SGI Developer Toolbox 6.1/SGI Developer Toolbox 6.1 - Disc 1.iso/toolbox/FAQs/SGIfaqs/OpenGL-faq

Text File | 1996-11-11 | 35KB | 829 lines

From: [e-mail] (Mason Woo)
Newsgroups: comp.graphics.opengl,comp.answers,news.answers
Subject: comp.graphics.opengl Frequently Asked Questions (FAQ) [1/1]
Followup-To: poster
Date: 16 Dec 1994 18:16:03 GMT
Organization: Silicon Graphics Inc., Mountain View, CA
Lines: 808
Approved: [e-mail]
Distribution: world
Expires: 31 January 1995 00:00:00 GMT
Message-ID: <3cslh3$[e-mail]>
Reply-To: [e-mail]
NNTP-Posting-Host: kicksave.asd.sgi.com
Summary: This contains a list of Frequently Asked Questions about OpenGL (TM)
Keywords: FAQ
Xref: bloom-beacon.mit.edu comp.graphics.opengl:2870 comp.answers:8979 news.answers:31357

Archive-name: graphics/opengl-faq
Last-modified: 1994 December 1
Version: 1.26

This FAQ is posted twice a month, usually near the 1st and 15th of
every month.  You may also want to see the OpenGL Web Page:
WWW URL http://www.sgi.com/tech/openGL/opengl.html

   * marks recently modified answers or new questions

   Q1:  What is OpenGL?
   Q2:  What is the relationship between IRIS GL and OpenGL?
   Q3:  What does the .gl or .GL file format have to do with OpenGL?
   Q4:  Where are World Wide Web sites for OpenGL?
   Q5:  What documentation is available for OpenGL?  (A bibliography of OpenGL
    documents is listed here.)
    Where can I get the OpenGL specification?
   Q6:  Where can I find OpenGL source code examples?
    For instance, where can I find examples which mix OpenGL with Motif
    and use the Motif widget?
   Q7:  Which vendors are supporting OpenGL?
 * Q8:  What OpenGL implementations are available?
   Q9:  How do I contribute OpenGL code examples to a publicly accessible
    archive?
  Q10:  Will OpenGL code be source code or binary code compatible with IRIS GL
    code?
  Q11:  Why should I port my IRIS GL application to OpenGL?
  Q12:  How much work is it to convert an IRIS GL program to OpenGL?
    What are the major differences between them?
  Q13:  Who needs to license OpenGL?
    Who doesn't?
    How is a commercial license acquired?
  Q14:  How does a university or research institution acquire access to OpenGL
    source code?
  Q15:  Why doesn't SGI provide a free implementation of OpenGL?
  Q16:  What are the conformance tests?
  Q17:  How is the OpenGL governed?
    Who decides what changes can be made?
  Q18:  Who are the current ARB members?
  Q19:  What is the philosophy behind the structure of the ARB?
  Q20:  How does the OpenGL ARB operate logistically?
    When does the ARB have meetings?
  Q21:  How do additional members join the OpenGL ARB?
  Q22:  So if I'm not a member of the ARB, am I shut out of the decision
    making process?
  Q23:  Are ARB meetings open to observers?
  Q24:  What is the OpenGL Advisory Forum?

------
Subject:  Q1:  What is OpenGL?

A:  OpenGL 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.

------
Subject:  Q2:  What is the relationship between IRIS GL and OpenGL?

A:  IRIS GL is the predecessor to OpenGL.  After other implementors
had experience trying to port the IRIS GL to their own machines, it
was learned that the IRIS GL was too tied to a specific window system
or hardware.  Based upon consultations with several implementors,
OpenGL is much more platform independent.

IRIS GL is being maintained and bugs will be fixed, but SGI will no
longer add enhancements.  OpenGL is now the strategic interface for
3-D computer graphics.

------
Subject:  Q3:  What does the .gl or .GL file format have to do with OpenGL?

A:  .gl files have nothing to do with OpenGL.  It's a file format for
images, which has no relationship to IRIS GL or OpenGL.

------
Subject:  Q4:  Where are World Wide Web sites for OpenGL?

A:  OpenGL--The Integration of Windowing and 3D Graphics.
WWW URL http://hertz.eng.ohio-state.edu/~hts/opengl/article.html
Maintained by Harry Shamansky.

