OpenGL for Embedded Systems (OpenGL ES) is a subset of the OpenGL 3D graphics application programming interface (API) designed for embedded systems such as mobile phones, PDAs, and video game consoles. OpenGL ES is managed by the not-for-profit technology consortium, the Khronos Group, Inc.
Versions
Several versions of the OpenGL ES specification now exist. OpenGL ES 1.0 is drawn up against the OpenGL 1.3 specification, OpenGL ES 1.1 is defined relative to the OpenGL 1.5 specification and OpenGL ES 2.0 is defined relative to the OpenGL 2.0 specification. This means that, for example, an application written for OpenGL ES 1.0 should be easily portable to the desktop OpenGL 1.3; as the OpenGL ES is a stripped-down version of the API the reverse may or may not be true, depending on the particular features used.
Version 1.0 and 1.1 both have common and common lite profiles, the difference being that the common lite profile only supports fixed-point instead of floating point data type support, whereas common supports both.
OpenGL ES 1.0
Contained much functionality stripped from the original OpenGL API and a little bit added. Two of the more significant differences between OpenGL ES and OpenGL are the removal of the glBegin ... glEnd calling semantics for primitive rendering (in favor of vertex arrays) and the introduction offixed-point data types for vertex coordinates and attributes to better support the computational abilities of embedded processors, which often lack a floating point unit (FPU). Many other functions were removed in version 1.0 to produce a lightweight interface: for example, quad and polygon primitive rendering, texgen, line and polygon stipple, polygon mode, antialiased polygon rendering (with alpha border fragments, not multisample), ARB_Image class pixel operation functionality, bitmaps, 3D texture, drawing to the frontbuffer, accumulation buffer, copy pixels, evaluators, selection, feedback, display lists, push and pop state attributes, back-face material parameters, and user defined clip planes.
OpenGL ES 1.1
Adds to the OpenGL ES 1.0 functionality by introducing additional features such as mandatory support for multitexture, better multitexture support (with combiners and dot product texture operations), automatic mipmap generation, vertex buffer objects, state queries, user clip planes, and greater control over point rendering.
OpenGL ES 2.0
OpenGL ES 2.0 was publicly released in March 2007. It eliminates most of the fixed-function rendering pipeline in favor of a programmable one. Almost all rendering features of the transform and lighting pipelines, such as the specification of materials and light parameters formerly specified by the fixed-function API, are replaced by shaders written by the graphics programmer. As a result, OpenGL ES 2.0 is not backward compatible with OpenGL ES 1.1. 2.0 also goes agnostic on the handedness of the coordinate system, and many implementations seem to be left handed, in contrast to OpenGL history.
