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发信人: sunny (阳光), 信区: Graphics
标 题: Open GL FAQ 1
日 期: Tue Dec 26 09:58:33 1995
This FAQ is posted twice a month, on the 2nd, 16th of every month.
You may also want to see the OpenGL Web Page:
WWW URL http://www.sgi.com/Technology/openGL/
The FAQ has been split into 4 parts.
Part 1 is an index of questions.
Part 2 are general questions about OpenGL documentation, implementations,
licensing, and other general product information.
Part 3 is about OpenGL governance and the ARB.
Part 4 are technical questions, including where source code examples
can be found.
----- Part 2
Q_2_01: How do I submit changes or additions to this FAQ?
Q_2_02: What is OpenGL?
Q_2_03: Where are World Wide Web sites with information about OpenGL?
Q_2_04: What does the .gl or .GL file format have to do with OpenGL?
Q_2_05: What documentation is available for OpenGL? (A bibliography of
OpenGL documents is listed here.)
Q_2_06: Where can I get the OpenGL specification?
Q_2_07: Which vendors are licensing OpenGL?
Q_2_08: What OpenGL implementations are available?
Q_2_09: Does Windows 95 support OpenGL?
Q_2_10: What interest is there for OpenGL in Japan?
----- Part 3
Q_3_01: Who needs to license OpenGL? Who doesn't?
Q_3_02: What are the conformance tests?
Q_3_03: What is Silicon Graphics policy on "free"
implementations of APIs which resemble the OpenGL API?
Q_3_04: What is Mesa 3D and where can I get it?
Q_3_05: How does a university or research institution acquire access to
OpenGL source code?
Q_3_06: How is a commercial license acquired?
Q_3_07: How is the OpenGL governed? Who decides what changes can be made?
Q_3_08: Who are the current ARB members?
Q_3_09: What is the philosophy behind the structure of the ARB?
Q_3_10: How does the OpenGL ARB operate logistically? When does the
ARB have meetings?
Q_3_11: How do additional members join the OpenGL ARB?
Q_3_12: So if I'm not a member of the ARB, am I shut out of the decision
making process?
Q_3_13: Are ARB meetings open to observers?
Q_3_14: What benchmarks exist for OpenGL?
----- Part 4
Q_4_01: Where can I find OpenGL source code examples?
For instance, where is an example which combines OpenGL with Motif,
using the Motif widget?
Q_4_02: How do I contribute OpenGL code examples to a publicly accessible
archive?
Q_4_03: What is the GLUT toolkit? Where do I get it?
Q_4_04: What is the relationship between IRIS GL and OpenGL?
Is OpenGL source code or binary code compatible with IRIS GL?
Q_4_05: Why should I port my IRIS GL application to OpenGL?
Q_4_06: How much work is it to convert an IRIS GL program to OpenGL?
What are the major differences between them?
Q_4_07: When using Xlib, how do I create a borderless window?
Q_4_08: How do I switch between single buffer and double buffer mode?
Q_4_09: On my machine, it appears that glXChooseVisual is only able to
match double-buffered visuals. I want to have more bits of color
resolution, so how do I render in single buffer mode?
Q_4_10: I've got a 24-bit machine, but my OpenGL windows are not using
the full color resolution. What's wrong? My program looks fine
on one machine, but the depth buffer doesn't work on another.
What's wrong?
Q_4_11: What information is available about OpenGL extensions?
Q_4_12: How do I make shadows in OpenGL?
Q_4_13: How can I use 16 bit X fonts?
Q_4_14: What's in the new GLU 1.2 tesselator?
Q_4_15: Why is my glDrawPixels (or glCopyPixels or glReadPixels) slow?
Q_4_16: How can I used OpenGL with Tcl/Tk?
* marks recently modified answers or new questions
发信人: sunny (阳光), 信区: Graphics
标 题: OpenGL FAQ 2
日 期: Tue Dec 26 10:00:12 1995
------
Q_2_01: How do I submit changes or additions to this FAQ?
A: To request changes or additions, please send e-mail to
the FAQ maintainer. See the "Reply-To:" field in the header for
the e-mail address.
OpenGL licensees may want to contribute information to the
question: "What OpenGL implementations are available?" That
space is available for any company who wishes to state status
reports, release dates, contact names and phone numbers, or other
information for their OpenGL implementation.