OpenGL WWW Center.
WWW URL http://www.sgi.com/tech/openGL/opengl.html
Maintained by Mason Woo.

------
Subject:  Q5:  What documentation is available for OpenGL?  (A
bibliography of OpenGL documents is listed here.)  Where can I
get the OpenGL specification?

A:  A 2 volume set, The OpenGL Technical Library (The OpenGL
Programming Guide and The OpenGL Reference Manual) is published
by Addison-Wesley.  The ISBN numbers for both English and
Japanese versions are listed below.  You can purchase the books
in extremely large volume by calling Robert Shepard of
Addison-Wesley [phone] ext 2435.

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

What follows is a bibliography of articles, books, and papers written
about OpenGL.

Books (in English)
------------------
Neider, Jackie, Tom Davis, and Mason Woo, OpenGL Programming
Guide:  The Official Guide to Learning OpenGL, Release 1,
Addison-Wesley, Reading, Massachusetts, 1993 (ISBN 0-201-63274-8).

OpenGL Architecture Review Board, OpenGL Reference Manual:  The
Official Reference Document for OpenGL, Release 1,
Addison-Wesley, Reading, Massachusetts, 1992 (ISBN 0-201-63276-4).

Magazine articles
-----------------
Bruno, Lee.  "Sun Continues to Resist OpenGL Tide," Open Systems Today,
November 28, 1994, p. SF1, SF5-6.

Davis, Tom.  "Moving to OpenGL," IRIS Universe, Number 25,
Summer, 1993.

Glazier, Bill.  "The 'Best Principle':  Why OpenGL is emerging as the 3D
graphics standard," Computer Graphics World, April, 1992.

"Industry group pushing 3-D graphics standard," Computer Design,
July, 1994, p. 50, 52.

Karlton, Phil.  "Integrating the GL into the X environment:  a
high performance rendering extension working with and not against
X,"  The X Resource:  Proceeding of the 6th Annual X Technical
Conference, O'Reilly Associates, Issue 1, Winter, 1992.

Kilgard, Mark, Simon Hui, Allen Leinwand, and Dave Spalding. ``X
Server Multi-rendering for OpenGL and PEX,'' The X Resource
Proceedings of the 8th Annual X Technical Conference, O'Reily
and Associates, Sebastopol, California, January 1994.

Kilgard, Mark J.  "OpenGL & X:  An Introduction,"  The X Journal.
November-December, 1993, page 36-51.

Kilgard, Mark J.  "Using OpenGL with Xlib,"  The X Journal.
January-February, 1994, page 46-65.

Kilgard, Mark J.  "Using OpenGL with Motif,"  The X Journal.
July-August, 1994.

"OpenGL Programs a New Horizon for Sun," SunWorld, January, 1994,
page 15-17.

Prosise, Jeff.  "Advanced 3-D Graphics for Windows NT 3.5:
Introducing the OpenGL Interface, Part I," Microsoft Systems Journal,
October, 1994, Vol. 9, Number 10, pages 15-29.

Japanese language magazine articles and books
---------------------------------------------
Nikkei Electronics, No. 616, Sept. 5, 1994, p. 99-105.

PIXEL, No. 143, 8/94, p. 65 ("From the Editor's Desk"),
p. 117-121 ("3D API, OpenGL").

Neider, Jackie, Tom Davis, and Mason Woo, OpenGL Programming
Guide:  The Official Guide to Learning OpenGL, Release 1,
Addison-Wesley Publishers Japan, Tokyo, 1993 (ISBN 4-7952-9645-6).

OpenGL Architecture Review Board, OpenGL Reference Manual:  The
Official Reference Document for OpenGL, Release 1,
Addison-Wesley Publishers Japan, Tokyo, 1992 (ISBN 4-7952-9644-8).

Technical reports
-----------------
Segal, Mark and Kurt Akeley.  The OpenGL Graphics System:  A
Specification.  Technical report, Silicon Graphics Computer
Systems, Mountain View, California, 1992, revised 1993.

Segal, Mark and Kurt Akeley.  The OpenGL Graphics Interface.
Technical paper, Silicon Graphics Computer Systems, Mountain
View, California, 1993.

