Jetpack Compose and AR Integration

Augmented Reality (AR) is transforming how users interact with digital content by overlaying computer-generated images onto the real world. Integrating AR into Android applications using Jetpack Compose, the modern UI toolkit, offers exciting possibilities. While Jetpack Compose is primarily designed for building declarative UI, it can be combined effectively with ARCore, Google’s platform for building AR experiences.

Understanding the Basics

What is Augmented Reality (AR)?

Augmented Reality (AR) is a technology that superimposes a computer-generated image on a user’s view of the real world, providing a composite view. It enhances the real world with digital content, such as images, animations, and 3D models.

What is ARCore?

ARCore is Google’s platform for building augmented reality experiences. It uses three key technologies:

• Motion Tracking: Allows the phone to understand and track its position relative to the world.
• Environmental Understanding: Enables the phone to detect the size and location of horizontal surfaces like tables and floors.
• Light Estimation: Allows the phone to estimate the environment’s current lighting conditions.

What is Jetpack Compose?

Jetpack Compose is Android’s modern UI toolkit for building native UI. It simplifies and accelerates UI development with less code, powerful tools, and intuitive Kotlin APIs.

Why Combine Jetpack Compose and ARCore?

• Modern UI: Use Compose for creating interactive and dynamic UI elements within AR scenes.
• Enhanced User Experience: Seamlessly blend digital content with the real world, enhancing user engagement.
• Declarative Approach: Build and manage UI elements with Compose’s declarative syntax.
• Integration Capabilities: Combine Compose UI components with ARCore’s scene rendering.

How to Integrate Jetpack Compose with ARCore

The integration process involves creating an ARCore scene and overlaying Compose UI elements on top of it. Here’s a detailed guide on how to achieve this:

Step 1: Set Up Your Project

First, create a new Android project in Android Studio or open an existing one. Ensure you have the necessary dependencies and ARCore SDK set up.

1.1 Add ARCore Dependency

Add the ARCore dependency in your build.gradle (Module: app) file:

dependencies {
    implementation "com.google.ar:core:1.41.0"
}

1.2 Configure Camera Permissions

Add camera permission to your AndroidManifest.xml file:

<uses-permission android:name="android.permission.CAMERA"/>

<!-- Indicates that this app requires ARCore. Google Play Store will prevent the app from being
     installed on devices without ARCore (min. OpenGL ES version 3.0).-->
<uses-feature android:name="android.hardware.camera.ar" android:required="true" />

<application ...>
    <meta-data
        android:name="com.google.ar.core"
        android:value="required" />
</application>

Step 2: Create an ARCore Session

Initialize the ARCore session in your Activity. This session is essential for AR tracking and rendering.

import android.opengl.GLSurfaceView
import android.os.Bundle
import androidx.activity.ComponentActivity

class ARActivity : ComponentActivity() {
    private lateinit var surfaceView: GLSurfaceView
    private var arSession: com.google.ar.core.Session? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        // Check AR Support and Install if needed.
        if (com.google.ar.core.ArCoreApk.getInstance().checkAvailability(this) == com.google.ar.core.ArCoreApk.Availability.UNSUPPORTED_DEVICE_NOT_CAPABLE) {
             //finish()
        }
        
        var installRequested = false
        when (com.google.ar.core.ArCoreApk.getInstance().requestInstall(this, !installRequested)) {
            com.google.ar.core.ArCoreApk.InstallStatus.INSTALL_REQUESTED -> {
                 installRequested = true
                 return
            }
            com.google.ar.core.ArCoreApk.InstallStatus.INSTALLED -> {
            }
        }
         
        // Initialize AR session
        try {
            arSession = com.google.ar.core.Session(this)
        } catch (e: Exception) {
            // Handle session creation errors
        }

        surfaceView = GLSurfaceView(this)
        setContentView(surfaceView)
    }

    override fun onResume() {
        super.onResume()
        try {
            arSession?.resume()
        } catch (e: Exception) {
            // Handle session resume errors
        }
        surfaceView.onResume()
    }

    override fun onPause() {
        super.onPause()
        surfaceView.onPause()
        arSession?.pause()
    }
}

Step 3: Render the AR Scene

Set up a renderer to draw the AR scene. This typically involves creating a custom Renderer class that handles OpenGL ES drawing using ARCore data.