It is asked that this information be relatively brief. Also, for
the sake of civility, each implementor is asked not to make
comparisons of their implementations against others.
Note that although a Silicon Graphics employee maintains this
FAQ, Silicon Graphics does not speak for any other company,
nor does it uphold the veracity of anyone else's information.
------
Q_2_02: What is OpenGL?
A: 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.
------
Q_2_03: Where are World Wide Web sites with information about 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/Technology/openGL/
Maintained by Thomas McReynolds <tomcat@sgi.com>.
IBM WWW Center for OpenGL
WWW URL http://www.austin.ibm.com/software/OpenGL
Template Graphics Software WWW Center for OpenGL
WWW URL http://www.sd.tgs.com/~template/Products/opengl.html
Microsoft Developer Network OffRamp Web Server
WWW URL http://www.microsoft.com
------
Q_2_04: What does the .gl or .GL file format have to do with OpenGL?
A: .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.
------
Q_2_05: What documentation is available for OpenGL?
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 Addison-Wesley (+1-617-944-3700).
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. "Graphics Users Debate Three Hot Topics," Open Systems Today,
December 12, 1994, p. HP3, HP8.
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.
Deffeyes, Suzy and John Spitzer. "OpenGL on OS/2," OS/2 Developer Magazine,
Nov/Dec 94, pages 34-45.
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.
Prosise, Jeff. "Advanced 3-D Graphics for Windows NT 3.5:
Introducing the OpenGL Interface, Part II," Microsoft Systems Journal,
November, 1994, Vol. 9, Number 11.
Prosise, Jeff. "Understanding Modelview Transformations in
OpenGL for Windows NT," Microsoft Systems Journal,
February, 1995, Vol. 10, Number 2.
Japanese language magazine articles and books
---------------------------------------------
"Interview with Masamichi Tachi about OpenGL_Japan,"
Nikkei Computer Graphics, 3/1995, p. 56-57.
Matsumoto, Masayuki, PIXEL, "OpenGL, A 3D Graphics Standard",
10/1994, p. 138-145.
Matsumoto, Masayuki, Toragi Computer,
"A introduction to OpenGL for PC users", 11/1994, p. 147-150.
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).
Nikkei Electronics, No. 616, Sept. 5, 1994, p. 99-105.
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).
"OpenGL," Nikkei Computer Graphics, 1/1995, p. 203-209.
PIXEL, No. 143, 8/94, p. 65 ("From the Editor's Desk"),
p. 117-121 ("3D API, OpenGL").
Sasaki, Akiko and Masayuki Matsumoto, Software Design, "Chapter 3: OpenGL",
November 11, 1994, ISSN 0916-6297, p. 26-48.
"Windows NT and OpenGL," Nikkei Computer Graphics, 3/1995, p. 156-161.
Woo, Mason, "OpenGL," Nikkei Computer Graphics, 11/1994,
p. 142.
"X Windows and OpenGL," Nikkei Computer Graphics, 2/1995, p. 155-160.
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.
------
Q_2_06: Where can I get the OpenGL specification?
A: 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/
------
Q_2_07: Which vendors are licensing OpenGL?
A: 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
------
Q_2_08: What OpenGL implementations are available?
A:
AccelGraphics
-------------
AccelGraphics, Inc. is currently shipping the AG300, a high-performance
PCI-based OpenGL(R) graphics board for the PC. AccelGraphics, Inc. is an
OpenGL licensee and provides full support of OpenGL via client-loadable
library on Windows NT(R) 3.5.
Running on a standard Pentium(TM), Alpha(TM), or MIPS(TM) PC with a PCI bus,
the AG300 graphics accelerator card lets you manipulate larger and more
complex 3D models and assemblies dynamically. True color and full 3D
acceleration, with a 16-bit Z-buffer and smooth double-buffered display at
full screen (1280x1024) resolution, combine to provide high-performance
dynamic viewing and rendering.
