1. Introduction

This is the Linux 3Dfx HOWTO document. It is intended as a quick
reference covering everything you need to know to install and
configure 3Dfx support under Linux. Frequently asked questions
regarding the 3Dfx support are answered, and references are given to
some other sources of information on a variety of topics related to
computer generated, hardware accelerated 3D graphics.

This information is only valid for Linux on the Intel platform. Some
information may be applicable to other processor architectures, but I
have no first hand experience or information on this. It is only
applicable to boards based on 3Dfx technology, any other graphics
accelerator hardware is beyond the scope of this document.



1.1. Contributors and Contacts

This document would not have been possible without all the information
contributed by other people - those involved in the Linux Glide port
and the beta testing process, in the development of Mesa and the Mesa
Voodoo drivers, or rewieving the document on behalf of 3Dfx and
Quantum3D. Some of them contributed entire sections to this document.

Daryll Strauss daryll@harlot.rb.ca.us did the port, Paul J. Metzger
pjm@rbd.com modified the Mesa Voodoo driver (written by David
Bucciarelli tech.hmw@plus.it) for Linux, Brian Paul brianp@RA.AVID.COM
integrated it with his famous Mesa library. With respect to Voodoo
Graphics (tm) accelerated Mesa, additional thanks has to go to Henri
Fousse, Gary McTaggart, and the maintainer of the 3Dfx Mesa for DOS,
Charlie Wallace Charlie.Wallace@unistudios.com. The folks at 3Dfx,
notably Gary Sanders, Rod Hughes, and Marty Franz, provided valuable
input, as did Ross Q. Smith of Quantum3D. The pages on the Voodoo
Extreme and Operation 3Dfx websites provided useful info as well, and
in some case I relied on the 3Dfx local Newsgroups. The Linux glQuake2
port that uses Linux Glide and Mesa is maintained by Dave Kirsch
zoid@idsoftware.com. Thanks to all those who sent e-mail regarding
corrections and updates, and special thanks to Mark Atkinson for
reminding me of the dual cable setup.

Thanks to the SGML-Tools package (formerly known as Linuxdoc-SGML),
this HOWTO is available in several formats, all generated from a
common source file. For information on SGML-Tools see its homepage at
pobox.com/~cg/sgmltools.



1.2. Acknowledgments

3Dfx, the 3Dfx Interactive logo, Voodoo Graphics (tm), and Voodoo Rush
(tm) are registered trademarks of 3Dfx Interactive, Inc. Glide,
TexUS, Pixelfx and Texelfx are trademarks of 3Dfx Interactive, Inc.
OpenGL is a registered trademark of Silicon Graphics. Obsidian is a
trademark of Quantum3D. Other product names are trademarks of the
respective holders, and are hereby considered properly acknowledged.


1.3. Revision History


Version 1.03
First version for public release.

Version 1.16
Current version v1.16 6 February 1998.



1.4. New versions of this document

You will find the most recent version of this document at
www.gamers.org/dEngine/xf3D/.

New versions of this document will be periodically posted to the
comp.os.linux.answers newsgroup. They will also be uploaded to various
anonymous ftp sites that archive such information including
ftp://sunsite.unc.edu/pub/Linux/docs/HOWTO/.

Hypertext versions of this and other Linux HOWTOs are available on
many World-Wide-Web sites, including sunsite.unc.edu/LDP/. Most Linux
CD-ROM distributions include the HOWTOs, often under the
/usr/doc/directory, and you can also buy printed copies from several
vendors.

If you make a translation of this document into another language, let
me know and I'll include a reference to it here.



1.5. Feedback

I rely on you, the reader, to make this HOWTO useful. If you have any
suggestions, corrections, or comments, please send them to me (
bk@gamers.org), and I will try to incorporate them in the next
revision. Please add HOWTO 3Dfx to the Subject-line of the mail, so
procmail will dump it in the appropriate folder.

Before sending bug reports or questions, please read all of the
information in this HOWTO, and send detailed information about the
problem.

If you publish this document on a CD-ROM or in hardcopy form, a
complimentary copy would be appreciated. Mail me for my postal
address. Also consider making a donation to the Linux Documentation
Project to help support free documentation for Linux. Contact the
Linux HOWTO coordinator, Tim Bynum (linux-howto@sunsite.unc.edu), for
more information.



1.6. Distribution Policy

Copyright (c) 1997, 1998 by Bernd Kreimeier. This document may be
distributed under the terms set forth in the LDP license at
sunsite.unc.edu/LDP/COPYRIGHT.html.

This HOWTO is free documentation; you can redistribute it and/or
modify it under the terms of the LDP license. This document is
distributed in the hope that it will be useful, but without any
warranty; without even the implied warranty of merchantability or
fitness for a particular purpose. See the LDP license for more
details.



2. Graphics Accelerator Technology

2.1. Basics

This section gives a very cursory overview of computer graphics
accelerator technology, in order to help you understand the concepts
used later in the document. You should consult e.g. a book on OpenGL
in order to learn more.


2.2. Hardware configuration

Graphics accelerators come in different flavors: either as a separate
PCI board that is able to pass through the video signal of a (possibly
2D or video accelerated) VGA board, or as a PCI board that does both
VGA and 3D graphics (effectively replacing older VGA controllers).
The 3Dfx boards based on the Voodoo Graphics (tm) belong to the former
category. We will get into this again later.


