What is an OpenGL Extension Library, Loading Library, Binding Library?

Question

What is an OpenGL Extension Library, Loading Library, Binding Library?

Why are they needed?

Can you explain in easy and plain layman's terms?

Answer 1

The first thing to understand is that OpenGL is just the specification of a set on methods to interacts with your GPU. Then if you are on windows or linux, your GPU vendor will provide a driver that comes with an implementation of this specification. If you are on OSX, the implemetation is shipped with your OS.

To use OpenGL, you need an OpenGL context. It is essentially some memory that will hold the current state of OpenGL internal state machine. To create such context, you should use a binding library like glfw or freeglut.

Then you need to access the OpenGL methods. On Windows, you have opengl32.dll​ library that gives access to legacy OpenGL1.1 only ! If you want to use modern OpenGL, you need to get the pointers to the functions exposed by the driver. There are several loading library for that. I think the most common one is glew.

OpenGL allows GPU vendors to provide custom extentions to the specification. You can retrieve these functions the same way you do for normal OpenGL functions. Once again, I would recommand to use glew which is also a extention library.

Then you need a header to have the prototypes for all these functions. But glew also handles that actually.