Hardware Support
Scalable architecture efficiently leverages the system CPU
7.5 MB of total RAM
5 MB of VRAM for 32 plane frame-buffer
2.5 MB of DRAM for 16-bit Z-buffer
Rectangle clipping, Alpha blending, Logic Operations, Bilinear
Interpolation, and Dithering
Supported Drivers and Applications
Microsoft Windows NT 3.5 or higher with OpenGL
Microsoft Windows 3.1
Windows 95(R) with OpenGL (late 1995)
Pro/ENGINEER(TM) and Pro/JR.(TM) from Parametric Technology Corporation
AutoCAD(TM) from Autodesk
MicroStation(TM) from Bentley Systems
Virtually any 3D application that utilizes OpenGL
Supported Hardware Platforms
Any Intel Pentium system with 1 free PCI slot
Digital's Alpha based PC's
MIPS based PC's
Supported Operating Systems
DOS, Windows 3.1, Windows NT
AccelGraphics, Inc. is headquartered in San Jose, CA
with regional offices in Atlanta, Orlando, Los Angeles,
Cincinnati and London, England.
For more information on the AG300, please call
AccelGraphics, Inc. at 1-800-444-5699.
AutoCAD is a registered trademark of Autodesk. Microstation
is a registered trademark of Bentley Systems. Pentium is a
trademark of Intel Corporation. AG300, ActionGraphics and
AccelGraphics are trademarks of AccelGraphics, Inc. Windows,
Windows NT and Windows 95 are registered trademarks of Microsoft
Corporation. OpenGL is a registered trademark of Silicon Graphics.
Pro/ENGINEER and Pro/JR. are trademarks of Parametric Technology
Corporation. All other trademarks are the property of the
companies that issued them.
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
At this time, Digital Equipment Corporation has no plans to offer
Open3D on either VAXstations or DECstations.
Digital Equipment Corporation (DEC) is shipping accelerated OpenGL for Windows
NT on our AlphaStation models 200 and 400 using the ZLXp-E1, ZLXp-E2, and
ZLXp-E3 graphics options.
Now you can unleash the industry-leading speed and power of Digital's Alpha
AXP technology with low-cost high-performance graphics accelerators that will
change the way you view your work.
The ZLXp-E1 provides leading 2D performance inexpensively. And breakthrough
dithering technology lets the ZLXp-E1 display 3D smooth shaded images in 8
planes with outstanding quality. Coupled with the ZLXp-E1's excellent
performance, Digital's patented dithering capability provides an ideal
solution for professionals in CASE, ECAD, and mechanical product design.
The ZLXp-E2 delivers the high-performance and 24 plane, true color capability
needed for image processing, medical imaging, desktop publishing, graphics
arts, and multimedia. The ZLXp-E2 can be configured to run 8 bits double
buffered with a 16 bit Z buffer, providing full dedicated hardware support for
3D applications.
The ZLXp-E3, featuring true color capability and a full 24 bit Z buffer for
even more complex solid model rendering, is ideal for mechanical CAD and
computer-aided molecular design.
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 (800) 763-0242 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 +1-402-691-0173
Portable Graphics, Inc.
-----------------------
3D Graphics Development and Porting Tools
Portable Graphics, a subsidiary of Evans & Sutherland Computer Corporation,
provides GL-based development and porting tools for a variety of workstation
platforms. Products for PCs (Windows NT, OS/2, Windows 95) will be
available in 1995.
OpenGL for Sun:
Portable Graphics' implementation of OpenGL for Sun is optimized for the
SPARC/Solaris environment and passes the ARB conformance tests, including
GLX server requirements for interoperability. Interoperability ensures
consistent client-server communications between any OpenGL implementation
across an X11 network. Native OpenGL on Freedom Series will be available
from Evans & Sutherland in 1st Quarter 1995. OpenGL can coexist with 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. Portable Graphics is an SMCC Catalyst Strategic Developer.
OpenGL for HP:
Hewlett-Packard has choosen Evans & Sutherland (E&S) as its OpenGL supplier.
OpenGL For Hewlett-Packard from E&S is now shipping for the HP Freedom
Series accelerators. For your convenience, development licenses can be
purchased directly from Hewlett-Packard or from Portable Graphics. Portable
Graphics offers volume and educational discounts. OpenGL for the entire HP
graphics accelerator product line is in development at E&S for release in
Summer 1995. Developers who wish to develop OpenGL and Open Inventor
applications for HP workstations with CRX or HCRX accelerators or the Model
712, can get started now using NPGL and IRIS Inventor. These applications
can then be converted to OpenGL and Open Inventor when these products
support the entire Series 700 product line.
Custom OpenGL Ports:
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, Sun
SPARCstation systems and HP Series 700 workstations with Freedom Series
graphics accelerators. Portable Graphics will also provide Open Inventor for
HP Series 700 workstations, Windows NT, Windows 95 and OS/2. 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 mid-1995 for Silicon Graphics
workstations, followed by support for Sun, IBM, and HP workstations, and
Windows NT, Windows 95 and OS/2.