If there is no address conflict, any 3D accelerator board could be
present under Linux without interfering, but in order to access the
accelerator, you will need a driver. A combined 2D/3D accelerator
might behave differently.


2.3. A bit of Voodoo Graphics (tm) architecture

Usually, accessing texture memory and frame/depth buffer is a major
bottleneck. For each pixel on the screen, there are at least one
(nearest), four (bi-linear), or eight (tri-linear mipmapped) read
accesses to texture memory, plus a read/write to the depth buffer, and
a read/write to frame buffer memory.

The Voodoo Graphics (tm) architecture separates texture memory from
frame/depth buffer memory by introducing two separate rendering
stages, with two corresponding units (Pixelfx and Texelfx), each
having a separate memory interface to dedicated memory. This gives an
above-average fill rate, paid for restrictions in memory management
(e.g. unused framebuffer memory can not be used for texture caching).

Moreover, a Voodoo Graphics (tm) could use two TMU's (texture
management or texelfx units), and finally, two Voodoo Graphics (tm)
could be combined with a mechanism called Scan-Line Interleaving
(SLI). SLI essentially means that each Pixelfx unit effectively
provides only every other scanline, which decreases bandwidth impact
on each Pixelfx' framebuffer memory.



3. Installation

Configuring Linux to support 3Dfx accelerators involves the following
steps:

1. Installing the board.

2. Installing the Glide distribution.

3. Compiling, linking and/or running the application.

The next sections will cover each of these steps in detail.


3.1. Installing the board

Follow the manufacturer's instructions for installing the hardware or
have your dealer perform the installation. It should not be necessary
to select settings for IRQ, DMA channel, either Plug&Pray (tm) or
factory defaults should work. The add-on boards described here are
memory mapped devices and do not use IRQ's. The only kind of conflict
to avoid is memory overlap with other devices.

As 3Dfx does not develop or sell any boards, do not contact them on
any problems.


3.1.1. Troubleshooting the hardware installation

To check the installation and the memory mapping, do cat /proc/pci.
The output should contain something like

______________________________________________________________________
Bus 0, device 12, function 0:
VGA compatible controller: S3 Inc. Vision 968 (rev 0).
Medium devsel. IRQ 11.
Non-prefetchable 32 bit memory at 0xf4000000.

Bus 0, device 9, function 0:
Multimedia video controller: Unknown vendor Unknown device (rev 2).
Vendor id=121a. Device id=1.
Fast devsel. Fast back-to-back capable.
Prefetchable 32 bit memory at 0xfb000000.
______________________________________________________________________


for a Diamond Monster 3D used with a Diamond Stealth-64. Additionally
a cat /proc/cpuinfo /proc/meminfo might be helpfull for tracking down
conflicts and/or submitting a bug report.

With current kernels, you will probably get a boot warning like

______________________________________________________________________
Jun 12 12:31:52 hal kernel: Warning : Unknown PCI device (121a:1).
Please read include/linux/pci.h
______________________________________________________________________


which could be safely ignored. If you happen to have a board not very
common, or have encountered a new revision, you should take the time
to follow the advice in /usr/include/linux/pci.h and send all neces-
sary information to linux-pcisupport@cao-vlsi.ibp.fr.

If you experience any problems with the board, you should try to
verify that DOS and/or Win95 or NT support works. You will probably
not receive any useful response from a board manufacturer on a bug
report or request regarding Linux. Having dealt with the Diamond
support e-mail system, I would not expect useful responses for other
operating systems either.


3.1.2. Configuring the kernel

There is no kernel configuration necessary, as long as PCI support is
enabled. The Linux Kernel HOWTO
should be
consulted for the details of building a kernel.



3.1.3. Configuring devices

The current drivers do not (yet) require any special devices. This is
different from other driver developments (e.g. the sound drivers,
where you will find a /dev/dsp and /dev/audio). The driver uses the
/dev/mem device which should always be available. In consequence, you
need to use setuid or root privileges to access the accelerator board.


3.2. Setting up the Displays

There are two possible setups with add-on boards. You could either
pass-through the video signal from your regular VGA board via the
accelerator board to the display, or you could use two displays at the
same time. Rely to the manual provided by the board manufacturer for
details. Both configurations have been tried with the Monster 3D
board.


3.2.1. Single screen display solution

This configuration allows you to check basic operations of the
accelerator board - if the video signal is not transmitted to the
display, hardware failure is possible.

Beware that the video output signal might deteoriate significantly if
passed through the video board. To a degree, this is inevitable.
However, reviews have complained about below-average of the cables
provided e.g. with the Monster 3D, and judging from the one I tested,
this has not changed.

There are other pitfalls in single screen configurations. Switching
from the VGA display mode to the accelerated display mode will change
resolution and refresh rate as well, even if you are using 640x480
e.g. with X11, too. Moreover, if you are running X11, your
application is responsible for demanding all keyboard and mouse
events, or you might get stuck because of changed scope and exposure
on the X11 display (that is effectively invisible when the accelerated
mode is used) You could use SVGA console mode instead of X11.

