UniVRM, a Unity plugin for handling VRM (Virtual Reality Model) files, is not limited to static content development—it also excels in dynamic, real-time runtime applications. As interactive experiences become increasingly personalized and avatar-driven, the ability to load, display, and manage 3D humanoid models during runtime is essential for developers across gaming, simulation, and virtual communication platforms.
Designed with flexibility in mind, UniVRM leverages Unity’s asynchronous programming capabilities, allowing seamless runtime import and manipulation of VRM models. This makes it an ideal solution for applications requiring real-time avatar switching, user-generated content integration, and immersive, character-based interaction.
Key Runtime Features
Runtime Import
UniVRM allows developers to load VRM files during application runtime. This is essential for scenarios where users select or upload avatars dynamically. Using Unity’s file I/O or web-based data fetching, avatars can be imported directly into the game or application environment without restarting or reloading scenes.
Key benefits:
- Supports both local and remote VRM files
- Async/await compatibility ensures smooth user interaction
- Automatically generates humanoid rig, materials, and blend shapes
Runtime Export
In addition to importing avatars, UniVRM enables runtime export. Users can modify avatars—such as changing blend shapes, textures, or materials—and then export these changes to a new VRM file. This feature is particularly useful for applications that support avatar customization, character saving, or user-generated content.
Capabilities include:
- Exporting with updated metadata
- Preserving or modifying bone structure and mesh
- Optional compression for mobile deployment
Metadata Access
VRM files contain embedded metadata such as the avatar’s name, creator, license terms, version, and usage permissions. UniVRM exposes this metadata through its API, allowing developers to access and display it dynamically or restrict features based on license types.
Supported operations:
- Reading metadata on load
- Updating license or author information
- Enforcing content guidelines
Animation Integration
UniVRM supports VRM Animation files (.vrma), which can be loaded at runtime to animate avatars based on external or user-defined sequences. This includes facial expressions, gestures, and full-body movements.
Key animation features:
- VRM blend shape proxy support
- Runtime animation control via scripts
- Compatibility with Unity’s Animator and Timeline systems
Use Case Examples
VTuber Applications
VTubing platforms heavily rely on real-time avatar switching and expression control. UniVRM makes it possible to load a viewer’s or streamer’s custom avatar live, apply expressions, sync with motion capture, and perform in front of a virtual camera—all within Unity.
Features used:
- Runtime VRM import/export
- Blend shape and bone control
- Real-time metadata integration
Games and Virtual Worlds
Multiplayer games and metaverse environments require each user to have a unique presence. UniVRM supports dynamic avatar loading, enabling players to upload their own models. These avatars can be animated, interacted with, and customized mid-session.
Ideal for:
- Social games
- Sandbox platforms
- Character-centric MMORPGs
Educational & Simulation Software
In training simulations or educational VR experiences, avatars can represent learners or instructors. Using UniVRM, developers can load specific character models per user and modify them in real time to reflect roles, tasks, or learning stages.
Applications include:
- Virtual classrooms
- Corporate training modules
- Health and therapy simulations
Technical Requirements
Unity Version Compatibility
UniVRM is best used with Unity LTS versions for maximum stability and support. As of now, versions 2020.3 and 2022.3 are recommended.
Why LTS matters:
- Ensures long-term bug fixes
- Better compatibility with .NET features
- Reduces import/export conflicts
NET and Scripting Backend
UniVRM requires .NET 4.x support and is compatible with IL2CPP scripting backends. This ensures robust cross-platform builds, including WebGL and mobile deployments.
Best practices:
- Enable .NET 4.x in Player Settings
- Use IL2CPP for final builds
Core Components
To fully utilize UniVRM, the following packages must be included:
UniGLTF: For glTF parsing and handlingVRMShaders: Shader support for proper renderingUniVRM: The main runtime and editor package
Performance Considerations
Resource Management
Runtime importing of VRM models can be resource-intensive depending on the complexity of the avatar. It’s important to manage both CPU and GPU usage efficiently to avoid bottlenecks.
Recommendations:
- Optimize mesh complexity beforehand
- Use compressed textures
- Limit bone count where possible
Optimization Strategies
To ensure stable performance during runtime avatar handling:
- Preload Assets: Load commonly used avatars in advance.
- Level of Detail (LOD): Use LODs to reduce rendering load.
- Asynchronous Operations: Always use async methods for file loading.
Mobile and WebGL Optimization
For platforms with limited resources:
- Reduce texture resolutions to 1024×1024 or lower
- Use mobile-optimized shaders
- Manage garbage collection frequency to prevent spikes
Limitations and Best Practices
Platform-Specific Limitations
WebGL and mobile platforms impose certain memory and execution constraints. UniVRM works well within these limits if assets are optimized.
Common limitations:
- Memory caps on WebGL (~512MB typical)
- Limited support for complex shaders
- File access limitations (e.g., no local file uploads on some mobile browsers)
Recommended Avatar Guidelines
To maintain performance and compatibility:
- Keep avatar file sizes under 15MB
- Use 2–3 material slots max
- Limit blend shapes to essential expressions
Error Handling
Robust error management ensures smooth runtime performance:
- Check file integrity before import
- Use try/catch for async loading
- Implement fallback avatars for corrupted files
Conclusion
UniVRM is a powerful, production-ready solution for real-time avatar handling in Unity applications. Its thoughtful design enables seamless import, export, and control of 3D humanoid models during application execution, opening new possibilities for personalized, immersive user experiences.
Whether you’re building a social game, a VTuber streaming tool, or an educational simulator, UniVRM offers the flexibility and performance needed to integrate lifelike, customizable avatars into your runtime environments. With support for modern Unity practices, cross-platform builds, and performance optimization, UniVRM is the preferred choice for developers serious about real-time 3D interaction.