Portable Graphics products are sold direct from the U.S. headquarters and
the U.K. office. Authorized distributors are located in Australia, France,
Germany, Japan and Taiwan.
For more information about OpenGL, Open Inventor, EDISON extensions to Open
Inventor, IRIS Inventor, or NPGL, contact:
Portable Graphics, Inc.
"An Evans & Sutherland Company"
One Technology Center
2201 Donley Drive, Suite 365
Austin, TX 78758
E-mail: glware@portable.com
Voice: (512) 719-8000
Fax: (512) 832-0752
Silicon Graphics
----------------
Starting with IRIX 5.2, OpenGL is supported for the following graphics
workstations:
Indy - Indy XL 8 or 24 bits, XZ (XZ, as of IRIX 5.3)
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
With IRIX 5.3, OpenGL is supported for these workstations:
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.)
* In final beta now, available via ftp
* 100% functional today
* Direct acceleration for Sun ZX, Turbo ZX
* Direct support for GX, TGX, SX board sets
* X11 network rendering to X terminals, PC-X servers, etc.
* PostScript hardcopy (on final release)
* GLX server extension for Solaris (on final)
* Does not require XGL for rendering
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 will also be providing OpenGL for Windows 3.1, direct to GDI, to ISV and
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 2.0 on UNIX and
PC systems, outside of SGI of course!
* Open Inventor for Solaris - shipping (beta)
* Open Inventor for IBM AIX - shipping (beta)
* Open Inventor for Windows NT 3.5 - in alpha
* Open Inventor for Windows 3.1 - 2Q95
* Open Inventor for Windows 95 - TBA
* Open Inventor for DEC OSF/1 - 2Q95
* Open Inventor for HP - 2Q95
* Open Inventor for Apple - 3Q95
* Open Inventor for OS/2 - TBA
Note: All of our Open Inventor products are tightly integrated
into the OpenGL on each system, including support for 3rd
party acceleration boards from Evans & Sutherland, GLINT,
and others. TGS is unique in our support for a direct
to hardware OpenGL for Solaris, Apple and is the only
vendor to support OpenGL for Win32s (Windows 3.1).
* TGS Power Tools (tm) for Open Inventor
TGS is also developing TGS Power Tools(tm) for Open Inventor which will
include:
* Power Filters (tm) - Import/Export of 3D metafiles
* Power Viewers (tm) - 3D Desktop Utilties
* Web3D (tm) - 3D Internet tools
Additional information on TGS Power Tools will be provided on request.
* 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. We also have distribution partners
in Europe and Asia.
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
info@tgs.com
Robert J. Weideman, V.P. Marketing
(619)457-5359 x229
(619)452-2547 (fax)
robert@tgs.com
3Dlabs
------
3Dlabs is currently shipping the GLINT 300SX, a high performance graphics
processor providing workstation class 3D graphics acceleration in a single
chip. Designed to accelerate OpenGL, the GLINT 300SX implements in hardware 3D
rendering operations such as Gouraud shading, depth buffering, anti-aliasing
and alpha blending.
Implemented around a scalable memory architecture, the GLINT 300SX reduces the
cost and complexity of delivering high performance 3D graphics - making it
ideal for a wide range of graphics products from PC boards to high-end
workstation accelerators. GLINT based products are already shipping from
several companies with other developments in progress.
Key features of the GLINT 300SX are:
- Full hardware support for Gourard shading, depth buffering, alpha
blending, anti-aliasing and dithering;
- 8, 16 or 32-bits per pixel RGBA and 4 or 8-bit color indexed;
- Screen resolutions up to 2560x2048;
- 16, 24 or 32-bit Z buffer;
- 4 or 8-bit stencil buffer
- Double buffering, stereo and overlay support ;
- PCI-bus Rev 2.0 interface with on-chip DMA;
- 112-bit memory interface.
Since hardware is worthless without software, 3Dlabs have developed a highly
optimized OpenGL driver for the GLINT 300SX. This OpenGL driver is currently
available under Windows NT 3.5 and will be ported to other operating systems
such as Windows 95. With GLINT 300SX and 3Dlabs' OpenGL GLINT driver,
applications have achieved up to a 3,000 percent 3D display performance
increase.
