MrRay

Meet MrRay (pronounced "Mister Ray") – a passion-driven path-tracing renderer that began as a hobby and now has taken on a life of its own. It's the result of my fascination with physically based rendering and has turned into a creative sandbox where I tinker with various algorithms and ideas. What started as an adventure inspired by the "Ray Tracing in One Weekend" book series has now blossomed into something entirely unique.

USD Hydra support

Rather than developing a custom scene description format exclusive to the engine, I've chosen to create a "USD Hydra render delegate" instead. This strategic decision empowers MrRay to function as a renderer for any software capable of channeling scene description to Hydra. This approach not only removes the need for crafting individual translators for each software I intend to integrate MrRay with but also streamlines its compatibility across multiple platforms.

I've developed a dedicated plugin for Blender, seamlessly integrating MrRay as a render delegate. You can find the plugin in a separate repository called MrRayBlenderAddon. Notably, the rendered image you see above, showcasing Pixar's kitchen set, was generated within Blender using MrRay at a sampling rate of 150 samples per pixel. The entire rendering process concluded in approximately 13 minutes.

For more information on Hydra, Pixar has a good presentation here

Cornell box demo

To test out MrRay, I have developed a quick demo application which renders a slightly modified "Cornell box" scene.

The following command:

mrRayDemo --width 3996 --height 2000 --spp 600 output.jpg

Produces this raw image:

Requirements

• Core dependencies:
  • OpenImageIO (tested against v2.4.12.0)
• Cornell box demo dependencies:
  • argparse (tested against v2.9)
• Hydra render delegate dependencies:
  • OpenUSD (tested against v23.05)

Building

MrRay uses CMake for its build system. The following options are available:

• MR_RAY_BUILD_HYDRA - controls whether to build the MrRay Hydra render delegate (off by default)
• MR_RAY_BUILD_DEMO - controls whether to build the Cornell box demo (off by default)
• ARGPARSE_INCLUDE_DIR - path to the argparse include directory

Example build/install

Run the commands below inside your build directory to install MrRay. A successful build is not guaranteed with these commands alone, you may need to point CMake to USD/OIIO libraries.

cmake \
    -DMR_RAY_BUILD_HYDRA=On \
    -DMR_RAY_BUILD_DEMO=On \
    -DARGPARSE_INCLUDE_DIR=[argparse include directory] \
    -DCMAKE_INSTALL_PREFIX=[installation path] \
    -DCMAKE_BUILD_TYPE=Release \
    [path to MrRay]
cmake --build .
cmake --install .