In Chapter 2, “Hello, Triangle: An OpenGL ES 2.0 Example,” we drew a triangle into a window using OpenGL ES 2.0, but we used some custom functions of our own design to open and manage the window. Although that simplifies our examples, it obscures how you might need to work with OpenGL ES 2.0 on your own systems.
As part of the family of APIs provided by the Khronos Group for developing content, a (mostly) platform-independent API, EGL, is available for managing drawing surfaces (windows are just one type; we’ll talk about others later). EGL provides the mechanisms for the following:
Communicating with the native windowing system of your system.
Querying the available types and configurations of drawing surfaces. ...