If you are going to use a single screen configuration and switch modes
often, remember that your monitor hardware might not enjoy this kind
of use.



3.2.2. Single screen dual cable setup

Some high end monitors (e.g. the EIZO F-784-T) come with two
connectors, one with 5 BNC connectors for RGB, HSync, VSync, the other
e.g. a regular VGA or a 13W3 Sub-D VGA. These displays usually also
feature a front panel input selector to safely switch from one to the
other. It is thus possible to use e.g. a VGA-to-BNC cable with your
high end 2D card, and a VGA-to-13W3 Sub-D cable with your 3Dfx, and
effectively run dual screen on one display.


3.2.3. Dual screen display solution

The accelerator board does not need the VGA input signal. Instead of
routing the common video output through the accelerator board, you
could attach a second monitor to its output, and use both at the same
time. This solution is more expensive, but gives best results, as your
main display will still be hires and without the signal quality losses
involved in a pass-through solution. In addition, you could use X11
and the accelerated full screen display in parallel, for development
and debugging.

A common problem is that the accelerator board will not provide any
video signal when not used. In consequence, each time the graphics
application terminates, the hardware screensave/powersave might kick
in depending on your monitors configuration. Again, your hardware
might not enjoy being treated like this. You should use

______________________________________________________________________
setenv SST_DUALSCREEN 1
______________________________________________________________________


to force continued video output in this setup.


3.3. Installing the Glide distribution

The Glide driver and library are provided as a single compressed
archive. Use tar and gzip to unpack, and follow the instructions in
the README and INSTALL accompanying the distribution. Read the
install script and run it. Installation puts everything in
/usr/local/glide/include,lib,bin and sets the ld.conf to look there.
Where it installs and setting ld.conf are independent actions. If you
skip the ld.conf step then you need the LD_LIBRARY_PATH.

You will need to install the header files in a location available at
compile time, if you want to compile your own graphics applications.
If you do not want to use the installation as above (i.e. you insist
on a different location), make sure that any application could access
the shared libary at runtime, or you will get a response like can't
load library 'libglide.so'.



3.3.1. Using the detect program

There is a bin/detect program in the distribution (the source is not
available). You have to run it as root, and you will get something
like

______________________________________________________________________
slot vendorId devId baseAddr0 command description
---- -------- ------ ---------- ------- -----------
00 0x8086 0x122d 0x00000000 0x0006 Intel:430FX (Triton)
07 0x8086 0x122e 0x00000000 0x0007 Intel:ISA bridge
09 0x121a 0x0001 0xfb000008 0x0002 3Dfx:video multimedia adapter
10 0x1000 0x0001 0x0000e401 0x0007 ???:SCSI bus controller
11 0x9004 0x8178 0x0000e001 0x0017 Adaptec:SCSI bus controller
12 0x5333 0x88f0 0xf4000000 0x0083 S3:VGA-compatible display co
______________________________________________________________________


as a result. If you do not have root privileges, the program will bail
out with

______________________________________________________________________
Permission denied: Failed to change I/O privilege. Are you root?
______________________________________________________________________


output might come handy for a bug report as well.



3.3.2. Using the test programs

Within the Glide distribution, you will find a folder with test
programs. Note that these test programs are under 3Dfx copyright, and
are legally available for use only if you have purchased a board with
a 3Dfx chipset. See the LICENSE file in the distribution, or their web
site www.3dfx.com for details.

It is recommend to compile and link the test programs even if there
happen to be binaries in the distribution. Note that some of the
programs will requires some files like alpha.3df from the distribution
to be available in the same folder. All test programs use the 640x480
screen resolution. Some will request a veriety of single character
inputs, others will just state Press A Key To Begin Test. Beware of
loss of input scope if running X11 on the same screen at the same
time.

See the README.test for a list of programs, and other details.



4. Answers To Frequently Asked Questions

The following section answers some of the questions that (will) have
been asked on the Usenet news groups and mailing lists. The FAQ has
been subdivided into several parts for convenience, namely

o FAQ: Requirements?

o FAQ: Voodoo Graphics (tm)? 3Dfx?

o FAQ: Glide?

o FAQ: Glide and SVGA?

o FAQ: Glide and XFree86?

o FAQ: Glide versus OpenGL/Mesa?

o FAQ: But Quake?

o FAQ: Troubleshooting?

Each section lists several questions and answers, which will
hopefully address most problems.



5. FAQ: Requirements?



5.1. What are the system requirements?

A Linux PC, PCI 2.1 compliant, a monitor capable of 640x480, and a 3D
accelerator board based on the 3Dfx Voodoo Graphics (tm). It will work
on a P5 or P6, with or without MMX. The current version does not use
MMX, but it has some optimized code paths for P6.

At one point, some 3Dfx statements seemed to imply that using Linux
Glide required using a RedHat distribution. Note that while Linux
Glide has originally been ported in a RedHat 4.1 environment, it has
been used and tested with many other Linux distributions, including
homebrew, Slackware, and Debian 1.3.1.


5.2. Does it work with Linux-Alpha?

There is currently no Linux Glide distribution available for any
platform besides i586. As the Glide sources are not available for
distribution, you will have to wait for the binary. Quantum3D has DEC
Alpha support announced for 2H97. Please contact Daryll Strauss if you
are interested in supporting this.

