The OpenGL ES Reference Pages
The reference pages for OpenGL ES 3.0 include complete descriptions of all OpenGL ES commands and functions contained in the OpenGL ES 3.0 API and Shading Language Specifications.
The OpenGL ES 2.0 reference pages include descriptions of all OpenGL ES commands contained in the OpenGL ES 2.0 Specification.
The OpenGL ES Registry, hosted outside of the SDK, contains the formal Specifications for OpenGL ES and the OpenGL ES Shading Language, as well as for companion APIs like EGL. Specifications are the authoritative documents about how OpenGL ES is intended to work. They are also the most difficult to read, being written primarily for OpenGL ES implementers, not developers using OpenGL ES; so you may find the reference pages combined with tutorials to be a better choice.
The Registry also contains specifications for extensions describing optional features of OpenGL ES, and header files defining interfaces for extensions. Extension specifications are written as supplements to the core OpenGL ES Specifications. Most new features are first introduced as extensions and only later become part of a core OpenGL ES version, so using extensions is important to staying current with the evolution of the API.
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