OpenGL ES

OpenGL for Embedded Systems (OpenGL ES or GLES) is a subset 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".

The API is cross-language and multi-platform. The GLU library and the original GLUT are not available for OpenGL ES, freeglut however, supports it. 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.

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.[unreliable source?]

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 1.3 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 operations, bitmaps, and 3D textures are not supported;
  • several of the more technical drawing modes are eliminated, including frontbuffer and accumulation buffer;
  • bitmap operations for copying pixels individually, evaluators, and user selection operations are not allowed;
  • display lists and feedback are removed, as are push and pop operations for state attributes;
  • and some material parameters were removed, including back-face parameters and user-defined clip planes.

The actual version is 1.0.0.2.

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. Actual Version is 1.1.12.

OpenGL ES 2.0

OpenGL ES 2.0 was publicly released in March 2007. It is roughly based 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 the transition from OpenGL 3.0 to 3.1. 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. 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. Actual version is 2.0.25.

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

OpenGL ES 3.0

The OpenGL ES 3.0 specification was publicly released in August 2012. It is backwards compatible with OpenGL ES 2.0, and partially compatible with WebGL 2.0, as WebGL 2.0 was designed to have a high degree of interoperability with OpenGL ES 3.0. The current version of the OpenGL ES 3.0 standard is 3.0.6, released in November 2019.

New functionality in the OpenGL ES 3.0 specification includes:

OpenGL ES 3.1

The OpenGL ES 3.1 specification was publicly released in March 2014. New functionality in OpenGL ES 3.1 includes:

  • 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. Actual Version is 3.1-(November 2016).

OpenGL ES 3.2

The OpenGL ES 3.2 specification 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.

Actual State is 3.2.6 July 2019.

Some more extensions are developed or in Development in Mesa for next OpenGL ES Version (see Mesamatrix).

Next generation API is Vulkan.

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 and Symbian OS v8.0a operating systems, as well as by QNX It is also supported by the PlayStation 3 as one of its official graphics APIs (the other one being low level libgcm library) with Nvidia's Cg in lieu of GLSL. 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:

OpenGL ES 2.0

Supported by:

OpenGL ES 3.0

Supported by:

Supported by some recent versions of these GPUs:

  • Adreno 300 and 400 series (Android, BlackBerry 10, Windows10 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), Tesla G80+: Linux, Windows 7+
  • Intel HD Graphics Sandy Bridge and higher (Linux)
  • AMD Terascale and actual GCN-architecture (Windows, Linux)
  • LLVMpipe and Softpipe: soft drivers in Mesa
  • VIRGL: virtual Driver for virtual machines in 2018 with Mesa 18.1 (See Mesamatrix.net)

OpenGL ES 3.1

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

  • Adreno 400 series
  • Adreno 500 series (Mesa 18.1 for Linux and Android)
  • AMD Terascale and actual GCN-architecture (Windows, Linux (r600, radeonSI))
  • 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)
  • Intel HD Graphics Haswell and higher (Linux Mesa: previous Ivy Bridge nearly without stencil texturing)
  • Mali T6xx (midgard) series onwards (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)
  • panfrost: ARM panfrost support (Linux Mesa 22.0)
  • v3d: Driver for Broadcom VideoCore in Mesa (Linux)
  • VIRGL: virtual Driver for virtual machines in 2018 with Mesa 18.1 (See Mesamatrix.net)
  • LLVMpipe: software driver in Mesa 20.2 (Linux)
  • softpipe: software driver in Mesa 20.3 (Linux)
  • Zink: emulation driver in Mesa 21.1 (Linux)
  • d3d12: WSL2 linux driver for Microsoft 10+ (Mesa 22.0)
  • Apple M1 and M2 graphics in Fedora Asahi Remix (Linux)

Android Extension Pack

Android Extension Pack (AEP) 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.

OpenGL ES 3.2

OpenGL ES 3.2 usage on a Linux system (with AMDGPU)

OpenGL ES 3.2, incorporating the Android Extension Pack (AEP), "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."

Supported by Windows, Linux, Android (since version 6.0 possible, 7.0+ Vulkan 1.0 and OpenGL ES 3.2 needed) on devices with appropriate hardware and drivers, including:

  • Adreno 420 and newer (Android, Linux (freedreno))
  • AMD GCN-architecture (Windows, Linux (Mesa 18.2 with radeonSI))
  • Intel HD Graphics Skylake and higher (Linux)
  • Mali-T760 and newer (Android, Linux)
  • Nvidia GeForce 400 series (Fermi) and newer (Windows, Linux)
  • VIRGL: virtual Driver for virtual machines in 2018 with Mesa 18.1 (See Mesamatrix.net)
  • LLVMpipe: software driver in Mesa 20 (Linux)
  • Zink: Vulkan emulation driver in Mesa 21.2 (Linux)

Deprecation in Apple platforms

OpenGL ES (and OpenGL) was deprecated in Apple's operating systems in favour of its own proprietary Metal graphics API, but still worked in up to at least iOS 12.

The future

There is currently no plan for a new core version of OpenGL ES, as adoption of Vulkan has been deemed to displace it in embedded and mobile applications. Development of extensions to OpenGL ES continues as of 2017.

OpenGL compatibility

A few libraries have been created to emulate OpenGL calls using GL ES:

  • Nvidia offers a 2-clause BSD licensed library called Regal, originally started by Cass Everitt. It was last updated in 2016. Regal is used for example by Google's NaCl.
  • The MIT licensed GL4ES emulates OpenGL 2.1/1.5 using GL ES 2.0/1.1. It is based on glshim.

See also

References

Further reading

  • Ginsburg, Dan; Purnomo, Budirijanto; Shreiner, Dave; Munshi, Aaftab (2014). OpenGL ES 3.0 Programming Guide. Addison-Wesley Professional. ISBN 978-0-321-93388-1.
  • Pulli, Kari; Aarnio, Tomi; Miettinen, Ville; Roimela, Kimmo & Vaarala, Jani (2007). Mobile 3D Graphics with OpenGL ES and M3G. Morgan Kaufmann. ISBN 978-0-12-373727-4.
  • Astle, Dave & Durnil, David (2004). OpenGL ES Game Development. Course Technology PTR. ISBN 1-59200-370-2.
  • Pulli, Kari; Aarnio, Tomi; Roimela, Kimmo & Vaarala, Jani (2005). "Designing graphics programming interfaces for mobile devices". IEEE Computer Graphics and Applications. 25 (6). IEEE CG&A 2005: 66–75. doi:10.1109/MCG.2005.129. PMID 16315479. S2CID 8177273.
Uses material from the Wikipedia article OpenGL ES, released under the CC BY-SA 4.0 license.