OpenGL ES

OpenGL for Embedded Systems (OpenGL ES or GLES) is a subset^[2] of the OpenGL computer graphics rendering application programming interface (API) for rendering 2D and 3D computer graphics such as those used by video games, typically hardware-accelerated using a graphics processing unit (GPU). It is designed for embedded systems like smartphones, tablet computers, video game consoles and PDAs. OpenGL ES is the "most widely deployed 3D graphics API in history".^[3]

The API is cross-language and multi-platform. The libraries GLUT and GLU are not available for OpenGL ES. OpenGL ES is managed by the non-profit technology consortium Khronos Group. Vulkan, a next-generation API from Khronos, is made for simpler high performance drivers for mobile and desktop devices.^[4]

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.

OpenGL ES comes with its own version of shading language (OpenGL ES SL), which is different from OpenGL SL.^[5]

Version 1.0 and 1.1 both have common (CM) and common lite (CL) 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

OpenGL ES 1.0 was released publicly July 28, 2003. OpenGL ES 1.0 is based on the original OpenGL API, with much functionality removed and a little bit added. One significant difference between OpenGL and OpenGL ES is that OpenGL ES removed the need to bracket OpenGL library calls with glBegin and glEnd. Other significant differences are that the calling semantics for primitive rendering functions were changed in favor of vertex arrays, and fixed-point data types were introduced for vertex coordinates. Attributes were also added to better support the computational abilities of embedded processors, which often lack a floating point unit (FPU). Many other functions and rendering primitives were removed in version 1.0 to produce a lightweight interface, including:

• quad and polygon rendering primitives,
• texgen, line and polygon stipple,
• polygon mode and antialiased polygon rendering are not supported, although rendering using multisample is still possible (rather than alpha border fragments),
• ARB_Image pixel class operation are not supported, nor are bitmaps or 3D textures,
• several of the more technical drawing modes are eliminated, including frontbuffer and accumulation buffer. Bitmap operations, specifically copying pixels (individually) is not allowed, nor are evaluators, nor (user) selection operations,
• display lists and feedback are removed, as are push and pop operations for state attributes,
• some material parameters were removed, including back-face parameters and user defined clip planes.

OpenGL ES 1.1

OpenGL ES 1.1 added features such as mandatory support for multitexture, better multitexture support (including 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.^[6] It is based roughly on OpenGL 2.0, but it eliminates most of the fixed-function rendering pipeline in favor of a programmable one in a move similar to transition from OpenGL 3.0 to 3.1.^[7] Control flow in shaders is generally limited to forward branching and to loops where the maximum number of iterations can easily be determined at compile time.^[8] Almost all rendering features of the transform and lighting stage, 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. Some incompatibilities between the desktop version of OpenGL and OpenGL ES 2.0 persisted until OpenGL 4.1, which added the GL_ARB_ES2_compatibility extension.^[9]

The Khronos Group has written a document describing the differences between OpenGL ES 2.0 and ordinary OpenGL 2.0.^[10]

OpenGL ES 3.0

The OpenGL ES 3.0 specification^[11] was publicly released in August 2012.^[12] OpenGL ES 3.0 is backwards compatible with OpenGL ES 2.0, enabling applications to incrementally add new visual features to applications. OpenGL 4.3 provides full compatibility with OpenGL ES 3.0. Version 3.0 is also the basis for WebGL 2.0.^[13]

New functionality in the OpenGL ES 3.0 specification includes:

• multiple enhancements to the rendering pipeline to enable acceleration of advanced visual effects including: occlusion queries, transform feedback, instanced rendering and support for four or more rendering targets,
• high quality ETC2 / EAC texture compression as a standard feature, eliminating the need for a different set of textures for each platform,
• a new version of the GLSL ES shading language^[14] with full support for integer and 32-bit floating point operations;
• greatly enhanced texturing functionality including guaranteed support for floating point textures, 3D textures, depth textures, vertex textures, NPOT textures, R/RG textures, immutable textures, 2D array textures, swizzles, LOD and mip level clamps, seamless cube maps and sampler objects,
• an extensive set of required, explicitly sized texture and render-buffer formats, reducing implementation variability and making it much easier to write portable applications.