There is also the issue of porting the the assembly modules. While
there are alternative C paths in the code, the assembly module in
Glide (essentially triangle setup) offered significant performance
gains depending on the P5 CPU used.



5.3. Which 3Dfx chipsets are supported?

Currently, the 3Dfx Voodoo Graphics (tm) chipset is supported under
Linux. The Voodoo Rush (tm) chipset is not yet supported.


5.4. Is the Voodoo Rush (tm) supported?

The current port of Glide to Linux does not support the Voodoo Rush
(tm). An update is in the works.

The problem is that at one point the Voodoo Rush (tm) driver code in
Glide depended on Direct Draw. There was an SST96 based DOS portion in
the library that could theoretically be used for Linux, as soon as all
portions residing in the 2D/Direct Draw/D3D combo driver are replaced.

Thus Voodoo Rush (tm) based boards like the Hercules Stingray 128/3D
or Intergraph Intense Rush are not supported yet.



5.5. Which boards are supported?

There are no officially supported boards, as 3Dfx does not sell any
boards. This section does not attempt to list all boards, it will just
give an overview, and will list only boards that have been found to
cause trouble.

It is important to recognize that Linux support for a given board does
not only require a driver for the 3D accelerator component. If a board
features its own VGA core as well, support by either Linux SVGA or
XFree86 is required as well (see section about Voodoo Rush (tm)
chipset). Currently, an add-on solution is recommended, as it allows
you to choose a regular graphics board well supported for Linux. There
are other aspects discussed below.


All Quantum3D Obsidian boards, independend of texture memory, frame
buffer memory, number of Pixelfx and Texelfx units, and SLI should
work. Same for all other Voodoo Graphics (tm) based boards, like
Orchid Righteous 3D, Canopus Pure 3D, Flash 3D, and Diamond Monster
3D. Voodoo Rush (tm) based boards are not yet supported.

Boards that are not based on 3Dfx chipsets (e.g. manufactured by S3,
Matrox, 3Dlabs, Videologic) do not work with the 3Dfx drivers and are
beyond the scope of this document.



5.6. How do boards differ?

As the board manufacturers are using the same chipset, any differences
are due to board design. Examples are quality of the pass-through
cable and connectors (reportedly, Orchid provided better quality than
Diamond), availability of a TV-compliant video signal output (Canopus
Pure 3D), and, most notably, memory size on board.

Most common were boards for games with 2MB texture cache and 2 MB
framebuffer memory, however, the Canopus Pure3D comes with a maximal 4
MB texture cache, which is an advantage e.g. with games using
dynamically changed textures, and/or illumation textures (Quake, most
notably). The memory architecture of a typical Voodoo Graphics (tm)
board is described below, in a separate section.

Quantum 3D offers the widest selection of 3Dfx-based boards, and is
probably the place to go if you are looking for a high end Voodoo
Graphics (tm) based board configuration. Quantum 3D is addressing the
visual simulation market, while most of the other vendors are only
targetting the consumer-level PC-game market.



5.7. What about AGP?

There is no Voodoo Graphics (tm) or Voodoo Rush (tm) AGP board that I
am aware of. I am not aware of AGP support under Linux, and I do not
know whether upcmong AGP boards using 3Dfx technology might possibly
be supported with Linux.



6. FAQ: Voodoo Graphics (tm)? 3Dfx?

6.1. Who is 3Dfx?

3Dfx is a San Jose based manufacturer of 3D graphics accelerator
hardware for arcade games, game consoles, and PC boards. Their
official website is www.3dfx.com. 3Dfx does not sell any boards, but
other companies do, e.g. Quantum3D.



6.2. Who is Quantum3D?

Quantum3D started as a 3Dfx spin-off, manufacturing high end
accelerator boards based on 3Dfx chip technology for consumer and
business market, and supplying arcade game technology. See their home
page at www.quantum3d.com for additional information. For general
inquiries regarding Quantum3D, please send mail to info@quantum3d.


6.3. What is the Voodoo Graphics (tm)?

The Voodoo Graphics (tm) is a chipset manufactured by 3Dfx. It is used
in hardware acceleration boards for the PC. See the HOWTO section on
supported hardware.


6.4. What is the Voodoo Rush (tm)?

The Voodoo Rush (tm) is a derivate of the Voodoo Graphics (tm) that
has an interface to cooperate with a 2D VGA video accelerator,
effectively supporting accelerated graphics in windows. This combo is
currently not supported with Linux.


6.5. What is the Voodoo 2 (tm)?

The Voodoo 2 (tm) is the successor of the Voodoo Graphics (tm)
chipset, featuring several improvements. It is announced for late
March 1998, and annoucements of Voodoo 2 (tm) based boards have been
published e.g. by Quantum 3D, by Creative Labs, Orchid Technologies,
and Diamond Multimedia.

The Voodoo 2 (tm) is supposed to be backwards compatible. However, a
new version of Glide will have to be ported to Linux.



