Building Augmented Reality Experiences with Flutter and ARCore

Augmented Reality (AR) has revolutionized how users interact with digital content, seamlessly blending virtual elements with the real world. Flutter, with its cross-platform capabilities and rich widget library, paired with ARCore, Google’s platform for building augmented reality experiences, offers developers a robust toolset for creating immersive AR applications. This post will guide you through the process of building AR experiences using Flutter and ARCore, including setting up the environment, implementing AR features, and handling user interactions.

What is Augmented Reality (AR)?

Augmented Reality (AR) overlays digital content onto the real-world environment, creating interactive experiences that enhance the user’s perception. Unlike Virtual Reality (VR), which immerses the user entirely in a virtual environment, AR enriches the existing environment.

Why Flutter and ARCore?

• Cross-Platform: Flutter allows you to write code once and deploy it on both Android and iOS platforms.
• ARCore Integration: ARCore provides the necessary tools to track the environment, understand surfaces, and estimate lighting, making it easy to integrate AR features into Flutter applications.
• Rich UI: Flutter’s declarative UI paradigm simplifies the process of building complex and interactive AR interfaces.

Setting Up the Development Environment

Step 1: Install Flutter

Ensure you have Flutter installed and configured on your machine. If not, follow the official Flutter installation guide:

Flutter Installation Guide

Step 2: Install ARCore SDK

ARCore requires the ARCore SDK, which is usually bundled in Flutter plugins. However, ensure your development device supports ARCore:

ARCore Supported Devices

Step 3: Create a New Flutter Project

Create a new Flutter project using the following command:

flutter create ar_flutter_app
cd ar_flutter_app

Step 4: Add Flutter ARCore Plugin

There are several Flutter packages available for ARCore. One popular choice is arcore_flutter_plugin. Add it to your pubspec.yaml file:

dependencies:
  flutter:
    sdk: flutter
  arcore_flutter_plugin: ^0.0.7 # Check for the latest version

Then, run:

flutter pub get

Implementing AR Features in Flutter

Step 1: Setting Up the AR View

Import the necessary packages and create an ARCoreView widget:

import 'package:flutter/material.dart';
import 'package:arcore_flutter_plugin/arcore_flutter_plugin.dart';
import 'dart:async';

void main() {
  runApp(MaterialApp(home: ARScreen()));
}

class ARScreen extends StatefulWidget {
  @override
  _ARScreenState createState() => _ARScreenState();
}

class _ARScreenState extends State {
  late ArCoreController arCoreController;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter ARCore'),
      ),
      body: ArCoreView(
        onArCoreViewCreated: _onArCoreViewCreated,
      ),
    );
  }

  void _onArCoreViewCreated(ArCoreController controller) {
    arCoreController = controller;
    arCoreController.onPlaneDetected = _handleOnPlaneDetected;
  }

  void _handleOnPlaneDetected(ArCorePlane plane) {
    // Handle plane detection event
  }

  @override
  void dispose() {
    arCoreController.dispose();
    super.dispose();
  }
}

Step 2: Handling Plane Detection

Implement the _handleOnPlaneDetected function to respond when ARCore detects a plane in the environment. For example, you can place a 3D object on the detected plane:

import 'package:flutter/material.dart';
import 'package:arcore_flutter_plugin/arcore_flutter_plugin.dart';
import 'package:vector_math/vector_math_64.dart' as vector;

class ARScreen extends StatefulWidget {
  @override
  _ARScreenState createState() => _ARScreenState();
}

class _ARScreenState extends State {
  late ArCoreController arCoreController;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter ARCore'),
      ),
      body: ArCoreView(
        onArCoreViewCreated: _onArCoreViewCreated,
      ),
    );
  }

  void _onArCoreViewCreated(ArCoreController controller) {
    arCoreController = controller;
    arCoreController.onPlaneDetected = _handleOnPlaneDetected;
  }

  void _handleOnPlaneDetected(ArCorePlane plane) {
    if (mounted) {
      _addCube(plane);
    }
  }

  void _addCube(ArCorePlane plane) {
    final material = ArCoreMaterial(
      color: Colors.red,
    );

    final cube = ArCoreCube(
      materials: [material],
      size: vector.Vector3(0.1, 0.1, 0.1),
    );

    final node = ArCoreNode(
      shape: cube,
      position: plane.centerPose.translation,
      rotation: plane.centerPose.rotation,
    );

    arCoreController.addArCoreNodeWithAnchor(node);
  }

  @override
  void dispose() {
    arCoreController.dispose();
    super.dispose();
  }
}

In this example, a red cube is added to the scene whenever a plane is detected.

Step 3: Adding 3D Models

To add more complex 3D models, you can use the ArCoreReferenceNode. Ensure the model (e.g., a .sfb file) is in your assets folder and is included in your pubspec.yaml:

assets:
  - assets/my_model.sfb

Then, use the ArCoreReferenceNode:

import 'package:flutter/material.dart';
import 'package:arcore_flutter_plugin/arcore_flutter_plugin.dart';
import 'package:flutter/services.dart';
import 'dart:async';

class ARScreen extends StatefulWidget {
  @override
  _ARScreenState createState() => _ARScreenState();
}

class _ARScreenState extends State {
  late ArCoreController arCoreController;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter ARCore'),
      ),
      body: ArCoreView(
        onArCoreViewCreated: _onArCoreViewCreated,
        enableTapRecognizer: true,
      ),
    );
  }

  void _onArCoreViewCreated(ArCoreController controller) {
    arCoreController = controller;
    arCoreController.onPlaneDetected = _handleOnPlaneDetected;
    arCoreController.onNodeTap = (name) {
      print('Tapped on node: $name');
    };
  }

  void _handleOnPlaneDetected(ArCorePlane plane) {
    _addModel(plane);
  }

  Future _addModel(ArCorePlane plane) async {
    final ByteData bytes = await rootBundle.load('assets/my_model.sfb');

    final node = ArCoreReferenceNode(
      name: 'my_model',
      object3DFileName: 'assets/my_model.sfb',
      bytes: bytes.buffer.asUint8List(),
      position: plane.centerPose.translation,
      rotation: plane.centerPose.rotation,
    );

    arCoreController.addArCoreNodeWithAnchor(node);
  }

  @override
  void dispose() {
    arCoreController.dispose();
    super.dispose();
  }
}

In this example, my_model.sfb is loaded and placed on the detected plane.

Handling User Interactions

Gesture Recognition

Flutter allows you to integrate gesture recognizers with your AR elements, allowing users to interact with the augmented content. Common gestures include tapping, panning, and scaling.

Enable tap recognizer:

ArCoreView(
    onArCoreViewCreated: _onArCoreViewCreated,
    enableTapRecognizer: true,
)

Handle tap events:

arCoreController.onNodeTap = (name) {
  print('Tapped on node: $name');
};

Conclusion

Combining Flutter and ARCore offers a compelling way to build augmented reality experiences that are cross-platform and interactive. By following the steps outlined in this guide, you can set up your development environment, implement AR features such as plane detection and 3D object placement, and handle user interactions. As AR technology continues to evolve, Flutter and ARCore provide a robust framework for developers to create innovative and immersive applications that bridge the gap between the physical and digital worlds.