To find out more:
3Dlabs Inc
2010 North First Street, Suite 403
San Jose, CA 95131,
Tel: (408) 436 3455
Fax: (408) 436 3458
Email: info@3Dlabs.com
WWW URL http://www.3Dlabs.com/3Dlabs
------
Q_2_08: Does Windows 95 support OpenGL?
A: Steve Wright, the OpenGL Program Manager for Microsoft, says
``It will be available for Windows 95 through the Microsoft
Developers' Network later this year.''
------
Q_2_09: Does Windows 95 support OpenGL?
A: OpenGL_Japan user group:
http://www.sgi.com/Technology/openGL/opengl.japan.html
------
end of file
发信人: sunny (阳光), 信区: Graphics
标 题: OpenGL FAQ 3
日 期: Tue Dec 26 10:00:55 1995
------
Q_3_01: Who needs to license OpenGL? Who doesn't?
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,
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.
------
Q_3_02: 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 registered trademark OpenGL. Passing the
conformance tests ensures source code compatibility of
applications across all OpenGL implementations.
------
Q_3_03: 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.
------
Q_3_04: What is Mesa 3D and where can I get it?
From brianp@ssec.wisc.edu (Brian Paul)
The "Mesa 3-D graphics library" (or just Mesa) is a free
implementation of the OpenGL API. It has been compiled and
tested on most major Unix/X systems. All you should need is an
ANSI C compiler and X.
There is a WWW page at http://www.ssec.wisc.edu/~brianp/Mesa.html
You can get Mesa by anonymous ftp from iris.ssec.wisc.edu in the
pub/misc/ directory.
Mesa is currently in beta release. Some features are not yet
implemented and you may find new bugs. See the WWW page for
updated information.
Pedro Vazquez (vazquez@iqm.unicamp.br) has set up a mailing list
for users of the Mesa 3-D graphics library. Anyone who uses Mesa
and/or wants to be kept up to date on Mesa developments is
invited to subscribe.
To subscribe to the list send the following message to
listserv@iqm.unicamp.br
subs mesa <your name>
set mesa mail ack
For example:
subs mesa Brian Paul
set mesa mail ack
The second line tells the list processor to send you a copy of
your own messages.
You will receive a welcome message from the list server when you
have been added to the list. It tells you how to post messages
to the list, how to unsubscribe, etc.
------
Q_3_05: 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 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.
------
Q_3_06: 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.
------
Q_3_07: 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 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.
------
Q_3_08: Who are the current ARB members?
A: In alphabetical order: Digital Equipment, Evans & Sutherland,
IBM, Intel, Intergraph, Microsoft, and Silicon Graphics.
------
Q_3_09: 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.
------
Q_3_10: 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 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/
------
Q_3_11: 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.
------
Q_3_12: 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.
------
Q_3_13: 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.
------
Q_3_14: What benchmarks exist for OpenGL?
A:
OpenGL Performance Characterization for the GPC:
http://sunsite.unc.edu/gpc/opc.html
Viewperf 3.0 source:
ftp://net1.uspro.fairfax.va.us/pub/gpc/opc/viewperf/
------
end of file
发信人: sunny (阳光), 信区: Graphics
标 题: OpenGL FAQ 4
日 期: Tue Dec 26 10:01:49 1995
------
Q_4_01: Where can I find OpenGL source code examples? For instance,
where is an example which combines OpenGL with Motif, using
the Motif widget?
A: You can get the source code examples which are found in the
OpenGL Programming Guide via anonymous, public ftp from
ftp://sgigate.sgi.com/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
the GLUT toolkit (version 2.0) and OpenGL with Motif examples.
The directory is ftp://sgigate.sgi.com/pub/opengl/xjournal
Some contributed source code of useful tools for developing
OpenGL code can be found on ftp://sgigate.sgi.com/pub/opengl/contrib
Source code found here includes:
isfast--compares the performance of OpenGL states
samples--more OpenGL program examples
toogl--helps port IRIS GL code to OpenGL
xglinfo--display information on X visuals extended for OpenGL
xscope--examines OpenGL protocol sent to an extended X server
------
Q_4_02: How do I contribute OpenGL code examples to a publicly
accessible archive?
A: To contribute to the public OpenGL archive, send mail to
opengl-contrib@sgi.com. 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 ftpmail@decwrl.dec.com with a message body containing only the word
"help".