------
Subject:  Q6:  Where can I find OpenGL source code examples?
Where can I find examples which mix OpenGL with Motif and use the
Motif widget?

You can get the source code examples which are found in the
OpenGL Programming Guide via anonymous, public ftp on
sgigate.sgi.com in the file ~ftp/pub/opengl/opengl.tar.Z

Mark Kilgard has created an ftp site for source code, which is
part of his articles in the X Journal magazine.  This includes
some OpenGL with Motif examples.  The directory is:

sgigate.sgi.com:~ftp/pub/opengl/xjournal
The following is an excerpt from the README file there:

This directory contains source code published in The X Journal's
three-part series on programming OpenGL with X.

   glxsimple.c - a simple OpenGL program using Xlib (the Part 1
      example).

   glxdino.c - a more complicated OpenGL program using Xlib that
      draws a rotatable 3D dinosaur (the Part 2 example).

   paperplane.c - an OpenGL program using Motif to draw flying
      paper planes (the Part 3 example).  It can be compiled to use
      either the standard Motif drawing area or the OpenGL-specific
      widgets.

   glxmotif.c - another OpenGL program using Motif.

   textfun.c - another OpenGL program using Motif that demonstrates
      the display of a crude 3D fonts.

glxmotif.c and textfun.c were not published in The X Journal.

------
Subject:  Q7:  Which vendors are supporting OpenGL?

A:  OpenGL is supported by many hardware and software vendors.
As of September, 1994, OpenGL has been licensed to:

AT&T, Cirrus Logic (which supports the A1060 technology, formerly from
Austek Microsystems), Cray Research, Daikin, Digital Equipment,
3Dlabs (formerly Du Pont Pixel; supporting the GLINT OpenGL chip),
Evans & Sutherland, Harris Computer, Hitachi, IBM,
the Institute for Information Industry, Intel, Intergraph,
Japan Radio Co., Kendall Square Research, Kubota Pacific,
Media Vision, Microsoft, miro, NEC, Portable Graphics (formerly
Nth Portable Graphics; supporting Sun and HP), RasterOps, SPEA,
Samsung, Sony, Template Graphics Software, and Univel.

The machines supported by OpenGL licensees constitute over 95% of
the graphics workstation marketplace, as well as the majority of
the PC market.

------
Subject:  Q8:  What OpenGL implementations are available?

A:


Digital (DEC)
------- -----
Digital Equipment Corporation offers OpenGL to its customers as part of the
the DEC Open3D layered product. DEC Open3D is available for DEC OSF/1 AXP and
DEC OpenVMS AXP workstations. Supported graphics devices include:
        PXG (all devices in the PXG family with z-buffers)
        ZLX-M1
        ZLX-M2
        ZLX-E1
        ZLX-E2
Digital Equipment Corporation will be supporting OpenGL on Windows NT in the
near future. Digital Equipment Corporation at this time has no plans to offer
Open3D on either VAXstations or DECstations.
For further information contact your Digital Equipment sales representative.

IBM
---
IBM offers OpenGL 1.0 at several different price and performance points,
on most configurations of it's RS/6000 workstation line.  Hardware
accelerated OpenGL is available through two recently announced products:
the mid-range POWERgraphics GXT1000 and the high-end Freedom Series /6000.
Both platforms provide h/w support for texture mapping, accumulation,
stencil and alpha buffers, as well as a h/w accelerated lighting and
geometry transformation pipeline. The Freedom Series is based on an
architecture developed by Evans and Sutherland.

OpenGL is supported on most other RS/6000 configurations, including
the GXT100 and GXT150 graphics adapters for the PowerPC-based /6000's
as well as on the CGDA, the Gt1 family, the Gt3 family, and the Gt4
family of graphics adapters.  This support is provided through
SoftGraphics, a highly-tuned, highly-optimized pure software
implementation of OpenGL.  (Because of the lack of support for an
RGB X11 TrueColor visual on the 3D-HP-CGP and GTO adapters, OpenGL
is not offered on these machines. This is the only exception to
OpenGL support on the RS/6000 line. Sorry). OpenGL requires AIX 3.2.5
or later.

