OpenGL ES (OpenGL for Embedded Systems) is a subset of the OpenGL 3D graphics API designed for embedded devices such as mobile phones, PDAs, and video game consoles. It is defined and promoted by the Khronos Group, a graphics hardware and software industry consortium interested in open APIs for graphics and multimedia.
In creating OpenGL ES 1.0, much functionality has been stripped from the original OpenGL API and a little bit added.
The definition given by the Khronos group:
« OpenGL® ES is a royalty-free, cross-platform API for full-function 2D and 3D graphics on embedded systems – including consoles, phones, appliances and vehicles. It consists of well-defined subsets of desktop OpenGL, creating a flexible and powerful low-level interface between software and graphics acceleration. OpenGL ES includes profiles for floating-point and fixed-point systems and the EGL™ specification for portably binding to native windowing systems. OpenGL ES 1.X is for fixed function hardware and offers acceleration, image quality and performance. OpenGL ES 2.X enables full programmable 3D graphics. OpenGL SC is tuned for the safety critical market. » (http://www.khronos.org/opengles/)
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. 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 in lieu of floating point data type support, whereas common supports both.
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.
The common profile for OpenGL ES 2.0, publicly released in August 2005, completely eliminates all fixed-function API support in favor of an entirely programmable model, so features like the specification of surface normals in the API for use in a lighting calculation are eliminated in favor of abstract variables, the use of which is defined in a shader written by the graphics programmer.
OpenGL ES also defines an additional safety-critical profile that is intended to be a testable and demonstrably robust subset for safety-critical embedded applications such as glass cockpit avionics displays.
OpenGL ES has been chosen as the official graphics API in Symbian OS.
