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Introduction
OpenGL is an interface to use the graphics card for graphics.
It only contains basic primitives, and is often used together with other higher level libraries such as GLUT.
OpenGL is only the interface, but there can be several implementations, open and closed source.
OpenGL is a C API with bindings to every language. So will will use C for the examples to minimize things.
Mesa
https://en.wikipedia.org/wiki/Mesa_%28computer_graphics%29
Dominant Linux desktop OpenGL implementation.
Contains a software implementation, but can also forward to hardware acceleration.
Open source.
Not certified by Khronos.
Used by the X server.
Requirement of freeglut.
OpenGL functions are prefixed with gl. Those are the lowest level functions of the API.
Libraries built on top of OpenGL
GLUT.
GLU
https://en.wikipedia.org/wiki/OpenGL_Utility_Library
Functions prefixed with glu
Mesa implements it apparently, e.g. dpkg shows libglu1-mesa.
GLEW
https://en.wikipedia.org/wiki/OpenGL_Extension_Wrangler_Library
GLFW
GLUT alternative. More features, more modern, thus recommended by some people.
http://stackoverflow.com/questions/25708688/what-is-the-difference-between-freeglut-vs-glfw
https://en.wikipedia.org/wiki/GLFW
One advantage over GLUT seems to be that it allows for more control over the event loop: http://gamedev.stackexchange.com/questions/8623/a-good-way-to-build-a-game-loop-in-opengl?lq=1
GLM
C++ Mathematics useful for OpenGL.
C alternatives?
glxinfo
Good way to get information on OpenGL in Linux:
glxinfo | grep -i opengl
Made for the X Window System, but also shows OpenGL information.
Users
- https://en.wikipedia.org/wiki/OGRE OpenGL rendering front-end that supports multiple backends, including Direct3D as well. Not a full game engine.