[GNU/Linux] [Debian 12] CMake fails to find OpenGL when MESA has been built without GLX support

vanfanel · May 24, 2024, 2:36pm

Hello there!

CMake (version included in Debian 12 and also latest stable cmake version 3.29.3) fails to find OpenGL when doing find_package(OpenGL REQUIRED) if MESA is built without GLX support:
This is the error I get:

CMake Error at /usr/local/lib/python3.11/dist-packages/cmake/data/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find OpenGL (missing: OPENGL_glx_LIBRARY)
Call Stack (most recent call first):
/usr/local/lib/python3.11/dist-packages/cmake/data/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
/usr/local/lib/python3.11/dist-packages/cmake/data/share/cmake-3.29/Modules/FindOpenGL.cmake:579 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
cmake/ncine_imported_targets.cmake:210 (find_package)
CMakeLists.txt:73 (include)

According to this doc, CMake should find the GLVND OpenGL implementation without any problems using find_package(OpenGL REQUIRED) → https://cmake.org/cmake/help/latest/policy/CMP0072.html

This is how my MESA build is configured:

meson setup -Dbuildtype=release -Dglx=disabled -Dplatforms=wayland \
-Dvulkan-drivers=intel -Dgallium-drivers=iris,kmsro,zink -Dglvnd=enabled ..

GLVND is in fact found by CMake if I do:

FIND_LIBRARY(OpenGL_LIBRARY OpenGL)
SET(EXTRA_LIBS ${OpenGL_LIBRARY})

…and CMake also links properly against GLVND OpenGL implementation if I do this:

target_link_libraries(${NCINE_APP} PUBLIC ${OpenGL_LIBRARY})

Any idea on WHY find_package(OpenGL REQUIRED) fails???

Many, many projects I use tend to do that, and I have to manually modify their CMake files and hack-in a solution, but I am almost sure this is on CMake.

vanfanel · May 24, 2024, 2:49pm

Also, it seems that doing this works:

set(OPENGL_USE_OPENGL ON)
find_package(OpenGL REQUIRED)

It seems to be because of this:

github.com

Kitware/CMake/blob/47ba19f346d03123c59ee5a3fe36d32a43b96359/Modules/FindOpenGL.cmake#L455


      
             (NOT OPENGL_USE_EGL AND
                  OPENGL_opengl_LIBRARY AND
                  OPENGL_glx_LIBRARY) OR
             (NOT OPENGL_USE_GLES3 AND
              NOT OPENGL_USE_GLES2 AND
                  OPENGL_USE_EGL))
            list(APPEND _OpenGL_REQUIRED_VARS OPENGL_opengl_LIBRARY)
          endif()
          
          # GLVND GLX library.  Preferred when available.
          if((NOT OPENGL_USE_OPENGL AND
              NOT OPENGL_USE_GLX AND
              NOT OPENGL_USE_EGL AND
              NOT OPENGL_USE_GLES3 AND
              NOT OPENGL_USE_GLES2 AND
              NOT OPENGL_glx_LIBRARY AND
              NOT OPENGL_gl_LIBRARY) OR
             (    OPENGL_USE_GLX AND
              NOT OPENGL_USE_EGL AND
              NOT OPENGL_USE_GLES3 AND
              NOT OPENGL_USE_GLES2 AND

…but that contradicts CMake docs in that set(OPENGL_USE_OPENGL ON) shouldn’t be needed when GLVND is installed because GLVND whould be preferred instead of legacy GLX.