For those who don’t know the tool: MoonRay is DreamWorks Animation’s in-house Monte Carlo path tracer, open-sourced in 2023 under Apache 2.0. It drives DreamWorks’ film rendering pipeline and supports hybrid CPU/GPU (XPU) modes. MoonRay integrates with DCCs via its Hydra delegate (hdMoonRay) for tools such as Houdini and Katana. The project includes the Arras framework for distributed rendering and collaboration across clusters.
Light Path Visualiser Enters the Scene
The new light path visualiser in moonray_gui is the most visible change in version 2.34.0.1. It lets artists trace how rays travel through a scene, showing how light interacts with surfaces, volumes, and materials. The visualisation is colour-coded by ray type and can reveal sampling or shading inconsistencies that are otherwise invisible. It also serves as a diagnostic tool for debugging light source or material behaviour.
Platform Updates: macOS Tahoe Joins, Linux Builds Simplified
MoonRay can now build natively on macOS Tahoe, with Sonoma and Sequoia still supported. The renderer also benefits from dependency updates and inculde fixes, easing compilation on a broader range of Linux distributions. The release aligns with both VFX Reference Platform 2024 and 2025, ensuring compatibility with current production libraries and compilers.
New Features Across the Pipeline
Version 2.34.0.1 expands flexibility for lighting and shading setups. Per-lobe lightsets are now available in both vector and XPU modes, allowing finer control of multi-lobe BSDFs. Image maps gain bindable “scale” and “offset” attributes, and SceneVariables documentation for image sizing has been clarified. Performance-wise, MoonRay now shares CPU and memory affinity data between processes using shared memory, improving parallel job efficiency. Timing measurements have switched to a more efficient RDTSC-based method for NUMA [non-uniform memory access] systems, offering more stable profiling results. Artists can also now select lights and cameras for object-space transformations directly in map shaders, simplifying custom shading graph workflows.
Fixes: From Subsurface Scatter to Fisheye Crashes
A long list of bug fixes makes this release notably production-friendly. Key repairs include:
- Fixed a mesh tessellation issue in tiled renders with the FisheyeCamera.
- Resolved DwaTwoSidedMaterial artefacts caused by previous lobe lightset work.
- Corrected crashes when exceeding BSDF lobe limits or loading oversized MeshLights, which now trigger warnings instead.
- Addressed a memory usage spike in vector and XPU modes.
- Fixed missing lightset assignments in vector subsurface scattering and adjusted over-bright subsurface shading on creases.
- Corrected normal direction errors in scalar mode and improved TransformSpaceMap behaviour.
- Fixed adaptive light sampling, volume bounce contributions, and a crash in OpenImageIO 2.4.8 statistics when no images were opened.
Under the Hood: Clean-Up and Refactoring
DreamWorks also restructured several internal libraries. The noise library moved from moonshine/lib/common to moonray/lib/common, simplifying dependencies. The integrator logic for Cryptomatte was reduced in complexity, and redundant intersection path types were removed. Code clean-up continues across lib/rendering/shading, improving maintainability without changing behaviour.
Availability
MoonRay 2.34.0.1 is available now as open-source via the official repository. It can be compiled for Linux and macOS (Tahoe, Sonoma, and Sequoia). GPU rendering requires NVIDIA CUDA/OptiX or Apple Silicon.
Caution Before Production
As with any open-source renderer update, production users should validate the build and test scene compatibility before deployment in live pipelines.
