I set the following values
OSMESA_INCLUDE_DIR /home/angainor/mesa/install/include
OSMESA_LIBRARY /home/angainor/mesa/install/lib/x86_64-linux-gnu/libOSMesa.so
When I run make VERBOSE=1, the include path is not seen on the command line when compiling ThirdParty/glew/. That’s why I tried to add it explicitly to compile flags. I looks like CMake is not using those variables, or at least not everywhere where it should.