6.6. What is VGA pass-though?

The Voodoo Graphics (tm) (but not the Voodoo Rush (tm)) boards are
add-on boards, meant to be used with a regular 2D VGA video
accelerator board. In short, the video output of your regular VGA
board is used as input for the Voodoo Graphics (tm) based add-on
board, which by default passes it through to the display also
connected to the Voodoo Graphics (tm) board. If the Voodoo Graphics
(tm) is used (e.g. by a game), it will disconnect the VGA input
signal, switch the display to a 640x480 fullscreen mode with the
refresh rate configured by SST variables and the application/driver,
and generate the video signal itself. The VGA doesn't need to be aware
of this, and won't be.

This setup has several advantages: free choice of 2D VGA board, which
is an issue with Linux, as XFree86 drivers aren't available for all
chipsets and revisions, and a cost effective migration path to
accelerated 3D graphics. It also has several disadvantages: an
application using the Voodoo Graphics (tm) might not re-enable video
output when crashing, and regular VGA video signal deteoriates in the
the pass-through process.


6.7. What is Texelfx or TMU?

Voodoo Graphics (tm) chipsets have two units. The first one interfaces
the texture memory on the board, does the texture mapping, and
ultimately generates the input for the second unit that interfaces the
framebuffer. This one is called Texelfx, aka Texture Management Unit,
aka TMU. The neat thing about this is that a board can use two Texelfx
instead of only one, like some of the Quantum3D Obsidian boards did,
effectively doubling the processing power in some cases, depending on
the application.

As each Texelfx can address 4MB texture memory, a dual Texelfx setup
has an effective texture cache of up to 8MB. This can be true even if
only one Texelfx is actually needed by a particular application, as
textures can be distributed to both Texelfx, which are used depending
on the requested texture. Both Texelfx are used together to perform
certain operations as trilinear filtering and illumination
texture/lightmap passes (e.g. in glQuake) in a single pass instead of
the two passes that are required with only one Texelfx. To actually
exploit the theoretically available speedup and cache size increase, a
Glide application has to use both Texelfx properly.

The two Texelfx can not be used separately to each draw a textured
triangle at the same time. A triangle is always drawn using whatever
the current setup is, which can be to use both Texelfx for a single
pass operation combining two textures, or one Texelfx for only a
single texture. Each Texelfx can only access its own memory.



6.8. What is a Pixelfx unit?

Voodoo Graphics (tm) chipsets have two units. The second one
interfaces the framebuffer and ultimately generates the depth buffer
and pixel color updates. This one is called Pixelfx. The neat thing
here is that two Pixelfx units can cooperate in SLI mode, like with
some of the Quantum3D Obsidian boards, effectively doubling the frame
rate.



6.9. What is SLI mode?

SLI means "Scanline Interleave". In this mode, two Pixelfx are
connected and render in alternate turns, one handling odd, the other
handling even scanlines of the actual output. Inthis mode, each
Pixelfx stores only half of the image and half of the depth buffer
data in its own local framebuffer, effectively doubling the number of
pixels.

The Pixelfx in question can be on the same board, or on two boards
properly connected. Some Quantum3D Obsidian boards support SLI with
Voodoo Graphics (tm).

As two cards can decode the same PCI addresses and receive the same
data, there is not necessarily additional bus bandwidth required by
SLI. On the other hand, texture data will have to be replicated on
both boards, thus the amount of texture memory effectively stays the
same.



6.10. Is there a single board SLI setup?

There are now two types of Quantum3D SLI boards. The intial setup
used two boards, two PCI slots, and an interconnect (e.g. the Obsidian
100-4440). The later revision which performs identically is contained
on one full-length PCI board (e.g. Obsidian 100-4440SB). Thus a
single board SLI solution is possible, and has been done.



6.11. How much memory? How many buffers?

The most essential difference between different boards using the
Voodoo Graphics (tm) chipset is the amount and organization of memory.
Quantum3D used a three digit scheme to descibe boards. Here is a
slightly modifed one (anticipating Voodoo 2 (tm)). Note that if you
use more than one Texelfx, they need the same amount of texture cache
memory each, and if you combine two Pixelfx, each needs the same
amount of frame buffer memory.
______________________________________________________________________
"SLI / Pixelfx / Texelfx1 / Texelfx2 "
______________________________________________________________________


It means that a common 2MB+2MB board would be a 1/2/2/0 solution, with
the minimally required total 4Mb of memory. A Canopus Pure 3D would be
1/2/4/0, or 6MB. An Obsidian-2220 board with two Texelfx would be
1/2/2/2, and an Obsidian SLI-2440 board would be 2/2/4/4. A fully
featured dual board solution (2 Pixelfx, each with 2 Texelfx and 4MB
frame buffer, each Texelfx 4 MB texture cache) would be 2/4/4/4, and
the total amount of memory would be SLI*(Pixelfx+Texelfx1+Texelfx2),
or 24 MB.

So there.


6.12. Does the Voodoo Graphics (tm) do 24 or 32 bit color?

No. The Voodoo Graphics (tm) architecture uses 16bpp internally. This
is true for Voodoo Graphics (tm), Voodoo Rush (tm) and Voodoo 2 (tm)
alike. Quantum3D claims to implement 22-bpp effective color depth with
an enhanced 16-bpp frame buffer, though.