At the Fall '93 Comdex, IBM exhibited a software technology
that allowed OpenGL to run under OS/2.  The interface that
integrates OpenGL with OS/2 was presented to the OpenGL ARB for
review. Beta versions of that interface will be available in the
first half of 1994, through the OS/2 Developer CD-ROM distribution.

To purchase these products, contact your local IBM sales office.

Intergraph
----------
Intergraph Computer Systems is currently shipping high-performance, PCI-based,
OpenGL accelerators on its TD series of Personal Workstations.  Using state of
the art dedicated hardware, the GLZ and GLI graphics products dramatically
accelerate OpenGL and offer the high performance and features traditionally
found only on much more expensive workstations.  These accelerators are
available on Intergraph's TD-4 and TD-5 dual-Pentium Personal Workstations
running Windows NT.

GLZ and GLI offer advanced features such as:

     - 24-bit, double buffered image planes at all display resolutions up to
       2 Mpixels
     - 24-bit (GLZ) or 32-bit (GLI) Z-Buffer
     - Full hardware support for Gouraud shading
     - Full hardware support for texture processing (GLI only) with 8
       MTexels of texture storage
     - Industry-standard PCI bus interface with DMA engine
     - Support for multi-sync monitors up to 2 Mpixels at 76Hz vertical
       refresh
     - Stereo ready
     - Multiple color palette support
     - 10-bit gamma correction

For additional information call 1 [phone] or browse Intergraph's WWW
pages at http://www.intergraph.com.

Microsoft
---------
OpenGL is offered as a standard feature of Microsoft Windows NT
Workstation version 3.5.   The Microsoft implementation of OpenGL runs
with any computer and video hardware that is compatible with Windows NT
3.5.  Microsoft also provides documentation, sample source code, and
development tools to help build OpenGL applications in the Win32
Software Development Kit.   The Win32 SDK is available via Microsoft's
Developer Network.

For more information on the Win32 SDK, please call:
        US at 1-800-759-5474
        International at [phone]

Portable Graphics, Inc.
----------------------------------------------------------
3D Graphics Development and Porting Tools

Portable Graphics, a wholly owned subsidiary of Evans & Sutherland Computer
Corporation, provides GL-based development and porting solutions for a
variety of workstation platforms.  Products for Windows NT and Windows are
planned for early 1995.

OpenGL:

Portable Graphics currently supplies OpenGL for Sun SPARCstation
workstations. OpenGL for HP is in development for release in early 1995.
OpenGL for Sun is an interoperable, conformance-compliant implementation of
OpenGL that is optimized for the SPARC/Solaris environment.  It supports the
speed and graphics capabilities of all SMCC and third-party graphics
accelerators through XGL.  OpenGL can coexist with a PHIGS, PEX, or NPGL
(IRIS GL 4.0-compatible) applications on the same device. Portable Graphics
supplies the GLU library, and widget sets for both Motif and OPEN LOOK.

OpenGL requires Solaris 2.4, XGL 3.x, a color monitor, and any current or
future graphics accelerator supported by XGL. These include the GX, GXplus,
TurboGXplus, GS, SX and ZX.

Developers who wish to develop OpenGL and Open Inventor applications for HP
workstations can get started now using NPGL and IRIS Inventor.  Theses
applications can then be converted to OpenGL and Open Inventor when Portable
Graphics releases these products for HP in early 1995.

Portable Graphics offers custom OpenGL ports for PC and workstation graphics
accelerator manufacturers, and consulting services to hardware manufacturers
and software developers.

Open Inventor - 3D Developer's Toolkit:

Portable Graphics also licenses Open Inventor from Silicon Graphics.  Open
Inventor is currently available on the IBM RISC System/6000, and will soon
be released for Sun SPARCstation systems.  Portable Graphics will also
provide Open Inventor for HP Series 700 workstations, Evans & Sutherland
Freedom Series accelerators for HP, IBM and Sun workstations, and Windows
NT/Windows.  Portable Graphics offers IRIS Inventor for HP and Sun
workstations.

