Augmented reality has come a long way in recent years, and now it’s easier than ever to build your own AR apps. I’ve been tinkering with ARCore and Unity lately, and let me tell you, it’s been a blast! If you’re curious about creating immersive AR experiences for mobile devices, you’ve come to the right place.

Let’s start with the basics. ARCore is Google’s platform for building augmented reality experiences, while Unity is a powerful game engine that’s perfect for creating 3D content. Together, they make a formidable duo for developing AR apps.

First things first, you’ll need to set up your development environment. Make sure you have the latest version of Unity installed, along with the ARCore SDK for Unity. You’ll also want to grab the Android SDK and NDK if you’re targeting Android devices.

Once you’ve got everything installed, fire up Unity and create a new 3D project. The first thing you’ll want to do is import the ARCore SDK. Go to Assets > Import Package > Custom Package and select the ARCore SDK package you downloaded earlier.

Now, let’s set up our AR scene. Create a new scene and add an AR Session and AR Session Origin to your hierarchy. These components are essential for handling AR tracking and positioning.

Here’s a quick example of how to set up your AR session in code:

using UnityEngine;
using UnityEngine.XR.ARFoundation;

public class ARSessionManager : MonoBehaviour
{
    private ARSession arSession;

    void Start()
    {
        arSession = FindObjectOfType<ARSession>();
        if (arSession == null)
        {
            Debug.LogError("ARSession not found in the scene!");
            return;
        }

        arSession.enabled = true;
    }
}

With the AR session set up, we can start adding some cool features to our app. One of the most common AR functionalities is plane detection. This allows your app to recognize flat surfaces in the real world, which you can use to place virtual objects.

To enable plane detection, add an AR Plane Manager component to your AR Session Origin. Then, you can create a script to instantiate objects on detected planes:

using UnityEngine;
using UnityEngine.XR.ARFoundation;
using UnityEngine.XR.ARSubsystems;

public class PlaceObjectsOnPlane : MonoBehaviour
{
    public GameObject objectToPlace;
    private ARRaycastManager arRaycastManager;
    private static List<ARRaycastHit> hits = new List<ARRaycastHit>();

    void Start()
    {
        arRaycastManager = FindObjectOfType<ARRaycastManager>();
    }

    void Update()
    {
        if (Input.touchCount > 0)
        {
            Touch touch = Input.GetTouch(0);

            if (touch.phase == TouchPhase.Began)
            {
                if (arRaycastManager.Raycast(touch.position, hits, TrackableType.PlaneWithinPolygon))
                {
                    Pose hitPose = hits[0].pose;
                    Instantiate(objectToPlace, hitPose.position, hitPose.rotation);
                }
            }
        }
    }
}

This script will instantiate your chosen object wherever the user taps on a detected plane. Pretty cool, right?

Now, let’s talk about image tracking. This feature allows your app to recognize and track specific images in the real world. It’s perfect for creating interactive posters, business cards, or even AR-enhanced board games.

To set up image tracking, you’ll need to add an AR Tracked Image Manager to your scene. Then, create a reference image library with the images you want to track. Here’s a simple script to handle image tracking:

using UnityEngine;
using UnityEngine.XR.ARFoundation;

public class ImageTracker : MonoBehaviour
{
    public GameObject[] arObjectsToPlace;
    private ARTrackedImageManager arTrackedImageManager;

    void Awake()
    {
        arTrackedImageManager = FindObjectOfType<ARTrackedImageManager>();
    }

    void OnEnable()
    {
        arTrackedImageManager.trackedImagesChanged += OnTrackedImagesChanged;
    }

    void OnDisable()
    {
        arTrackedImageManager.trackedImagesChanged -= OnTrackedImagesChanged;
    }

    void OnTrackedImagesChanged(ARTrackedImagesChangedEventArgs eventArgs)
    {
        foreach (var trackedImage in eventArgs.added)
        {
            UpdateImage(trackedImage);
        }
        foreach (var trackedImage in eventArgs.updated)
        {
            UpdateImage(trackedImage);
        }
    }

    void UpdateImage(ARTrackedImage trackedImage)
    {
        string imageName = trackedImage.referenceImage.name;
        Vector3 position = trackedImage.transform.position;

        GameObject prefab = arObjectsToPlace[0];
        foreach (GameObject go in arObjectsToPlace)
        {
            if (go.name == imageName)
            {
                prefab = go;
                break;
            }
        }
        GameObject newObject = Instantiate(prefab, position, Quaternion.identity);
        newObject.transform.parent = trackedImage.transform;
    }
}

This script will instantiate a corresponding 3D object whenever a tracked image is detected. You can easily expand on this to create more complex interactions.

One of the coolest features of ARCore is light estimation. This allows your virtual objects to blend more realistically with the real world by adjusting their lighting based on the environment. Here’s a simple shader that uses ARCore’s light estimation:

Shader "Custom/ARLightEstimation"
{
    Properties
    {
        _MainTex ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }
        LOD 100

        CGPROGRAM
        #pragma surface surf Lambert

        sampler2D _MainTex;
        float4 _GlobalLightEstimation;

        struct Input
        {
            float2 uv_MainTex;
        };

        void surf (Input IN, inout SurfaceOutput o)
        {
            fixed4 c = tex2D (_MainTex, IN.uv_MainTex);
            o.Albedo = c.rgb * _GlobalLightEstimation.rgb;
            o.Alpha = c.a;
        }
        ENDCG
    }
    FallBack "Diffuse"
}

To use this shader, you’ll need to update the _GlobalLightEstimation value in your script based on ARCore’s light estimation data.

As you dive deeper into AR development, you’ll discover many more exciting features and possibilities. Face tracking, for instance, opens up a whole new world of AR experiences. Imagine creating fun filters or even virtual makeup try-on apps!

Here’s a quick example of how to set up face tracking:

using UnityEngine;
using UnityEngine.XR.ARFoundation;

public class FaceTracker : MonoBehaviour
{
    public GameObject faceMeshPrefab;
    private ARFaceManager arFaceManager;

    void Start()
    {
        arFaceManager = FindObjectOfType<ARFaceManager>();
        arFaceManager.facesChanged += OnFacesChanged;
    }

    void OnFacesChanged(ARFacesChangedEventArgs args)
    {
        foreach (var face in args.added)
        {
            GameObject faceGameObject = Instantiate(faceMeshPrefab, face.transform);
            faceGameObject.GetComponent<MeshRenderer>().material.mainTexture = face.GetComponent<ARFaceMeshVisualizer>().mesh.texture;
        }
    }
}

This script will instantiate a face mesh prefab for each detected face, allowing you to overlay 3D objects or effects onto the user’s face.

As you can see, building AR apps with ARCore and Unity is an exciting journey full of possibilities. From placing virtual objects in the real world to creating interactive experiences with image tracking and face filters, the sky’s the limit!

Remember, the key to creating great AR experiences is to think about how you can enhance the real world in meaningful ways. Don’t just add 3D objects for the sake of it – think about how AR can solve problems or create unique experiences that wouldn’t be possible otherwise.

As you continue to explore AR development, you’ll encounter challenges like optimizing performance, handling different lighting conditions, and creating intuitive user interfaces for AR. But don’t let that discourage you – with each challenge comes an opportunity to learn and grow as a developer.

So, what are you waiting for? Fire up Unity, grab the ARCore SDK, and start building your own augmented reality experiences. Who knows? Your next AR app might just change the way we interact with the world around us. Happy coding!