This option limits visibility of the glew.h header to just bf_gpu and intern_gawain

this is to highlight areas in the code that still directly do opengl calls or use
opengl types.

This is in preparation for supporting alternative rendering back-ends.

Reviewers: brecht, fclem

Differential Revision: https://developer.blender.org/D3304

CMakeLists.txt

@@ -458,11 +458,13 @@ endif()
 
 # OpenGL
 
+option(WITH_OPENGL              "When off limits visibility of the opengl headers to just bf_gpu and gawain (temporary option for development purposes)" ON)
 option(WITH_GLEW_ES             "Switches to experimental copy of GLEW that has support for OpenGL ES. (temporary option for development purposes)" OFF)
 option(WITH_GL_EGL              "Use the EGL OpenGL system library instead of the platform specific OpenGL system library (CGL, glX, or WGL)"       OFF)
 option(WITH_GL_PROFILE_ES20     "Support using OpenGL ES 2.0. (thru either EGL or the AGL/WGL/XGL 'es20' profile)"                                  OFF)
 
 mark_as_advanced(
+	WITH_OPENGL
 	WITH_GLEW_ES
 	WITH_GL_EGL
 	WITH_GL_PROFILE_ES20
@@ -1003,6 +1005,10 @@ endif()
 find_package(OpenGL)
 blender_include_dirs_sys("${OPENGL_INCLUDE_DIR}")
 
+if(WITH_OPENGL)
+	add_definitions(-DWITH_OPENGL)
+endif()
+
 if(WITH_SYSTEM_GLES)
 	find_package_wrapper(OpenGLES)
 endif()