import android.opengl.GLES20
import android.opengl.GLSurfaceView
import com.google.ar.core.Frame
import javax.microedition.khronos.egl.EGLConfig
import javax.microedition.khronos.opengles.GL10

class ARRenderer(private val arSession: com.google.ar.core.Session?) : GLSurfaceView.Renderer {

    override fun onSurfaceCreated(gl: GL10?, config: EGLConfig?) {
        GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f)
    }

    override fun onSurfaceChanged(gl: GL10?, width: Int, height: Int) {
        GLES20.glViewport(0, 0, width, height)
    }

    override fun onDrawFrame(gl: GL10?) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT or GLES20.GL_DEPTH_BUFFER_BIT)

        try {
            arSession?.update()
            val frame: Frame? = arSession?.currentFrame

            // Process ARCore frame to render the scene
            // Example: drawing detected planes, anchors, etc.

        } catch (e: Exception) {
            // Handle frame processing errors
        }
    }
}

Set the renderer for your GLSurfaceView:

surfaceView.setRenderer(ARRenderer(arSession))
surfaceView.renderMode = GLSurfaceView.RENDERMODE_CONTINUOUSLY

Step 4: Overlay Compose UI

To overlay Jetpack Compose UI elements on top of the AR scene, you can use AndroidView within Compose to embed the GLSurfaceView and then overlay other Compose elements on top of it.

import androidx.compose.runtime.Composable
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.viewinterop.AndroidView
import androidx.compose.foundation.layout.*
import androidx.compose.material.Text
import androidx.compose.ui.Modifier
import androidx.compose.ui.unit.dp
import androidx.compose.ui.Alignment

@Composable
fun ARComposeIntegration() {
    Box(modifier = Modifier.fillMaxSize()) {
        // Embed the AR Surface View
        AndroidView(
            factory = { context ->
                GLSurfaceView(context).apply {
                    setRenderer(ARRenderer(arSession))
                    renderMode = GLSurfaceView.RENDERMODE_CONTINUOUSLY
                }
            },
            modifier = Modifier.fillMaxSize()
        )

        // Overlay Compose UI Elements
        Column(
            modifier = Modifier
                .align(Alignment.TopCenter)
                .padding(16.dp)
        ) {
            Text("AR Content Overlay with Compose")
            // Add more Compose UI elements as needed
        }
    }
}

@Preview(showBackground = true)
@Composable
fun ARComposeIntegrationPreview() {
    ARComposeIntegration()
}

To use this composable in the ARActivity, set the content view using setContent:

import androidx.activity.compose.setContent
class ARActivity : ComponentActivity() {
    // ... Existing code ...
        
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            ARComposeIntegration()
        }
    }
    // ... Existing code ...
}

Step 5: Interact with ARCore Data

To create interactive AR experiences, pass ARCore data to your Compose UI elements. For example, you can display information about detected planes or anchors in a Compose Text element.

// Inside ARRenderer, capture AR data:
override fun onDrawFrame(gl: GL10?) {
    // ... existing code ...
    val frame: Frame? = arSession?.currentFrame
    val planes = arSession?.getAllTrackables(com.google.ar.core.Plane::class.java)

    // Update a LiveData or mutable state with this data
    // For example, create a MutableState in your activity or ViewModel:
    // val arDataState = mutableStateOf(planes)

    // You will need a way to update Compose from the ARRenderer. A proper architecture using
    // callbacks, LiveData, or State is necessary.
}

// Then, in your Compose function:
@Composable
fun ARComposeIntegration(arData: List?) {
    Box(modifier = Modifier.fillMaxSize()) {
        // ... existing code ...

        Column(
            modifier = Modifier
                .align(Alignment.BottomCenter)
                .padding(16.dp)
        ) {
            Text("Detected Planes: ${arData?.size ?: 0}")
        }
    }
}

Best Practices and Considerations

• Performance: AR applications can be resource-intensive. Optimize your OpenGL rendering and Compose UI to ensure smooth performance.
• Lifecycle Management: Properly manage the ARCore session lifecycle to avoid memory leaks and ensure stability.
• UI/UX Design: Design your UI elements to complement the AR experience, providing useful information without obstructing the view.
• Testing: Test your AR application on various devices to ensure compatibility and consistent performance.

Conclusion

Integrating Jetpack Compose with ARCore enables you to create innovative and immersive Android applications. By combining Compose’s modern UI capabilities with ARCore’s powerful AR features, you can deliver compelling user experiences that blend the digital and physical worlds. While this integration requires careful management of OpenGL and Compose interoperability, the resulting applications can offer unique value and engagement for users.