6.13. Does the Voodoo Graphics (tm) store 24 or 32 bit z-buffer per
pixel?

No. The Voodoo Graphics (tm) architecture uses 16bpp internally for
the depth buffer, too. This again is true for Voodoo Graphics (tm),
Voodoo Rush (tm) and Voodoo 2 (tm) alike. Again, Quantum3D claims that
using the floating point 16-bits per pixel (bpp) depth buffering
provides 22-bpp effective Z-buffer precision.


6.14. What resolutions does the Voodoo Graphics (tm) support?

The Voodoo Graphics (tm) chipset supports up to 4 MB frame buffer
memory. Presuming double buffering and a depth buffer, a 2MB
framebuffer will support a resolution of 640x480. With 4 MB frame
buffer, 800x600 is possible.

Unfortunately 960x720 is not supported. The Voodoo Graphics (tm)
chipset requires that the amount of memory for a particular resolution
must be such that the vertical and horizontal resolutions must be
evenly divisible by 32. The video refresh controller, though can
output any particular resolution, but the "virtual" size required for
the memory footprint must be in dimensions evenly divisible by 32.
So, 960x720 actually requires 960x736 amount of memory, and
960x736x2x3 = 4.04MBytes.

However, using two boards with SLI, or a dual Pixelfx SLI board means
that each framebuffer will only have to store half of the image. Thus
2 times 4 MB in SLI mode are good up to 1024x768, which is the maximum
because of the overall hardware design. You will be able to do
1024x768 tripled buffered with Z, but you will not be able to do e.g.
1280x960 with double buffering.

Note that triple buffering (no VSync synchonization required by the
application), stereo buffering (for interfacing LCD shutters) and
other more demanding setups will severely decrease the available
resolution.



6.15. What texture sizes are supported?

The maximum texture size for the Voodoo Graphics (tm) chipset is
256x256, and you have to use powers of two. Note that for really small
textures (e.g. 16x16) you are better off merging them into a large
texture, and adjusting your effective texture coordinates
appropriately.


6.16. Does the Voodoo Graphics (tm) support paletted textures?

The Voodoo Graphics (tm) hardware and Glide support the palette
extension to OpenGL. The most recent version of Mesa does support the
GL_EXT_paletted_texture and GL_EXT_shared_texture_palette extensions.



6.17. What about overclocking?

If you want to put aside considerations about warranty and
overheating, and want to do overclocking to boost up performance even
further, there is related info out on the web. The basic mechanism is
to use Glide environment variables to adjust the clock.

Note that the actual recommended clock is board dependend. While the
default clock speed is 50 Mhz, the Diamond Monster 3D property sheet
lets you set up a clock of 57 MHz. It all comes down to the design of
a specific board, and which components are used with the Voodoo
Graphics (tm) chipset - most notably access speed of the RAM in
question. If you exceed the limits of your hardware, rendering
artifacts will occur to say the least. Reportedly, 57 MHz usually
works, while 60 MHz or more is already pushing it.

Increasing the clock frequency also means increasing the waste heat
disposed in the chips, in a nonlinear dependency (10% increase in
frequency means a lot larger increase in heating). In consequence, for
permanent overclocking you might want to educate yourself about ways
to add cooling fans to the board in a way that does not affect
warranty. A very recommendable source is the "3Dfx Voodoo Heat Report"
by Eric van Ballegoie, available on the web.



6.18. Where could I get additional info on Voodoo Graphics (tm)?

There is a FAQ by 3Dfx, which should be available at their web site.
You will find retail information at the following locations:
www.3dfx.com and www.quantum3d.com.

Inofficial sites that have good info are "Voodoo Extreme" at
www.ve3d.com, and "Operation 3Dfx" at www.ve3d.com.



7. FAQ: Glide? TexUS?

7.1. What is Glide anyway?

Glide is a proprietary API plus drivers to access 3D graphics
accelerator hardware based on chipsets manufactured by 3Dfx. Glide has
been developed and implemented for DOS, Windows, and Macintosh, and
has been ported to Linux by Daryll Strauss.



7.2. What is TexUS?

In the distribution is a libtexus.so, which is the 3Dfx Interactive
Texture Utility Software. It is an image processing libary and
utility program for preparing images for use with the 3Dfx Interactive
Glide library. Features of TexUS include file format conversion,
MIPmap creation, and support for 3Dfx Interactive Narrow Channel
Compression textures.

The TexUS utility program texus reads images in several popular
formats (TGA, PPM, RGT), generates MIPmaps, and writes the images as
3Dfx Interactive textures files (see e.g. alpha.3df, as found in the
distribution) or as an image file for inspection. For details on the
parameters for texus, and the API, see the TexUS documentation.



7.3. Is Glide freeware?

Nope. Glide is neither GPL'ed nor subject to any other public license.
See LICENSE in the distribution for any details. Effectively, by
downloading and using it, you agree to the End User License Agreement
(EULA) on the 3Dfx web site. Glide is provided as binary only, and you
should neither use nor distribute any files but the ones released to
the public, if you have not signed an NDA. The Glide distribution
including the test program sources are copyrighted by 3Dfx.

