ session: ARSession) {
        // Reset tracking and/or remove existing anchors if consistent tracking is required
        
    }
    
    
    // MARK : ARKIT RENDERER
    
    func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {

    }
    
    func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
        

    }
    
    func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
        
        // PERFORM A HIT TEST
//        let centerOfScreen:CGPoint = CGPoint(x: screenWidth/2, y: screenHeight/2);
        let centerOfScreen:CGPoint = CGPoint(x: 0.5, y: 0.5);
        let currentFrame:ARFrame? = self.sceneView.session.currentFrame;
        
        guard currentFrame != nil else {
            return
        }
        
        let results:[ARHitTestResult] = currentFrame!.hitTest(centerOfScreen, types: [.estimatedHorizontalPlane, .featurePoint]);
        
        if results.count < 1 {
            return;
        }
        else {
          // USE THE HITTEST TO CHANGE THE POSITION OF THE PLANE.
            let firstResult:ARHitTestResult = results.first!;
            print(firstResult);
            
            self.positioningPlaneNode.position = SCNVector3Make(
                firstResult.worldTransform.columns.3.x,
                firstResult.worldTransform.columns.3.y,
                firstResult.worldTransform.columns.3.z
            );
            
//            self.positioningPlaneNode.rotation = firstResult.worldTransform
            
            self.positioningPlaneNode.geometry!.materials.first?.diffuse.contents = UIColor.white.withAlphaComponent(0.5);
        }
        
    }
}