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. OpenGL ES is managed by the not-for-profit technology consortium, the Khronos Group, Inc.
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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. 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.
In creating OpenGL ES 1.0, much functionality has been 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 of fixed-point data types for vertex coordinates and attributes to better support the computational abilities of embedded processors, which often lack an FPU. Many other areas of functionality have been 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, two-sided lighting, 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, publicly released in March 2007[1], 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 backwards compatible with OpenGL ES 1.1.
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.
Usage
OpenGL ES 1.0 has been chosen as the official 3D graphics API in Symbian OS[2] and the Android platform[3].
OpenGL ES 1.0 plus some features of 2.0 and Cg are supported by the Playstation 3 as one of official graphics APIs [4] (the other one being low level libgcm library).
OpenGL ES 1.1[5] is one of the 3D libraries for the iPhone SDK.[6]
OpenGL ES 1.0 and 1.1 are supported in the BlackBerry 5.0 operating system series[7]. However, only the BlackBerry Storm 2 and the BlackBerry Curve 8530 have the hardware to support OpenGL ES 1.x[8]. Future models will support OpenGL ES as well.
OpenGL ES 2.0 will be used as the 3D library for the Pandora console and is one of the 3D libraries for the iPhone SDK (only enabled for the iPhone 3GS and the new iPod Touch, due to hardware changes required to support OpenGL ES 2.0). It is also rumored that Windows Mobile 7 [9] from Microsoft will also support OpenGL ES 2.0. This version was also chosen[10] for WebGL, OpenGL for browsers.
Further reading
- Kari Pulli, Tomi Aarnio, Ville Miettinen, Kimmo Roimela, and Jani Vaarala: Mobile 3D Graphics with OpenGL ES and M3G, Morgan Kaufmann, 2007, ISBN 0-12373-727-3
- Dave Astle and David Durnil: OpenGL ES Game Development, Course Technology PTR, ISBN 1-59200-370-2
- Kari Pulli, Tomi Aarnio, Kimmo Roimela, and Jani Vaarala Designing graphics programming interfaces for mobile devices, IEEE CG&A 2005
- Aaftab Munshi, Dan Ginsburg, Dave Shreiner : OpenGL(R) ES 2.0 Programming Guide, Addison-Wesley Professional, ISBN 978-0321502797
References
- ^ http://www.khronos.org/news/press/releases/finalized_opengl_es_20_specification/
- ^ Symbian OS v9.5 product sheet, Symbian
- ^ What is Android?, Google
- ^ OpenGL ES demo in PPT format
- ^ OpenGL and Mobile Devices
- ^ iPhone Dev Center
- ^ "New in this beta release". Release Notes - BlackBerry Java Application. Research in Motion. http://docs.blackberry.com/en/developers/deliverables/11953/New_in_this_beta_release_895185_11.jsp. Retrieved 2009-12-08.
- ^ Koh, Damian (2009-11-29). "What to expect for BlackBerry smartphones". CNET Asia. http://asia.cnet.com/reviews/mobilephones/0,39050603,62059292,00.htm. Retrieved 2009-12-08.
- ^ Could this be the hardware spec for Microsofts Pink Phone?
- ^ Khronos Details WebGL Initiative to Bring Hardware-Accelerated 3D Graphics to the Internet
External links
- Official website
- Public bug tracking
- OpenGL ES Conformant companies
- Public forums
- List of OpenGL ES compatible devices
- The Firefox effort to support 3D based on OpenGL ES with the <canvas> tag
- gDEBugger ES - OpenGL ES Debugger and Profiler including an OpenGL ES implementation on a Windows PC operating system
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