------
Q_4_03: What is the GLUT toolkit? Where do I get it?
A: GLUT is a portable toolkit which performs window and event
operations to support OpenGL rendering.
GLUT version 2.0 has:
o window functions, including multiple windows for OpenGL rendering
o callback driven event processing
o sophisticated input devices, including dials and buttons box,
tablet, Spaceball(TM)
o idle routines and timers
o a simple cascading pop-up menu facility
o routines to generate wire and solid objects
o bitmap and stroke fonts
o request and queries for multisample and stereo windows
o OpenGL extension query support
The version 2 functionality is fully backward compatible
with the version 1 functionality.
The specification, source code (including FORTRAN bindings),
and articles for GLUT (Graphics Library Utility Toolkit) is in:
URL ftp://sgigate.sgi.com/pub/opengl/xjournal/GLUT
This distribution of GLUT should compile on:
o DEC Alpha workstation running OSF/1 with Open3D layered product
o IBM RS/6000 workstations running AIX with OpenGL support
o SGI workstation running IRIX 5.2 or higher supporting OpenGL
o Template Graphics Software's OpenGL for Sun workstations
o Mesa 1.1 for Unix workstations.
------
Q_4_04: What is the relationship between IRIS GL and OpenGL?
Is OpenGL source code or binary code compatible with IRIS GL?
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.
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.
------
Q_4_05: Why should I port my IRIS GL application to OpenGL?
A: 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.
------
Q_4_06: How much work is it to convert an IRIS GL program to OpenGL?
What are the major differences between them?
A: from Mason Woo (woo@sgi.com) and Debbie Herrington (debbie@portable.com)
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.
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.
OpenGL uses standard, predictable naming conventions, which required
that all names have been changed from IRIS GL. The OpenGL
naming scheme uses unique prefixes, suffixes, and capitalization to
help prevent potential conflicts among application, system, and
library routine names.
And all routine names have changed,
at least, minimally; for example: ortho() is now glOrtho().
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.
------
Q_4_07: When using Xlib, how do I create a borderless window?
A:
from blythe@sgi.com (David Blythe)
Essentially you can create the window with override-redirect
(see man xcreatewindow) which is the sledgehammer approach or
you can change the _MOTIF_WM_HINTS property to tell the window
manager to leave your windows undecorated.
from alex@eagle.hd.hac.com (Alex Madarasz)
Also of note is that the window manager decorations of any client can be
turned off by putting something like the following in the .Xdefaults
file in your home directory - assuming you aren't overriding them in
your app:
4Dwm*ClientAppOrClassName*clientDecoration: none
( see the 4Dwm / mwm man pages for a full description of this resource )
( you must restart the window manager or logout/login for 4Dwm resources
to take effect )
"none" will remove all of the window manager decorations - border, title
bar etc.
------
Q_4_08: How do I switch between single buffer and double buffer mode?
A: from mjk@sgi.com (Mark Kilgard) and blythe@sgi.com (David Blythe)
When using OpenGL with X, switching between a double buffered and
single buffered window can be accomplished by creating a "container"
X window and creating two subwindows, one with a double buffer visual,
the other with a single buffer visual. Make sure the subwindows are each
the full size of their parent window.
You can then use XRaiseWindow or XLowerWindow to change the stacking
order of the two subwindows to switch between double buffering and
single buffering.
You will need to create a separate context for each of the
two windows since they have different visual types. You will need
to make the appropriate window/context pair current when you switch
modes.
IRIS GL made it easy to switch between double buffering and single
buffering. But essentially, IRIS GL implemented the above process
internally.
------
Q_4_09: On my machine, it appears that glXChooseVisual is only able
to match double-buffered visuals. I want to have more bits
of color resolution, so how do I render in single buffer mode?
A: from mjk@sgi.com (Mark Kilgard)
On mid- to low-end machines with double buffer hardware, you'll
probably find you get twice as much color resolution using a single
buffer visual. But if there is no hardware double buffering support,
the double buffered and single buffered visuals are generally the
same depth (the back buffer is "carved" out of software).
Search again for a double buffered visual. If you find one,
use it instead. Call glDrawBuffer(GL_FRONT) though to make sure
you are drawing to the front buffer (the default for a double
buffered visual is to draw into the back buffer).
------
Q_4_10: I've got a 24-bit machine, but my OpenGL windows are not using
the full color resolution. What's wrong? My program looks
fine on one machine, but the depth buffer doesn't work on
another. What's wrong?
