OpenGL FAQs

What is OpenGL?

OpenGL(R) is the software interface for graphics hardware that allows graphics programmers to produce high-quality color images of 3D objects. OpenGL is a rendering only, vendor neutral API providing 2D and 3D graphics functions, including modelling, transformations, color, lighting, smooth shading, as well as advanced features like texture mapping, NURBS, fog, alpha blending and motion blur.

OpenGL works in both immediate and retained (display list) graphics modes. OpenGL is window system and operating system independent. OpenGL has been integrated with Windows NT and with the X Window System under UNIX. Also, OpenGL is network transparent. A defined common extension to the X Window System allows an OpenGL client on one vendor's platform to run across a network to another vendor's OpenGL server.

What does the .gl or .GL file format have to do with OpenGL?

.gl files have nothing to do with OpenGL, but are sometimes confused with it. .gl is a file format for images, which has no relationship to IRIS GL or OpenGL.

Where can I get the OpenGL specification?

A PostScript version of OpenGL specification, along with the OpenGL Utility Library and GLX protocol specifications, are available via anonymous, public ftp, on the machine sgigate.sgi.com in ftp/pub/opengl/doc. They are all in the file, specs.tar.Z, which has been tar'd and compressed. The man pages for the OpenGL API, its Utility Library (GLU), and the X server extension API (GLX) are also here.

Please read the accompanying README file, which explains the copyright and trademark rules for usage of the specification.

Possession of the OpenGL Specification does not grant the right to reproduce, create derivative works based on or distribute or manufacture, use or sell anything that embodies the specification without an OpenGL license from SGI.

An HTML version of the OpenGL specification can be found on http://www.sgi.com/Technology/openGL/glspec/glspec.html

An HTML version of the OpenGL man pages can be found on http://www.digital.com:80/pub/doc/opengl/

Which vendors are licensing OpenGL?

OpenGL is supported by many hardware and software vendors. As of September, 1995, OpenGL has been licensed to:

• 3Dlabs
• AT&T
• AccelGraphics
• Cirrus Logic
• Cray Research
• Daikin
• Digital Equipment
• Division
• Dynamic Pictures
• Evans & Sutherland
• HP
• Harris Computer
• Hitachi
• IBM
• Intel
• Intergraph
• Japan Radio Co.
• Kendall Square Research
• Media Vision
• Metro Link
• Microsoft
• Miro
• NCD
• NEC
• NeTpower
• Peritek
• Portable Graphics
• SPEA
• Samsung
• Sony
• SunSoft
• Template Graphics Software
• The Institute for Information Industry
• Univel

Who needs to license OpenGL? Who doesn't?

Companies which will be creating or selling binaries of the OpenGL library will need to license OpenGL. Typical examples of licensees include hardware vendors, such as Digital Equipment, and IBM who would distribute OpenGL with the system software on their workstations or PCs. Also, some software vendors, such as Portable Graphics and Template Graphics, have a business in creating and distributing versions of OpenGL, and they need to license OpenGL.

Applications developers do NOT need to license OpenGL. If a developer wants to use OpenGL, that developer needs to obtain copies of a linkable OpenGL library for a particular machine. Those OpenGL libraries may be bundled in with the development and/or run-time options or may be purchased from a third-party software vendor, without licensing the source code or use of the OpenGL(R) trademark.

Since many implementations will be a shared library on a hardware platform, the royalty sometimes will be charged for each hardware platform. In those cases, it would not be charged for each application which used OpenGL.

In general, licensing a source code implementation of OpenGL would not be useful for an application developer, because the binary created from that implementation would not be accelerated and optimized to run on the graphics hardware of a machine.

What are the conformance tests?

The conformance tests are a suite of programs which judge the success of an OpenGL implementation. Each implementor is required to run these tests and pass them in order to call their implementation with the registered trademark OpenGL. Passing the conformance tests ensures source code compatibility of applications across all OpenGL implementations.

What is Silicon Graphics policy on "free" implementations of APIs which resemble the OpenGL API?

Silicon Graphics, as licensor of the OpenGL(R) trademark, does not permit non-licensed use of the OpenGL trademark, nor does it permit non-licensed use of the OpenGL conformance tests. Silicon Graphics provides a source code sample implementation of OpenGL, but only to companies and organizations which agree to the terms and conditions of an OpenGL license.

