Anyone tried using glMultiDrawArraysIndirect? Compiler can't find the function - c++

Question

Has anyone successfully used glMultiDrawArraysIndirect? I'm including the latest glext.h but compiler can't seem to find the function. Do I need to define something (#define ... ) before including glext.h?
error: ‘GL_DRAW_INDIRECT_BUFFER’ was not declared in this scope
error: ‘glMultiDrawArraysIndirect’ was not declared in this scope
I'm trying to implement OpenGL superBible example. Here are snippets from source code :
GLuint indirect_draw_buffer;
glGenBuffers(1, &indirect_draw_buffer);
glBindBuffer(GL_DRAW_INDIRECT_BUFFER, indirect_draw_buffer);
glBufferData(GL_DRAW_INDIRECT_BUFFER,
NUM_DRAWS * sizeof(DrawArraysIndirectCommand),
draws,
GL_STATIC_DRAW);
....
// fill the buffers
.....
glMultiDrawArraysIndirect (GL_TRIANGLES, NULL, 3, 0);
I'm on Linux with Quadro 2000 & latest drivers installed (NVidia 319.60).

Answer 1

You cannot simply #include <glext.h> and expect this problem to fix itself. This header is only half of the equation, it defines the basic constants, function signatures, typedefs, etc. used by OpenGL extensions but does not actually solve the problem of extending OpenGL.
On most platforms you are guaranteed a certain version of OpenGL (1.1 on Windows) and to use any part of OpenGL that is newer than this version you must extend the API at runtime. Linux is no different, in order to use glMultiDrawArraysIndirect (...) you have to load this extension from the driver at runtime. This usually means setting up function pointers that are NULL until runtime in order to keep the compiler/linker happy.
By far, the simplest solution is going to be to use something like GLEW, which will load all of the extensions your driver supports for versions up to OpenGL 4.4 at runtime. It will take the place of glext.h, all you have to do is initialize the library after you setup your render context.