EDISON - Extensions to Open Inventor:

Portable Graphics is currently developing extensions to Open Inventor.  The
product, which is called EDISON, will provide the framework to seamlessly
link other software modules to Open Inventor.  The first extension released
under EDISON will be the SHAPES Geometric Modeling System from XOX
Corporation (Minneapolis, MN). By combining SHAPES and Open Inventor via
EDISON, developers will obtain a powerful geometric computing system based
on mathematical standards that also features an easy-to-use, interactive
user interface and graphics rendering capabilities. The EDISON extensions to
Open Inventor will be available in early 1995 for Silicon Graphics
workstations, followed by support for Sun, IBM, and HP workstations, and
Windows NT/Windows.

For more information about OpenGL, Open Inventor, EDISON extensions to Open
Inventor, IRIS Inventor, or NPGL, contact:

Portable Graphics, Inc.
One Technology Center
2201 Donley Drive, Suite 365
Austin, TX 78758

E-mail: [e-mail]
Voice:  [phone]
Fax:  [phone]


Silicon Graphics
---
Starting with IRIX 5.2 OpenGL will be supported for the following graphics
workstations:

    Indy - Indy 8/24 bits
    Indigo - Entry Level, XS, XS24, XZ, Elan
    Indigo2 - XL, XZ, Extreme
    Crimson - Entry Level, XS, XS24, Elan, Extreme, RealityEngine
    Onyx - VTX, RealityEngine, RealityEngine2
    4D30/35 - Elan

Silicon Graphics is currently beta-testing OpenGL libraries for these
platforms:

    Personal IRIS Graphics: 8-bit, G, TG (except GR1.1)
    VGX, VGXT, Skywriter

This leaves the following graphics families with no OpenGL implementation:

    IRIS 1000, 2000, and 3000 series
    IRIS 4D/G, GT, GTX
    Personal IRIS GR1.1 (suggest purchasing graphics board upgrade to GR1.2)

Sony
----
Sony offers OpenGL on the complete range of its RISC based NEWS
workstations.  Sony OpenGL requires NEWS OS 6.0.1 and later.
This is a pure software implementation.

Starting in September 1994, Sony have hardware support for OpenGL
on its 3D graphics workstations:  on the NWS-5000G and the 3D
graphics acceleration card NWB-1501 for NWS-5000 series
workstations.

Template Graphics Software, Inc. (TGS)
--------------------------------------
The Standard in Graphics Tools

* OpenGL - Accelerated to Hardware (Sun, Apple, Microsoft Windows 3.1)

TGS is providing OpenGL direct to Sun SPARC Solaris 2.x acceleration
hardware.  This differs from other software-only products in that it
avoids the additional XGL software layer.  The result is a fast
performing and fully functional OpenGL for Sun workstations and
clone systems.  (OpenGL for Solaris from TGS was recently selected by
Aries Research as the OpenGL to be sold with their SPARC systems.)

OpenGL for Solaris from TGS supports the ZX, GX, GX+, TGX, TGX+ graphics
boards and can render in software if a graphics board is not installed
on your system.  TGS also supports the GLX server extension on Solaris.
OpenGL for Solaris from TGS is available today in beta.

TGS will also be providing OpenGL for Apple Power Macintosh in early 1995,
with a software-rendering and graphics acceleration version.  TGS is
working with 3D chip/board vendors to deliver accelerated OpenGL for
the Power Mac platform.

TGS is now providing OpenGL for Windows 3.1, direct to GDI, to ISV and
OEM customers.  OpenGL for Windows 3.1 is fully portable with the
OpenGL for Windows NT 3.5 provided by Microsoft, including the WGL
component.

* Open Inventor - C++ 3D Graphics Toolkit

TGS will be a single-stop solution for Open Inventor on UNIX and
PC systems.  TGS is currently shipping Open Inventor for IBM AIX and Sun
Solaris, and will support DEC (1Q95) and HP (1-2Q95) UNIX systems as well.
TGS will deliver Open Inventor for Visual C++/MFC beginning in 1Q95, and
will support MS-Visual C++ on Windows 3.1, Windows NT, Windows 95 and
the new MS-Visual C++ Apple cross-compiler.  Contact TGS for further
information on these products as well as other Open Inventor ports.

* Sales and Support

TGS has supported ISV's and professional graphics software developers since
1982 from our San Diego headquarters.  TGS has regional sales offices in
San Jose, Houston, Atlanta and Boston, with European headquarters in the U.K.