The same is true for all the sources in the Glide distribution. In the
words of 3Dfx: These are not public domain, but they can be freely
distributed to owners of 3Dfx products only. No card, No code!


7.4. Where do I get Glide?

The entire 3Dfx SDK is available for download off their public web-
site located at www.3dfx.com/software/download_glide.html. Anything
else 3Dfx publicly released by 3Dfx is nearby on their website, too.

There is also an FTP site, ftp.3dfx.com. The FTP has a longer timeout,
and some of the larger files have been broken into 3 files (approx.
3MB each).



7.5. Is the Glide source available?

Nope. The Glide source is made available only based on a special
agreement and NDA with 3Dfx.


7.6. Is Linux Glide supported?

Currently, Linux Glide is unsupported. Basically, it is provided under
the same disclaimers as the 3Dfx GL DLL (see below).

However, 3Dfx definitely wants to provide as much support as possible,
and is in the process of setting up some prerequisites. For the time
being, you will have to rely on the 3Dfx newsgroup (see below).

In addition, the Quantum3D web page claims that Linux support (for
Obsidian) is planned for both Intel and AXP architecture systems in
2H97.



7.7. Where could I post Glide questions?

There are newsgroups currently available only on the NNTP server
news.3dfx.com run by 3Dfx. This USENET groups are dedicated to 3Dfx
and Glide in general, and will mainly provide assistance for DOS,
Win95, and NT. The current list includes:

______________________________________________________________________
3dfx.events
3dfx.games.glquake
3dfx.glide
3dfx.glide.linux
3dfx.products
3dfx.test
______________________________________________________________________


and the 3dfx.oem.products.* group for specific boards, eg.
3dfx.oem.products.quantum3d.obsidian. Please use
news.3dfx.com/3dfx.glide.linux for all Lnux Glide related questions.

A mailing list dedicated to Linux Glide is in preparation for 1Q98.
Send mail to majordomo@gamers.org, no subject, body of the message
info linux-3dfx to get information about the posting guidelines, the
hypermail archive and how to subscribe to the list or the digest.



7.8. Where to send bug reports?

Currently, you should rely on the newsgroup (see above), that is
news.3dfx.com/3dfx.glide.linux. There is no official support e-mail
set up yet. For questions not specific to Linux Glide, make sure to
use the other newsgroups.


7.9. Who is maintaining it?

3Dfx will appoint an official maintainer soon. Currently, inofficial
maintainer of the Linux Glide port is Daryll Strauss. Please post bug
reports in the newsgroup (above). If you are confident that you found
a bug not previously reported, please mail to Daryll at
daryll@harlot.rb.ca.us


7.10. How can I contribute to Linux Glide?

You could submit precise bug reports. Providing sample programs to be
included in the distribution is another possibility. A major
contribution would be adding code to the Glide based Mesa Voodoo
driver source. See section on Mesa Voodoo below.



7.11. Do I have to use Glide?

Yes. As of now, there is no other Voodoo Graphics (tm) driver
available for Linux. At the lowest level, Glide is the only interface
that talks directly to the hardware. However, you can write OpenGL
code without knowing anything about Glide, and use Mesa with the Glide
based Mesa Voodoo driver. It helps to be aware of the involvement of
Glide for recognizing driver limitations and bugs, though.



7.12. Should I program using the Glide API?

That depends on the application you are heading for. Glide is a
proprietary API that is partly similar to OpenGL or Mesa, partly
contains features only available as EXTensions to some OpenGL
implementations, and partly contains features not available anywhere
but within Glide.

If you want to use the OpenGL API, you will need Mesa (see below).
Mesa, namely the Mesa Voodoo driver, offers an API resembling the well
documented and widely used OpenGL API. However, the Mesa Voodoo driver
is in early alpha, and you will have to accept performance losses and
lack of support for some features.

In summary, the decision is up to you - if you are heading for maximum
performance while accepting potential problems with porting to
non-3Dfx hardware, Glide is not a bad choice. If you care about
maintenance, OpenGL might be the best bet in the long run.



7.13. What is the Glide current version?

The current version of Linux Glide is 2.4. The next version will
probably be identical to the current version for DOS/Windows, which is
2.4.3, which comes in two distributions. Right now, various parts of
Glide are different for Voodoo Rush (tm) (VR) and Voodoo Graphics (tm)
(VG) boards. Thus you have to pick up separate distributions (under
Windows) for VR and VG. The same will be true for Linux. There will
possibly be another chunk of code and another distribution for Voodoo
2 (tm) (V2) boards.

There is also a Glide 3.0 in preparation that will extend the API for
use of triangle fans and triangle strips, and provide better state
change optimization. Support for fans and strips will in some
situations significantly reduce the amount of data sent ber triangle,
and the Mesa driver will benefit from this, as the OpenGL API has
separate modes for this. For a detailed explanation on this see e.g.
the OpenGL documentation.



7.14. Does it support multiple Texelfx already?

Multiple Texelfx/TMU's can be used for single pass trilinear
mipmapping for improvement image quality without performance penalty
in current Linux Glide already. You will need a board with two Texelfx
(that is, one of the appropriate Quantum3D Obsidian boards). The
application needs to specify the use of both Texelfx accordingly, it
does not happen automatically.

