CMP0072

FindOpenGL prefers GLVND by default when available.

The FindOpenGL module provides an OpenGL::GL target and an OPENGL_LIBRARIES variable for projects to use for legacy GL interfaces. When both a legacy GL library (e.g. libGL.so) and GLVND libraries for OpenGL and GLX (e.g. libOpenGL.so and libGLX.so) are available, the module must choose between them. It documents an OpenGL_GL_PREFERENCE variable that can be used to specify an explicit preference. When no such preference is set, the module must choose a default preference.

CMake 3.11 and above prefer to choose GLVND libraries. This policy provides compatibility with projects that expect the legacy GL library to be used.

The OLD behavior for this policy is to set OpenGL_GL_PREFERENCE to LEGACY. The NEW behavior for this policy is to set OpenGL_GL_PREFERENCE to GLVND.

This policy was introduced in CMake version 3.11. CMake version 3.19.0-rc3 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.