Silicon Graphics does give permission to others to create and distribute their own implementations of the OpenGL API, provided they do not state nor imply they have the right to use the OpenGL(R) trademark to name their product, nor make claims to conformance based upon the ARB controlled OpenGL conformance tests. Silicon Graphics agrees to allow others to copy the OpenGL header files, as much as is necessary, for the creation of other implementations.

Silicon Graphics is in no way associated nor endorsing these other graphics libraries. Silicon Graphics does not make any claims or guarantees as to the quality, performance, nor completeness of an unlicensed library.

How does a university or research institution acquire access to OpenGL source code?

There is a university/research institution licensing program. A university license entitles the institution to generate binaries and copy them anywhere, so long as nothing leaves the institution. The OpenGL source and derived binaries can only be used for non-commercial purposes on-campus.

A university license costs $500 US. This license provides source code for a sample implementation of OpenGL. This source code is best designed for porting onto a system which supports the X Window System. You can drop this into the X Consortium's X11 server source tree and build a server with the OpenGL extension. To do this properly, you should have the MIT source for an X Server and some experience modifying it.

Note that this gets you a software renderer only. If your machine includes a graphics accelerator, the sample implementation is not designed to take any advantage of it.

To obtain a university license, contact John Schimpf, OpenGL Licensing Manager at Silicon Graphics (jsch@sgi.com). Please provide a mailing address, telephone and fax number.

Universities may also be interested in Mesa 3D. See Q12.

How is a commercial license acquired?

If you need a license or would like more information, call John Schimpf at (415)390-3062 or e-mail him at jsch@sgi.com. There are licenses available restricted to site (local) usage, or permitting redistribution of binary code. The limited source license provides a sample implementation of OpenGL for $50,000. The license for commerical redistribution of OpenGL binaries has two most commonly chosen levels. Level 1 costs $25,000. Level 2 costs $100,000, and includes the sample implementation of OpenGL.

Both levels require a $5 royalty for every copy of the OpenGL binary, which is redistributed.

How is the OpenGL governed? Who decides what changes can be made?

OpenGL is controlled by an independent board, the Architecture Review Board (ARB). Each member of the ARB has one vote. The permanent members of the ARB are Digital Equipment, IBM, Intel, Microsoft, and Silicon Graphics. Additional members will be added over time. The ARB governs the future of OpenGL, proposing and approving changes to the specification, new releases, and conformance testing.

Who are the current ARB members?

In alphabetical order: Digital Equipment, Evans & Sutherland, IBM, Intel, Intergraph, Microsoft, and Silicon Graphics.

What is the philosophy behind the structure of the ARB?

The ARB is intended to be able to respond quickly and flexibly to evolutionary changes in computer graphics technology. The ARB is currently "lean and mean" to encourage speedy communication and decision-making. Its members are highly motivated in ensuring the success of OpenGL.

How does the OpenGL ARB operate logistically? When does the ARB have meetings?

ARB meetings are held about once a quarter. The meetings rotate among sites hosted by the ARB members. To learn the date and place of the next OpenGL ARB meeting, watch the news group comp.graphics.opengl for posting announcing the next "OpenGL ARB meeting", check the Web site http://www.sgi.com/Technology/openGL/arb.location.html or e-mail opengl-secretary@sgi.com and ask for the information.

Meetings are run by a set of official by-laws. A copy of the by-laws may be requested from the Secretary of the OpenGL ARB.

Minutes to the ARB meeting are posted to comp.graphics.opengl and are available via ftp://sgigate.sgi.com/pub/opengl/arb/

How do additional members join the OpenGL ARB?

The intention is that additional members may be added on a permanent basis or for a one-year term. The one-year term members would be voting members, added on a rotating basis, so that different viewpoints (such as ISV's) could be incorporated into new releases. Under the by-laws, SGI formally nominates new members.

So if I'm not a member of the ARB, am I shut out of the decision making process?

There are many methods by which you can influence the evolution of OpenGL.

1) Contribute to the comp.graphics.opengl news group. Most members of the ARB read the news group religiously.

2) Contact any member of the ARB and convince that member that your proposal is worth their advocacy. Any ARB member may present a proposal, and all ARB members have equal say.

3) Come to OpenGL ARB and speak directly to ARB.

Are ARB meetings open to observers?

The ARB meeting will be open to observers, but we want to keep the meeting small. Currently, up to five non-voting representatives who inform the ARB secretary in advance, can observe and participate in the ARB meeting. At any time, the ARB reserves the right to change the number of observers.