For additional information on TGS graphics software:

        Template Graphics Software
        9920 Pacific Heights Blvd. #200
        San Diego, CA 92121

        WWW = http://www.sd.tgs.com/~template
        [e-mail]

        Robert J. Weideman, V.P. Marketing
        [phone] x229
        [phone] (fax)
        [e-mail]


3Dlabs
------
3Dlabs Inc. (formerly Du Pont Pixel) announced that they will be providing
a direct implementation of OpenGL to run on their GLINT graphic processor.
Available Q4 94.  For further information contact 3Dlabs at [phone].

SGI does not speak for any other company.  However, this space is
available for any company who wishes to state status reports or
release dates for their OpenGL implementation.  Please send e-mail
to [e-mail] to add to this section.

------
Subject:  Q9:  How do I contribute OpenGL code examples to a publicly
accessible archive?

A:  To contribute to the public OpenGL archive, send mail to
[e-mail].  Your mail should contain:

    The material to be archived, or instructions for obtaining it.

    An announcement suitable for posting to comp.graphics.opengl.

SGI will place the material in the OpenGL/contrib directory on
sgigate.sgi.com and post the announcement to this newsgroup.

To retrieve something from the archive, use anonymous ftp to
sgigate.sgi.com.  Once connected, cd to the directory OpenGL.
(Case is significant.)  Currently there are two subdirectories:

    doc
        Manual pages for OpenGL and related libraries.

    contrib
        Contributions from the public.

Note that all contributions are distributed as-is; neither SGI nor the
other companies on the OpenGL Architecture Review Board make any
legally valid claims about the robustness or usefulness of this software.

If you do not have access to anonymous ftp, consider using an
"ftp-by-mail" server.  For information on one such server, send mail
to [e-mail] with a message body containing only the word
"help".


------
Subject:  Q10:  Will OpenGL code be source code or binary code compatible with
IRIS GL code?

A:  OpenGL code is neither binary nor source code compatible with IRIS
GL code.  It was decided to bite the bullet at this time to make
OpenGL incompatible with IRIS GL and fix EVERYTHING that made IRIS GL
difficult to port or use.  For example, the gl prefix has been added
to every command:  glVertex(), glColor(), etc.

------
Subject:  Q11:  Why should I port my IRIS GL application to OpenGL?

SGI will be maintaining the old IRIS GL, but not enhancing it.
OpenGL is the API of choice on all new SGI machines.

OpenGL has no subsets.  You can use the same functionality
on all machines from SGI or from other vendors.

OpenGL is better integrated with the X Window System than
the old IRIS GL.  For example, you can mix OpenGL and X
or Display PostScript drawing operations in the same window.

The OpenGL naming scheme, argument list conventions, and
rendering semantics are cleaner than those of IRIS GL.  This
should make OpenGL code easier to understand and maintain.

------
Subject:  Q12: How much work is it to convert an IRIS GL program to OpenGL?
What are the major differences between them?

There is a fair amount of work, most of which is in substituting
for window management or input handling routines, for which the
equivalents are not OpenGL, but the local window system, such as
the X Windows System or Windows NT.  And all routine names have changed,
at least, minimally; for example:  ortho() is now glOrtho().

To help ease the way, port to "mixed model" right away, mixing the
X Window System calls to open and manage windows, cursors, and color
maps and read events of the window system, mouse and keyboard.
You can do that now with IRIS GL, if you are running IRIX 4.0.

In the X Window System, display mode choices (such as single or
double buffering, color index or RGBA mode) must be declared before
the window is initially opened.  You may also substitute for other
IRIS GL routines, such as using a OSF/Motif menu system, in place of
the IRIS GL pop-up menus.  You should use glXUseXFont(), whenever
you were using the font manager with IRIS GL.

Tables for states such as lighting or line and polygon stipples will
be gone.  Instead of using a def/set or def/bind sequence to load a
table, you turn on the state with glEnable() and also declare the
current values for that state.

Colors are best stored as floating point values, scaled from 0.0 to
1.0 (0% to 100%).  Alpha is fully integrated in the RGBA mode and
at least source alpha will be available on all OpenGL implementations.
OpenGL will not arbitrarily limit the number of bits per color to 8.
Clearing the contents of buffers no longer uses the current color, but
a special "clearing" color for each buffer (color, depth, stencil, and
accumulation).