OpenGL ES 3.1

The OpenGL ES 3.1 specification^[15] was publicly released in March 2014. New functionality in OpenGL ES 3.1 includes:^[16]

• Compute shaders
• Independent vertex and fragment shaders
• Indirect draw commands

OpenGL ES 3.1 is backward compatible with OpenGL ES 2.0 and 3.0, thus enabling applications to incrementally incorporate new features.

OpenGL ES 3.2

The OpenGL ES 3.2 specification^[17] was publicly released in August 2015. New capabilities in OpenGL ES 3.2 include:

• Geometry and tessellation shaders to efficiently process complex scenes on the GPU.
• Floating point render targets for increased flexibility in higher precision compute operations.
• ASTC compression to reduce the memory footprint and bandwidth used to process textures.
• Enhanced blending for sophisticated compositing and handling of multiple color attachments.
• Advanced texture targets such as texture buffers, multisample 2D array and cube map arrays.
• Debug and robustness features for easier code development and secure execution.

Platform usage

For complete list of companies and their conformant products, view here

OpenGL ES 1.0

OpenGL ES 1.0 added an official 3D graphics API to the Android^[18] and Symbian^[19] operating systems, as well as by QNX^[20] It is also supported by the PlayStation 3 as one of its official graphics APIs^[21] (the other one being low level libgcm library) with Nvidia's Cg in lieu of GLSL.^[22] The PlayStation 3 also includes several features of the 2.0 version of OpenGL ES.

OpenGL ES 1.1

The 1.1 version of OpenGL ES is supported by:

• Android 1.6
• Apple iOS for iPad, iPhone, and iPod Touch
• RIM's BlackBerry 5.0 operating system series^[23] (only BlackBerry Storm 2, BlackBerry Curve 8530 and later models have the needed hardware^[24])
• BlackBerry PlayBook
• BlackBerry BB10
• Various Nokia phones such as Nokia N95, N93, N93i, and N82.
• The Palm webOS, using the Plug-in Development Kit^[25]
• Nintendo 3DS^[26]

OpenGL ES 2.0

Supported by:

• The Android platform since Android 2.0 through NDK and Android 2.2 through Java^[27]
• AmigaOS on AmigaOne with Warp3D Nova and compatible RadeonHD graphics card.
• Apple iOS 5 or later in iPad, iPad Mini, iPhone 3GS or later, and iPod Touch 3rd generation or later
• BlackBerry devices with BlackBerry OS 7.0 and Blackberry 10, as well as the BlackBerry PlayBook
• Google Native Client
• Various Nokia phones (such as Symbian^3 based Nokia N8, MeeGo based Nokia N9, and Maemo based Nokia N900^[28])
• Palm webOS, using the Plug-in Development Kit^[25]
• The Pandora console
• The Raspberry Pi
• The Odroid
• Various Samsung mobile phones (such as the Wave)
• Web browsers (WebGL)
• The GCW Zero console

OpenGL ES 3.0

Supported by:

• Android since version 4.3, on devices with appropriate hardware and drivers, including:
  • Nexus 7 (2013)
  • Nexus 4
  • Nexus 5
  • Nexus 10
  • HTC Butterfly S
  • HTC One/One Max
  • LG G2
  • LG G Pad 8.3
  • Samsung Galaxy J5
  • Samsung Galaxy J5 (2016)
  • Samsung Galaxy S4 (Snapdragon version)
  • Samsung Galaxy S5
  • Samsung Galaxy Note 3
  • Samsung Galaxy Note 10.1 (2014 Edition)
  • Sony Xperia M
  • Sony Xperia Z/ZL
  • Sony Xperia Z1
  • Sony Xperia Z Ultra
  • Sony Xperia Tablet Z
• iOS since version 7, on devices including:
  • iPhone 5S^[29]
  • iPad Air
  • iPad mini with Retina display
• BlackBerry 10 OS since version 10.2, on devices including:
  • BlackBerry Z3
  • BlackBerry Z30
  • BlackBerry Passport

Supported by some recent versions of these GPUs:^[30][31]

• Adreno 300 and 400 series (Android, BlackBerry 10, Windows Phone 8, Windows RT)
• Mali T600 series onwards (Android, Linux, Windows 7)
• PowerVR Series6 (iOS, Linux)
• Vivante (Android, OS X 10.8.3, Windows 7)
• Nvidia (Android, Linux, Windows 7)
• Intel (Linux)