A: from mjk@sgi.com (Mark Kilgard) and woo@sgi.com (Mason Woo)
An unfortunate (but documented) semantic of glXChooseVisual is
that if you don't request GLX_RED_SIZE, GLX_GREEN_SIZE, or
GLX_BLUE_SIZE, glXChooseVisual assumes zero for these parameters
which means pick the visual with the _smallest_ amount of red,
green, and blue that matches the other visual attributes. Make
sure you ask for at least 1 bit of GLX_RED_SIZE, GLX_GREEN_SIZE,
and GLX_BLUE_SIZE. If these configuration parameters are
non-zero, it matches the visual with the _largest_ amount of red,
green, and blue with at least 1 bit of each (probably what you
want).
Similarly, if you don't request GLX_DEPTH_SIZE, you may get a
visual with zero bits of depth buffer. Some systems may have few
visuals available, and those visuals all have at least 1 bit of
depth buffer. On other systems, there may be dozens of visuals
available, some with zero bits for the depth buffer. In short,
if hidden surface removal appears to fail, check to see if you
have explicitly specified any bits of depth buffer you have requested.
Also check to see what visual you have received.
------
Q_4_11: What information is available about OpenGL extensions?
A: Examples of extensions include vertex arrays (calling several vertexes
or related data, such as normals or colors, with a single function call),
blending of constant colors, polygon offset (multiple coplanar polygons
can be rendered without interaction),
Procedure names and tokens for OpenGL extensions are either suffixed
with EXT or a vendor-specific acronym: such as SGI for Silicon Graphics
machines, or INGR for Intergraph. Also note that Silicon Graphics
extensions to OpenGL are suffixed to indicate whether they will be
available on all machines (SGI), on just a subset of machines (SGIS),
or are very experimental and may become unavailable or completely
changed (SGIX).
Vendors are encouraged to add extension information to their
documentation. For Silicon Graphics, extension information is
summarized on the glIntro man page.
------
Q_4_12: How do I make shadows in OpenGL?
A: There are no individual routines to control shadows nor
an OpenGL state for shadows. However, code can be written
to render shadows.
from woo@sgi.com (Mason Woo)
To project a shadow onto a flat plane (such as in the insect
demo), draw the stippled object, flattened using matrix transformations.
The easiest way to flatten an object is to use the scale function.
For example, use glScalef(1., 0., 1.) to create from an infinite light
shining straight down the y axis. A transformation matrix
can be used to cast a shadow from an infinite or local light source
in an arbitrary direction. See the article:
Thant Tessman, "Casting Shadows on Flat Surfaces,"
IRIS Universe, Winter, 1989.
from shreiner@sgi.com (Dave Shreiner)
Check out the fast shadow and projective texture multi-pass
algorithms for producing realistic shadows using texture mapping.
See the SIGGRAPH paper:
Mark Segal, Carl Korobkin, et al.
"Fast Shadows and Lighting Effects using Texture Mapping"
1992 SIGGRAPH Proceedings
------
Q_4_13: How can I use 16 bit X fonts?
A: from James A. ("Jim") Miller
Here is some code that will load any font into the server and use glXUseXFont
to build the display lists for you (this does work with 16 bit fonts, it has
been tested on IBM, DEC and SGI machines at an OpenGL interop testing).
Once your display lists are created for each character, you can use the same
basic logic to figure out which characters are valid (using first, last,
firstrow and lastrow in the sample code to get :
firstchar = 256 * firstrow + first
lastchar = 256 * lastrow + last ) and use glCallList with those characters
to print them out.
static int LoadFont(char *fontName)
{
Font id;
int first, last, firstbitmap, i;
GLuint base;
Display *display=0;
int firstrow, lastrow;
int maxchars;
tkGetSystem(TK_X_DISPLAY, &display);
fontInfo = XLoadQueryFont(display, fontName);
if (fontInfo == NULL) {
return 0;
}
id = fontInfo->fid;
/*
* First and Last char in a row of chars
*/
first = (int)fontInfo->min_char_or_byte2;
last = (int)fontInfo->max_char_or_byte2;
/*
* First and Last row of chars, important for multibyte charset's
*/
firstrow = (int)fontInfo->min_byte1;
lastrow = (int)fontInfo->max_byte1;
/*
* How many chars in the charset
*/
maxchars = 256 * lastrow + last;
base = glGenLists(maxchars+1);
if (base == 0) {
return 0;
}
/*
* Get offset to first char in the charset
*/
firstbitmap = 256 * firstrow + first;
/*
* for each row of chars, call glXUseXFont to build the bitmaps.
