<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.arsnapchat">

    <uses-feature
        android:name="android.hardware.camera"
        android:required="true" />

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

    <uses-feature
        android:name="android.hardware.camera.ar"
        android:required="true" />
    <uses-feature android:name="android.hardware.camera.autofocus" />

    <uses-feature
        android:glEsVersion="0x00020000"
        android:required="true" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <meta-data
            android:name="com.google.ar.core"
            android:value="required" />
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <fragment
        android:id="@+id/arFragment"
        android:name="com.example.arsnapchat.CustomArFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import androidx.annotation.Nullable;
import com.google.ar.core.Config;
import com.google.ar.core.Session;
import com.google.ar.sceneform.ux.ArFragment;
import java.util.EnumSet;
import java.util.Set;

public class CustomArFragment extends ArFragment {
    @Override
    protected Config getSessionConfiguration(Session session) {
        Config config = new Config(session);

        // Configure 3D Face Mesh
        config.setAugmentedFaceMode(Config.AugmentedFaceMode.MESH3D);
        this.getArSceneView().setupSession(session);
        return config;
    }

    @Override
    protected Set<Session.Feature> getSessionFeatures() {
        // Configure Front Camera
        return EnumSet.of(Session.Feature.FRONT_CAMERA);
    }

    // Override to turn off planeDiscoveryController.
    // Plane traceable are not supported with the front camera.
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        FrameLayout frameLayout = (FrameLayout) super.onCreateView(inflater, container, savedInstanceState);
        getPlaneDiscoveryController().hide();
        getPlaneDiscoveryController().setInstructionView(null);
        return frameLayout;
    }
}

import android.os.Bundle;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import com.google.ar.core.AugmentedFace;
import com.google.ar.core.Frame;
import com.google.ar.core.TrackingState;
import com.google.ar.sceneform.rendering.ModelRenderable;
import com.google.ar.sceneform.rendering.Renderable;
import com.google.ar.sceneform.rendering.Texture;
import com.google.ar.sceneform.ux.AugmentedFaceNode;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
    private ModelRenderable modelRenderable;
    private Texture texture;
    private boolean isAdded = false;
    private final HashMap<AugmentedFace, AugmentedFaceNode> faceNodeMap = new HashMap<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        CustomArFragment customArFragment = (CustomArFragment) getSupportFragmentManager().findFragmentById(R.id.arFragment);

        // Use ModelRenderable.Builder to load the *.sfb
        // models at runtime.
        // Load the face regions renderable.
        // To ensure that the asset doesn't cast or receive
        // shadows in the scene, ensure that setShadowCaster
        // and setShadowReceiver are both set to false.
        ModelRenderable.builder()
                .setSource(this, R.raw.fox_face)
                .build()
                .thenAccept(rendarable -> {
                    this.modelRenderable = rendarable;
                    this.modelRenderable.setShadowCaster(false);
                    this.modelRenderable.setShadowReceiver(false);

                })
                .exceptionally(throwable -> {
                    Toast.makeText(this, "error loading model", Toast.LENGTH_SHORT).show();
                    return null;
                });

        // Load the face mesh texture.(2D texture on face)
        // Save the texture(.png file) in drawable folder.
        Texture.builder()
                .setSource(this, R.drawable.fox_face_mesh_texture)
                .build()
                .thenAccept(textureModel -> this.texture = textureModel)
                .exceptionally(throwable -> {
                    Toast.makeText(this, "cannot load texture", Toast.LENGTH_SHORT).show();
                    return null;
                });

        assert customArFragment != null;

        // This is important to make sure that the camera
        // stream renders first so that the face mesh
        // occlusion works correctly.
        customArFragment.getArSceneView().setCameraStreamRenderPriority(Renderable.RENDER_PRIORITY_FIRST);
        customArFragment.getArSceneView().getScene().addOnUpdateListener(frameTime -> {
            if (modelRenderable == null || texture == null) {
                return;
            }
            Frame frame = customArFragment.getArSceneView().getArFrame();
            assert frame != null;

            // Render the effect for the face Rendering the effect involves these steps:
            // 1.Create the Sceneform face node.
            // 2.Add the face node to the Sceneform scene.
            // 3.Set the face region Renderable. Extracting the face mesh and
            // rendering the face effect is added to a listener on
            // the scene that gets called on every processed camera frame.
            Collection<AugmentedFace> augmentedFaces = frame.getUpdatedTrackables(AugmentedFace.class);

            // Make new AugmentedFaceNodes for any new faces.
            for (AugmentedFace augmentedFace : augmentedFaces) {
                if (isAdded) return;

                AugmentedFaceNode augmentedFaceMode = new AugmentedFaceNode(augmentedFace);
                augmentedFaceMode.setParent(customArFragment.getArSceneView().getScene());
                augmentedFaceMode.setFaceRegionsRenderable(modelRenderable);
                augmentedFaceMode.setFaceMeshTexture(texture);
                faceNodeMap.put(augmentedFace, augmentedFaceMode);
                isAdded = true;

                // Remove any AugmentedFaceNodes associated with
                // an AugmentedFace that stopped tracking.
                Iterator<Map.Entry<AugmentedFace, AugmentedFaceNode>> iterator = faceNodeMap.entrySet().iterator();
                Map.Entry<AugmentedFace, AugmentedFaceNode> entry = iterator.next();
                AugmentedFace face = entry.getKey();
                while (face.getTrackingState() == TrackingState.STOPPED) {
                    AugmentedFaceNode node = entry.getValue();
                    node.setParent(null);
                    iterator.remove();
                }
            }
        });
    }
}