OpenGL ES 3.1

Supported by Windows, Linux, Android (since version 5.0) on devices with appropriate hardware and drivers,^[32] including:

• Adreno 400 series^[33][34]
• Intel HD Graphics for Intel Atom Z3700 series (Android)
• Intel HD Graphics for Intel Celeron N and J series (Android)
• Intel HD Graphics for Intel Pentium N and J series (Android)
• Mali T6xx (midgard) series onwards^[35] (Android, Linux)
• Nvidia GeForce 400 series onwards (Windows, Linux)
• Nvidia Tegra K1 (Android, Linux)
• Nvidia Tegra X1 (Android)
• PowerVR Series 6, 6XE, 6XT, 7XE and 7XT (Linux, Android)
• Vivante GC2000 series onwards (optional with GC800 and GC1000)^[36]

Android Extension Pack

Android Extension Pack is a set of OpenGL ES 3.1 extensions, all bundled into a single extension introduced by Google in 2014. This allows applications to use all of the features of the set of extensions, while only testing for the presence of a single one. The AEP was officially added to Android Lollipop to provide extra features like tessellation over what was officially in the GLES 3.1 revision. OpenGL ES 3.2 update is largely made up of the AEP additions, which are already present in desktop OpenGL.^[37]

OpenGL ES 3.2

OpenGL ES 3.2 works mostly on the same hardware as OpenGL 3.1. It incorporates Android Extension Pack (AEP) into it: "OpenGL ES 3.2 boasts a small number of improvements over last year’s OpenGL ES 3.1. Both make use of similar features from the AEP. From the AEP, OpenGL ES 3.2 compliant hardware will support Tessellation for additional geometry detail, new geometry shaders, ASTC texture compression for a smaller memory bandwidth footprint, floating point render targets for high accuracy compute processes, and new debugging features for developers. These high-end features are already found in the group’s full OpenGL 4 specification."^[38][3]

Supported by Windows, Linux, Android (since version 6.0) on devices with appropriate hardware and drivers, including:

• Adreno 420 and newer (Android)
• Mali-T760 and newer (Android)
• Nvidia GeForce 400 series (Fermi) and newer (Windows, Linux)^[39]

OpenGL compatibility

For full compatibility with OpenGL on ES-only devices, Nvidia offers a BSD licensed library called Regal, originally started by Cass Everitt.^[40] Regal is used for example by Google's NaCl.^[41]

See also

• Direct3D
• DirectX
• OpenGL – original cross-language, multi-platform API for rendering 2D and 3D vector graphics
• OpenSL ES – API for audio on embedded systems, developed by the Khronos Group
• Vulkan – low-level, cross-platform 2D and 3D graphics API, the "next generation OpenGL initiative"
• WebGL – Web Graphics Library is a JavaScript API for rendering 3D graphics within any compatible web browser without the use of plug-ins.

References

Further reading

• Ginsburg, Dan; Purnomo, Budirijanto; Shreiner, Dave; Munshi, Aaftab (2014). OpenGL ES 3.0 Programming Guide. Addison-Wesley Professional. ISBN 0-321-93388-5. 
• Pulli, Kari; Aarnio, Tomi; Miettinen, Ville; Roimela, Kimmo & Vaarala, Jani (2007). Mobile 3D Graphics with OpenGL ES and M3G. Morgan Kaufmann. ISBN 0-12-373727-3. 
• Astle, Dave & Durnil, David. OpenGL ES Game Development. Course Technology PTR. ISBN 1-59200-370-2. 
• Pulli, Kari; Aarnio, Tomi; Roimela, Kimmo & Vaarala, Jani. Designing graphics programming interfaces for mobile devices. IEEE CG&A 2005. 

External links

Wikibooks has a book on the topic of: OpenGL Programming/OpenGL ES Overview

• Official website
• Public bug tracking
• OpenGL ES Conformant companies
• Public forums
• List of OpenGL ES compatible devices
• OpenGL home page
• ANGLE: Almost Native Graphics Layer Engine, OpenGL ES 2.0 implementation on top of Direct3D 9/11
• OpenGL ES 1.1 & 2.0 Emulator from ARM
• OpenGL ES 3.0 Emulator from ARM