The transformation matrix has changed.  In OpenGL, there is no
single matrix mode.  Matrices are now column-major and are post-multiplied,
although that does NOT change the calling order of these routines from
IRIS GL to OpenGL.  OpenGL's glRotate*() now allows for a rotation
around an arbitrary axis, not just the x, y, and z axes.  lookat()
of IRIS GL is now gluLookAt(), which takes an up vector value, not
merely a twist.  There is no polarview() in OpenGL, but a series
of glRotate*()s and glTranslate*()s can do the same thing.

There are no separate depth cueing routines in OpenGL.  Use linear fog.

Feedback and selection (picking) return values, which are different
from those found on any IRIS GL implementation.  For selection and
picking, depth values will be returned for each hit.  In OpenGL, feedback
and selection will now be standardized on all hardware platforms.

------
Subject:  Q13:  Who needs to license OpenGL?  Who doesn't?  How is a
commercial license acquired?

A:  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,
IBM, and Silicon Graphics who would distribute OpenGL with the
system software on their workstations or PCs.  Also, some
software vendors, such as Du Pont Pixel, MediaVision, and
Portable 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(TM) 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.

If you need a license or would like more information, call Mason
Woo at [phone] or e-mail him at [e-mail].  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.

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Subject:  Q14:  How does a university or research institution acquire access to
OpenGL source code?

A:  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 and can be
obtained by contacting [e-mail].

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Subject:  Q15:  Why doesn't SGI provide a free implementation of OpenGL?

A:  The intent of licensing is to enhance conformity and portability of
applications code.  In the days before OpenGL, IRIS GL was supported
differently and enhanced differently for each machine on which it was
implemented.  This included machines from IBM, HP, Sun, as well as SGI.
Applications developers found this to be a nightmare, and convinced
SGI that OpenGL implementations needed to be more consistent.  This
led us to develop specifications and conformance tests, and to seek
some way to ensure that OpenGL implementors would honor them.  There
are only a few legal mechanisms that can be used for this purpose,
and licensing is one of the most effective and widely accepted.  SGI
thinks the lack of a public-domain implementation is a trade-off for
a guarantee of consistent OpenGL implementations from many different
vendors, and that in the long run this is the best interests of
application developers, who seek ease of portability, and end-users,
who seek to be able to choose among hardware vendors for their chosen
software solution.

Licensing money goes to creating conformance tests to control variants
and subsets, maintaining the specification and sample implementation.
Because of the overhead of having the dozen or so engineers working
on OpenGL at SGI, SGI is not making money from the OpenGL effort.
Licensing is one way to help offset those costs.

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Subject:  Q16:  What are the conformance tests?

A:  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 trademark OpenGL.  Passing the conformance tests ensures
source code compatibility of applications across all OpenGL
implementations.

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Subject:  Q17:  How is the OpenGL governed?  Who decides what changes can be
made?

A:  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 DEC, IBM, Intel, Microsoft, and SGI.
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.

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Subject:  Q18:  Who are the current ARB members?

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

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Subject:  Q19:  What is the philosophy behind the structure of the ARB?

A:  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.

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Subject:  Q20:  How does the OpenGL ARB operate logistically?
When does the ARB have meetings?

A:  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 Advisory Forum/OpenGL ARB
meetings" or e-mail [e-mail] and ask for the
information.

Meetings are run by a set of by-laws, which are currently being
approved.  When they are approved, the by-laws will be publicly
available for inspection.

Minutes to the ARB meeting are posted to comp.graphics.opengl.

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Subject:  Q21:  How do additional members join the OpenGL ARB?

A:  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.

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Subject:  Q22:  So if I'm not a member of the ARB, am I shut out of
the decision making process?

A:  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.

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Subject:  Q23:  Are ARB meetings open to observers?

A:  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.

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Subject:  Q24:  What is the OpenGL Advisory Forum?

A:  The Advisory Forum is intended to start as an informal, self-governing
group of people, highly interested in OpenGL.  Corporations,
universities, or individuals can be members of the Advisory Forum.

OpenGL Advisory Forum meetings will be scheduled sporadically,
usually to coincide with trade shows or other popular gatherings
where people would be interested in programming with OpenGL.