Model3DViewer is a mobile Android application that demonstrates how to render and manipulate 3D models using a WebView embedded in a Jetpack Compose interface.
This is a Proof of Concept (POC) that combines native Android capabilities with web-based 3D rendering powered by three.js.
Context:
Integrating immersive 3D visualizations in modern Android apps can enhance user interaction and design. This project shows how to embed and control 3D content using three.js inside a native Jetpack Compose app.
Objectives:
- Render 3D models in an Android WebView.
- Enable interaction via touch gestures and sensors.
- Implement reusable Compose screens for various use cases.
- Showcase a bridge between Kotlin and JavaScript.
- Ensure offline rendering by bundling all 3D scripts locally.
- Render 3D models (STL, GLTF, GLB) with three.js inside a WebView.
- Use OrbitControls for touch-based interaction (rotate, zoom).
- Load custom 3D files from device storage.
- Display the 3D model above the UI with a transparent WebView.
- Rotate the model using device sensors (gyroscope, accelerometer, magnetometer).
- Configure lighting and camera through a dynamic bottom sheet.
- Full support for offline mode (no network required).
| Step | Goal | Outcome |
|---|---|---|
| Project Setup | Compose + WebView integration | Jetpack Compose linked with embedded WebView |
| three.js Integration | Render 3D content | Scene loaded using local JS files |
| Model Interaction | OrbitControls + File picker | Custom 3D models loadable from gallery |
| Sensor Control | Real-world rotation support | Model reacts to device orientation |
| Bridge Implementation | Communication Kotlin ⇄ JS | Custom commands via evaluateJavascript() |
| Polish & Documentation | Clean code + visual assets | Screenshots and full README written |
- Language: Kotlin
- UI: Jetpack Compose
- Architecture: MVVM (loosely)
- 3D Rendering: three.js
- Web Integration: Android WebView
- 3D File Support: STL, GLTF, GLB
- Sensor Fusion: Gyroscope, Accelerometer, Magnetometer
- Testing: Manual & Visual (POC stage)
- IDE: Android Studio Giraffe
| Girl 3d model | Racquet 3d model | Sumo 3d model |
|---|---|---|
 |
 |
 |
| Scene 3d model | Burger 3d model | Loader |
|---|---|---|
 |
 |
 |
During development, one of the main challenges was using three.js modules in a WebView context. Since WebViews in Android do not support ES6 module syntax (e.g., `import { OrbitControls } from 'three/examples/jsm/...'), we had to find an alternative approach.
- All necessary three.js scripts (including
three.min.js,OrbitControls.js,GLTFLoader.js, etc.) were manually downloaded and bundled inside the/assetsfolder of the Android app. - Instead of using
importstatements, we switched to global script loading via<script>tags, maintaining compatibility with the WebView runtime. - 3D model loading, scene creation, and interaction logic were written inside a local
index.htmlfile, using global references to three.js components.
- Full offline support, no CDN or internet required.
- Avoids CORS or MIME-type issues when loading modules locally.
- Works seamlessly across all Android versions supporting WebView.
- Can’t use modern ES Modules (
import) or NPM-based three.js structure (Android JS file locker, so i use the oldi 0.125.0 build). - Debugging JavaScript inside WebView can be limited compared to browser tools.
- Need to keep scripts updated manually if three.js releases new features or fixes.
This approach ensures maximum compatibility while preserving the power of three.js in a constrained Android WebView environment.
✅ Embedded 3D models directly in a Jetpack Compose UI.
✅ Works entirely offline with locally bundled JS.
✅ Advanced interaction via touch and sensors.
✅ Modular, reusable Composable screens for 3D rendering.
✅ Complete separation between native and Web logic through a communication bridge.
