v1.15.0.0-beta1

Release 1.15 (Jan 1?, 2026) -- compared to 1.14

• Beta 1: Dec 20, 2025

New minimum dependencies, toolchain, and compatibility changes:

• Python: 3.9 minimum (from 3.7) #2017 (1.15.0.0)
• LLVM: Raise llvm minimum to 14.0 (from 11.0). #2019 (1.15.0.0)

✏️ OSL Language, standard library, and oslc compiler (for shader writers):

• No changes to the language in this release.

⛰️ API changes and new ShadingSystem features (for renderer writers):

• BSDL Library: The internal Imageworks BSDF library has been open sourced and included with OSL as a header-only library for renderer authors. #1986 (by Alejandro Conty) (1.15.0.0) And subsequent enhancements:
  • bsdl: Implement MX conductor with multiple scattering #1991 (by Alejandro Conty) (1.15.0.0)
  • bsdl: Change MX conductor to sample bounded visible normals #2000 (by Alejandro Conty) (1.15.0.0)
  • bsdl: Add BSDF for MaterialX dielectric with Multiple Scattering #2009 (by Alejandro Conty) (1.15.0.0)
• Continued work on "rs free function" migration:
  • api: Add rs_allocate_closure free function. #1944 (by Curtis Black) (1.15.0.0)

☀️ testshade/testrender/osltoy improvements

• testrender: Fix uv derivatives for testrender [#1978] #2037 (by Alexey Smolenchuk) (1.14.8.0, 1.15.0.0)
• testrender: Default to identity for unknown testrender xforms #2043 (by Chris Hellmuth) (1.14.8.0, 1.15.0.0)

🐛/🔧 Internals: fixes, improvements, and developer concerns

• perf: Share Shading Context when optimizing/jitting a shader #1952 (by Alex Wells) (1.15.0.0)
• fix: Check for errors in ShadingSystem::ReParameter() #1998 (by cmstein) (1.15.0.0)
• fix: Pass the real number of channels to rs_texture and rs_texture3d on gpu #2004 (1.15.0.0)
• int: LLVM_Util::supports_isa is not thread-safe #2029 (by Sergey Sharybin) (1.15.0.0)

🏗 Build/test/CI and platform ports

• CMake build system and scripts:
  • build: Link batched libraries with liboslexec #1987 (by John Haddon) (1.15.0.0)
  • build: Simplify FindOptiX.cmake a bit now that OptiX 7 is the minimum #1988 (1.15.0.0)
  • build: Update include directives for OpenImageIO_ROOT #1997 (by cmstein) (1.15.0.0)
  • build: Serialize builds in testshade #2012 (by Jean-Francois Panisset) (1.15.0.0)
  • build: Simplify some clauses involving old compilers #2016 (1.15.0.0)
  • build/batch: Batch shading compiler directives were wrong #2015 (1.15.0.0)
  • build/windows: Ensure 'lib' prefix is on the dynamicaly loaded batched shading libraries for windows #2025 (by Alex Fuller) (1.15.0.0)
  • build: Use generator expressions to find oslc and compile shaders with it #2026 (by Alex Fuller) (1.15.0.0)
  • build: Suppress warning for SIMD loop vectorization failure with clang #2032 (1.15.0.0)
  • build: Fix compiler warnings with clang 21 + C++20 #2033 (1.15.0.0)
• Dependency version support:
  • deps: Remove unused symbol that was removed from OIIO main #1984 (1.15.0.0)
  • deps: Add compatibility with LLVM 20.1 #1993 (by Sven-Hendrik Haase) (1.15.0.0)
  • deps: Test against pybind11 3.0 and minor fixes #2007 (1.15.0.0)
  • deps: Test C++20 and gcc14 + fixes needed #2010 (1.15.0.0)
  • deps: Use more modern span-based set_pixels with OIIO 3.1. #2042 (1.15.0.0)
  • deps: Add compatibility with LLVM 21 #2030 (by Christian Heusel) #2034 (by Alex Fuller) (1.15.0.0)
• Testing and Continuous integration (CI) systems:
  • ci: Get OptiX headers from new improved location #1989 (1.15.0.0)
  • ci: Remove Windows-2019 job #1990 (1.15.0.0)
  • ci: GPU/OptiX full build and test #1992 (1.15.0.0)
  • ci: Improve CI caching scheme #1994 (1.15.0.0)
  • ci: Add vp2025 test #1995 (1.15.0.0)
  • ci: Fix Windows CI with special LLVM pre-build #2011 (1.15.0.0)
  • tests: Add optix ref output for new test added in PR 1991 #1996 (1.15.0.0)
  • ci: Add a VFX 2026 platform test #2020 (1.15.0.0)
  • ci: Adjust comparison threshold for render-microfacet test #2027 (1.15.0.0)
  • ci: Adjust test matrix for recent OIIO and OCIO releases #2028 (1.15.0.0)
  • ci: Drop deprecated macos-13 (intel) platform, add macos-15-intel #2031 (1.15.0.0)
  • ci: Unbreak optix jobs by locking down container #2041 (1.15.0.0)
  • ci: Bump 'latest' test dependency versions #2038 (1.15.0.0)
  • ci: Use bigger runner for icx job variation, needs more disk space #2047 (1.15.0.0)
  • ci: Fix failing render-microfacet.opt test #2048 (1.15.0.0)
  • ci: Fix change deprecated sonarqube action, improve run conditions #2052 (1.15.0.0)
• Platform support:
  • build(Mac): Fix various MacOS problems with GitHub and CMake #1982 (1.15.0.0)

🏢 Project Administration

• admin: Set up new issue templates #1981 (1.15.0.0)