filament

Filament is Google's real-time physically based rendering engine, the part of a 3D app that turns models, materials, and lights into the picture on screen. It runs on Android, iOS, Windows, Linux, macOS, and the web through WebGL2 and WebGPU, with backends for OpenGL, Metal, and Vulkan. Apache-licensed and completely free. Google uses it in its own products, which is about the strongest endorsement a graphics engine can get.

This is a rendering engine, not a game engine. No physics, no audio, no scripting, no full editor. You work in C++, with Java bindings for Android and a JavaScript path for the web, plus a material compiler you run at build time. Prebuilt releases ship through Maven Central and CocoaPods, so you don't have to compile it yourself unless you want to. It's built to be small and fast, with a clear bias toward mobile where every millisecond and megabyte counts.

If you're building a 3D viewer, an AR feature, or a custom app that needs PBR-quality visuals without dragging in Unity or Unreal, this is the lean option. Solo and small teams: a great fit if you can write C++ or use the web bindings. Larger teams shipping cross-platform graphics get one engine that covers every target.

The catch is that rendering-only means you build everything around it. Scene management, input, asset pipeline, gameplay logic: all on you. Filament draws beautifully and does nothing else. If you want batteries included, reach for Godot or a full engine instead.