MoonRay Source Structure

openmoonray is the top-level repository for MoonRay open source. The actual source code is contained in a number of other repositories referenced as git submodules.


At the top-level, arras contains repositories relating to the Arras execution and process communication system. Most of the code under arras is independent of MoonRay, and can be built and used separately if desired.

  • arras/arras4_core links to a repository containing the C++ libraries implementing Arras. The libraries are required by the example application arras_render, and by the MoonRay Hydra plugin HdMoonray.

  • arras/arras_render is a Qt5 application that provides an example of MoonRay integration using Arras. It needs the MoonRay libraries to build and run.

  • arras/distributed contains additional code needed to use Arras in distributed mode. arras4_node is a C++ service that runs on every render machine, minicoord is a Python service that manages a pool of render machines.


The top-level moonray directory contains the repositories that implement MoonRay and its associated plugins. Most of the code under moonray doesn’t require Arras to build, but it is needed by the moonray_arras libraries and by the Hydra plugin HdMoonRay.

  • moonray/scene_rdl2 is the repository that provides MoonRay’s scene representation and a number of utility libraries.

  • moonray/moonray is the repository that implements the MoonRay render engine and the moonray command-line renderer. The code is divided into roughly 20 libraries. moonray also contains a set of basic scene object (shader) plugins.

  • moonray/moonray_dcc_plugins plugins for using moonray nodes in third-party DCC tools

  • moonray/moonray_gui implements the moonray_gui Qt application, that can be used to view render progress and final results.

  • moonray/render_profile_viewer a Python tool for comparing render logs

  • moonray/moonshine contains a far more extensive set of scene object plugins.

  • moonray/moonshine_usd has the Usd and UsdInstance scene objects.

  • moonray/moonray_arras contains the client and server components needed to use MoonRay with Arras.

  • moonray/hydra has the Hydra plugin for MoonRay, HdMoonRay.

  • moonray/mcrt_denoise has the denoiser code.