From 91bd63a196cefe98efc12e4979ad557aa78ff98a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sybren=20A=2E=20St=C3=BCvel?= <sybren@blender.org>
Date: Thu, 28 Apr 2022 17:16:04 +0200
Subject: CMake: Reduce dependencies of USD

`PXR_ENABLE_OSL_SUPPORT=OFF`: OpenShadingLanguage is an optional
dependency of the Imaging module. However, since that module was
included for its support for converting primitive shapes (sphere, cube,
etc.) to geometry, OSL is not necessary. Disabling it will make it
simpler to build Blender; currently only Cycles uses OSL.

`PXR_ENABLE_GL_SUPPORT=OFF`: GL support on Linux also links to X11
libraries. Enabling it would break headless or Wayland-only builds.
OpenGL support would be useful if someone wants to work on a Hydra
viewport in Blender; when that's actually being worked on, we could
patch in a new PXR_ENABLE_X11_SUPPORT option (to separate OpenGL from
X11) and contribute it upstream.

`PXR_BUILD_OPENIMAGEIO_PLUGIN=OFF`: It's used for loading image textures
in Hydra Storm / Embree renderers which we don't use.

Reviewed By: LazyDodo, brecht, makowalski

Differential Revision: https://developer.blender.org/D14792
---
 CMakeLists.txt                                |  3 +++
 build_files/build_environment/cmake/usd.cmake | 19 ++++++++++++++-----
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3a80fefac8c..06e9fba4aa9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -806,6 +806,9 @@ set_and_warn_dependency(WITH_IMAGE_OPENEXR WITH_OPENCOLORIO  OFF)
 # Haru needs `TIFFFaxBlackCodes` & `TIFFFaxWhiteCodes` symbols from TIFF.
 set_and_warn_dependency(WITH_IMAGE_TIFF WITH_HARU       OFF)
 
+# USD needs OpenSubDiv, since that is used by the Cycles Hydra render delegate.
+set_and_warn_dependency(WITH_OPENSUBDIV WITH_USD        OFF)
+
 # auto enable openimageio for cycles
 if(WITH_CYCLES)
   set(WITH_OPENIMAGEIO ON)
diff --git a/build_files/build_environment/cmake/usd.cmake b/build_files/build_environment/cmake/usd.cmake
index 3b5f9d21d95..8bf825a1c5f 100644
--- a/build_files/build_environment/cmake/usd.cmake
+++ b/build_files/build_environment/cmake/usd.cmake
@@ -25,7 +25,6 @@ set(USD_EXTRA_ARGS
   -DOpenImageIO_ROOT=${LIBDIR}/openimageio
   -DOPENEXR_LIBRARIES=${LIBDIR}/imath/lib/imath${OPENEXR_VERSION_POSTFIX}${LIBEXT}
   -DOPENEXR_INCLUDE_DIR=${LIBDIR}/imath/include
-  -DOSL_ROOT=${LIBDIR}/osl
   -DPXR_ENABLE_PYTHON_SUPPORT=OFF
   -DPXR_BUILD_IMAGING=ON
   -DPXR_BUILD_TESTS=OFF
@@ -36,8 +35,20 @@ set(USD_EXTRA_ARGS
   -DPXR_ENABLE_OPENVDB_SUPPORT=OFF
   -DPYTHON_EXECUTABLE=${PYTHON_BINARY}
   -DPXR_BUILD_MONOLITHIC=ON
-  -DPXR_ENABLE_OSL_SUPPORT=ON
-  -DPXR_BUILD_OPENIMAGEIO_PLUGIN=ON
+  # OSL is an optional dependency of the Imaging module. However, since that
+  # module was included for its support for converting primitive shapes (sphere,
+  # cube, etc.) to geometry, it's not necessary. Disabling it will make it
+  # simpler to build Blender; currently only Cycles uses OSL.
+  -DPXR_ENABLE_OSL_SUPPORT=OFF
+  # GL support on Linux also links to X11 libraries. Enabling it would break
+  # headless or Wayland-only builds. OpenGL support would be useful if someone
+  # wants to work on a Hydra viewport in Blender; when that's actually being
+  # worked on, we could patch in a new PXR_ENABLE_X11_SUPPORT option (to
+  # separate OpenGL from X11) and contribute it upstream.
+  -DPXR_ENABLE_GL_SUPPORT=OFF
+  # OIIO is used for loading image textures in Hydra Storm / Embree renderers,
+  # which we don't use.
+  -DPXR_BUILD_OPENIMAGEIO_PLUGIN=OFF
   # USD 22.03 does not support OCIO 2.x
   # Tracking ticket https://github.com/PixarAnimationStudios/USD/issues/1386
   -DPXR_BUILD_OPENCOLORIO_PLUGIN=OFF
@@ -70,9 +81,7 @@ add_dependencies(
   external_usd
   external_tbb
   external_boost
-  external_openimageio
   external_opensubdiv
-  external_osl
 )
 
 # Since USD 21.11 the libraries are prefixed with "usd_", i.e. "libusd_m.a" became "libusd_usd_m.a".
-- 
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