by Fabian Giesen - Comprehensive and rich series about the D3D/OpenGL graphics pipeline
Open-Awesome is built by the community, for the community. Submit a project, suggest an awesome list, or help improve the catalog on GitHub.
The LWJGL 3 Wiki
by Joe Groff - Brief introduction to the building blocks of OpenGL
by Rich Geldreich - Constructive (or not) criticism of GL API