F3D is a fast, minimalist 3D viewer and rendering library (libf3d) built on VTK, providing both a desktop application and a reusable C++ library with bindings for C, Python, Java, and WebAssembly. It loads and interactively visualizes dozens of 3D file formats (glTF, USD, STEP, STL, OBJ, FBX, etc.) through a plugin architecture. The application offers a rich CLI, interactive console, configurable rendering options, animations, and scientific visualization features like volume rendering, scalar coloring, and point clouds. The library exposes a clean public API (engine, scene, window, camera, interactor, options) that can be embedded in other applications or used for offscreen rendering. The codebase demonstrates strong engineering: modular plugin system, extensive test suite (including pixel comparison and event recording), cross-platform support, and thorough documentation. Its architecture separates concerns cleanly between application layer, library, VTK extensions, and plugins, making individual components potentially reusable in other VTK-based projects.
OpenMoonRay is a physically-based, path-tracing renderer for animation and VFX, open-sourced by DreamWorks Animation and used in production for feature film rendering. The system supports both CPU and hybrid GPU (XPU) rendering, with physically based materials and lighting. It includes a custom scene description language (RDLA) and integrates with Pixar's USD (Universal Scene Description) via a Hydra render delegate plugin, enabling rendering of USD scenes through Houdini. The renderer is accompanied by a distributed computation framework called Arras, which allows interactive distributed rendering across local, multi-machine, or cloud environments. Key entry points include the `moonray` CLI for native RDLA scenes, `hd_render` for USD scenes, `moonray_gui` for Qt5-based scene viewing, and `arras_render` for distributed render viewing. The build system uses CMake with presets for Rocky Linux 9 and macOS, and supports Rez package management. External dependencies include USD, Houdini, Qt5, OpenEXR, OpenImageIO, OpenVDB, and numerous other libraries, many of which require custom patches. The repository also includes a regression testing suite (RATS) that compares canonical images against development renders, and a render profile viewer for performance analysis. While primarily a production application, the codebase incorporates research-oriented features such as quasi-Monte Carlo sampling, denoising via OpenImageDenoise, and physically accurate material models, giving it a hybrid character.