Surface plane detection

Description

We will detect both horizontal and vertical surfaces.

Once detected, we will highlight the detected horizontal and vertical surfaces.

Surface detection is important as floors and walls dictate the limits of our surroundings and provide options to interact with them.

Video

Code

using ARKit;
using Foundation;
using SceneKit;
using System;
using System.Collections.Generic;
using UIKit;

namespace XamarinArkitSample
{
    public partial class ViewController : UIViewController
    {
        private readonly ARSCNView sceneView;

        public ViewController(IntPtr handle) : base(handle)
        {
            this.sceneView = new ARSCNView
            {
                AutoenablesDefaultLighting = true,
                DebugOptions = ARSCNDebugOptions.ShowFeaturePoints
                | ARSCNDebugOptions.ShowWorldOrigin,
                Delegate = new SceneViewDelegate()
            };

            this.View.AddSubview(this.sceneView);
        }

        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            this.sceneView.Frame = this.View.Frame;
        }

        public override void ViewDidAppear(bool animated)
        {
            base.ViewDidAppear(animated);

            this.sceneView.Session.Run(new ARWorldTrackingConfiguration
            {
                AutoFocusEnabled = true,
                PlaneDetection = ARPlaneDetection.Horizontal | ARPlaneDetection.Vertical,
                LightEstimationEnabled = true,
                WorldAlignment = ARWorldAlignment.GravityAndHeading
            }, ARSessionRunOptions.ResetTracking | ARSessionRunOptions.RemoveExistingAnchors);
        }

        public override void ViewDidDisappear(bool animated)
        {
            base.ViewDidDisappear(animated);

            this.sceneView.Session.Pause();
        }

        public override void DidReceiveMemoryWarning()
        {
            base.DidReceiveMemoryWarning();
        }
    }

    internal class PlaneNode : SCNNode
    {
        private readonly SCNPlane planeGeometry;

        public PlaneNode(ARPlaneAnchor planeAnchor, UIColor colour)
        {
            Geometry = (planeGeometry = CreateGeometry(planeAnchor, colour));
        }

        public void Update(ARPlaneAnchor planeAnchor)
        {
            planeGeometry.Width = planeAnchor.Extent.X;
            planeGeometry.Height = planeAnchor.Extent.Z;

            Position = new SCNVector3(
                planeAnchor.Center.X,
                planeAnchor.Center.Y,
                planeAnchor.Center.Z);
        }

        private static SCNPlane CreateGeometry(ARPlaneAnchor planeAnchor, UIColor colour)
        {
            var material = new SCNMaterial();
            material.Diffuse.Contents = colour;
            material.DoubleSided = true;
            material.Transparency = 0.8f;

            var geometry = SCNPlane.Create(planeAnchor.Extent.X, planeAnchor.Extent.Z);
            geometry.Materials = new[] { material };

            return geometry;
        }
    }

    public class SceneViewDelegate : ARSCNViewDelegate
    {
        private readonly IDictionary<NSUuid, PlaneNode> planeNodes = new Dictionary<NSUuid, PlaneNode>();

        public override void DidAddNode(ISCNSceneRenderer renderer, SCNNode node, ARAnchor anchor)
        {
            if (anchor is ARPlaneAnchor planeAnchor)
            {
                UIColor colour;

                if(planeAnchor.Alignment == ARPlaneAnchorAlignment.Vertical)
                {
                    colour = UIColor.Red;
                }
                else
                {
                    colour = UIColor.Blue;
                }

                var planeNode = new PlaneNode(planeAnchor, colour);
                var angle = (float)(-Math.PI / 2);
                planeNode.EulerAngles = new SCNVector3(angle, 0, 0);

                node.AddChildNode(planeNode);
                this.planeNodes.Add(anchor.Identifier, planeNode);
            }
        }

        public override void DidRemoveNode(ISCNSceneRenderer renderer, SCNNode node, ARAnchor anchor)
        {
            if (anchor is ARPlaneAnchor planeAnchor)
            {
                this.planeNodes[anchor.Identifier].RemoveFromParentNode();
                this.planeNodes.Remove(anchor.Identifier);
            }
        }

        public override void DidUpdateNode(ISCNSceneRenderer renderer, SCNNode node, ARAnchor anchor)
        {
            if (anchor is ARPlaneAnchor planeAnchor)
            {
                this.planeNodes[anchor.Identifier].Update(planeAnchor);
            }
        }
    }
}