*/
for(i=firstrow; i<=lastrow; i++)
{
glXUseXFont(id, firstbitmap, last-first+1, base+firstbitmap);
firstbitmap += 256;
}
return base;
}
------
Q_4_14: What's in the new GLU 1.2 tesselator?
A: from Mark Kilgard
Our friends at Digital have the answers:
http://www.digital.com:80/pub/doc/opengl/opengl_new_glu.html
------
Q_4_15: Why is my glDrawPixels (or glCopyPixels or glReadPixels) slow?
A: from Allen Akin
It's not, for the most common cases. After all, similar microcode
and the same hardware are used for both commands. However, there
are three issues to keep in mind.
First, some midrange and low-end SGI graphics adaptors (particularly
XS, XZ, Elan, and Extreme) transfer ABGR-ordered images much faster
than they transfer RGBA-ordered images. The normal image format in
IrisGL was ABGR, while in OpenGL it's RGBA. So to achieve the same
performance in OpenGL that you did in IrisGL on those machines, you
need to use ABGR-format images in OpenGL. The ABGR extension
available in Irix 5.3 and later releases allows you to do this. See
``man glintro'' for background information on using OpenGL extensions,
and ``man gldrawpixels'' for details on ABGR. Note that
RealityEngine, IMPACT, and all future machines will process RGBA data
at least as fast as ABGR, so RGBA is the way to go for new code.
Second, some OpenGL pixel data types are faster than others. For most
machines, unsigned byte RGBA (or ABGR) is the fastest full-color type.
Unsigned byte and unsigned short are usually the fastest gray-scale
types. Signed integer types are slower.
Third, OpenGL pixel operations have a much richer set of features than
IrisGL, and if any of those features are enabled, then image transfer
can be significantly slower. Always disable the features that you
don't need. The following code fragment disables features that are
likely to make glDrawPixels slow:
/*
* Disable stuff that's likely to slow down glDrawPixels.
* (Omit as much of this as possible, when you know in advance
* that the OpenGL state will already be set correctly.)
* Note that all of these are the default settings, except
* for GL_DITHER!
*/
glDisable(GL_ALPHA_TEST);
glDisable(GL_BLEND);
glDisable(GL_DEPTH_TEST);
glDisable(GL_DITHER);
glDisable(GL_FOG);
glDisable(GL_LIGHTING);
glDisable(GL_LOGIC_OP);
glDisable(GL_STENCIL_TEST);
glDisable(GL_TEXTURE_1D);
glDisable(GL_TEXTURE_2D);
glPixelTransferi(GL_MAP_COLOR, GL_FALSE);
glPixelTransferi(GL_RED_SCALE, 1);
glPixelTransferi(GL_RED_BIAS, 0);
glPixelTransferi(GL_GREEN_SCALE, 1);
glPixelTransferi(GL_GREEN_BIAS, 0);
glPixelTransferi(GL_BLUE_SCALE, 1);
glPixelTransferi(GL_BLUE_BIAS, 0);
glPixelTransferi(GL_ALPHA_SCALE, 1);
glPixelTransferi(GL_ALPHA_BIAS, 0);
/*
* Disable extensions that could slow down glDrawPixels.
* (Actually, you should check for the presence of the proper
* extension before making these calls. I've omitted that
* code for simplicity.)
*/
#ifdef GL_EXT_convolution
glDisable(GL_CONVOLUTION_1D_EXT);
glDisable(GL_CONVOLUTION_2D_EXT);
glDisable(GL_SEPARABLE_2D_EXT);
#endif
#ifdef GL_EXT_histogram
glDisable(GL_HISTOGRAM_EXT);
glDisable(GL_MINMAX_EXT);
#endif
#ifdef GL_EXT_texture3D
glDisable(GL_TEXTURE_3D_EXT);
#endif
------
Q_4_16: How can I used OpenGL with Tcl/Tk?
A: TIGER 1.2: ftp://metallica.prakinf.tu-ilmenau.de/pub/PROJECTS/TIGER1.2/
Tix: http://www.cis.upenn.edu/~ioi/tix/sgi.html
------
end of file
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