Note that because most applications are implemented for consumer
boards with a single Texelfx, they might not query the presence of a
second Texelfx, and thus not use it. This is not a flaw of Glide but
of the application.



7.15. Is Linux Glide identical to DOS/Windows Glide?

The publicly available version of Linux Glide should be identical to
the respective DOS/Windows versions. Delays in releasing the Linux
port of newer DOS/Windows releases are possible.


7.16. Where to I get information on Glide?

There is exhaustive information available from 3Dfx. You could
download it from their home page at
www.3dfx.com/software/download_glide.html. These are for free,
presuming you bought a 3Dfx hardware based board. Please read the
licensing regulations.

Basically, you should look for some of the following:

o Glide Release Notes

o Glide Programming Guide

o Glide Reference Manual

o Glide Porting Guide

o TexUs Texture Utility Software

o ATB Release Notes

o Installing and Using the Obsidian

These are available as Microsoft Word documents, and part of the
Windows Glide distribution, i.e. the self-extracting archive file.
Postscript copies for separate download should be available at
www.3dfx.com as well. Note that the release numbers are not always
in sync with those of Glide.



7.17. Where to get some Glide demos?

You will find demo sources for Glide within the distribution (test
programs), and on the 3Dfx home page. The problem with the latter is
that some require ATB. To port these demos to Linux, the event
handling has to be completely rewritten.

In addition, you might find useful some of the OpenGL demo sources
accompanying Mesa and GLUT. While the Glide API is different from the
OpenGL API, they target the same hardware rendering pipeline.



7.18. What is ATB?

Some of the 3Dfx demo programs for Glide depend not only on Glide but
also on 3Dfx's proprietary Arcade Toolbox (ATB), which is available
for DOS and Win32, but has not been ported for Linux. If you are a
devleoper, the sources are available within the Total Immersion
program, so porting ATB to Linux would be possible.



8. FAQ: Glide and XFree86?


8.1. Does it run with XFree86?

Basically, the Voodoo Graphics (tm) hardware does not care about X.
The X server will not even notice that the video signal generated by
the VGA hardware does not reach the display in single screen
configurations. If your application is not written X aware, Glide
switching to full screen mode might cause problems (see
troubleshooting section). If you do not want the overhead of writing
an X11-aware application, you might want to use SVGA console mode
instead.

So yes, it does run with XFree86, but no, it is not cooperating if you
don't write your application accordingly. You can use the Mesa "window
hack", which will be significantly slower than fullscreen, but still a
lot faster than software rendering (see section below).



8.2. Does it only run full screen?

See above. The Voodoo Graphics (tm) hardware is not window environment
aware, neither is Linux Glide. Again, the experimental Mesa "window
hack" covered below will allow for pasting the Voodoo Graphics (tm)
board framebuffer's content into an X11 window.



8.3. What is the problem with AT3D/Voodoo Rush (tm) boards?

There is an inherent problem when using Voodoo Rush (tm) boards with
Linux: Basically, these boards are meant to be VGA 2D/3D accelerator
boards, either as a single board solution, or with a Voodoo Rush (tm)
based daughterboard used transparently. The VGA component tied to the
Voodoo Rush (tm) is a Alliance Semiconductor's ProMotion-AT3D
multimedia accelerator. To use this e.g. with XFree86 at all, you
need a driver for the AT3D chipset.

There is a mailing list on this, and a web site with FAQ at
www.frozenwave.com/linux-stingray128. Look there for most current
info. There is a SuSE maintained driver at
ftp.suse.com/suse_update/special/xat3d.tgz. Reportedly, the XFree86
SVGA server also works, supporting 8, 16 and 32 bpp. Official support
will probably be in XFree86 4.0. XFree86 decided to prepare an
intermediate XFree86 3.3.2 release as well, which might already
address the issues.

The following XF86Config settings reportedly work.

______________________________________________________________________
# device section settings
Chipset "AT24"
Videoram 4032

# videomodes tested by Oliver Schaertel
# 25.18 28.32 for 640 x 480 (70hz)
# 61.60 for 1024 x 786 (60hz)
# 120 for 1280 x 1024 (66hz)
______________________________________________________________________


In summary, there is nothing prohibiting this except for the fact that
the drivers in XFree86 are not yet finished.

If you want a more technical explanation: Voodoo Rush (tm) support
requires X server changes to support grabbing a buffer area in the
video memory on the AT3D board, as the Voodoo Rush (tm) based boards
need to store their back buffer and z buffer there. This memory
allocation and locking requirement is not a 3Dfx specific problem, it
is also needed e.g. for support of TV capture cards, and is thus under
active development for XFree86. This means changes at the device
dependend X level (thus XAA), which are currently implemented as an
extension to XFree86 DGA (Direct Graphics Access, an X11 extension
proposal implemented in different ways by Sun and XFree86, that is not
part of the final X11R6.1 standard and thus not portable). It might be
part of an XFree86 GLX implementation later on. The currently
distributed X servers assume they have full control of the
framebuffer, and use anything that is not used by the visual region of
the framebuffer as pixmap cache, e.g. for caching fonts.



8.4. What about GLX for XFree86?

There are a couple of problems.

The currently supported Voodoo Graphics (tm) hardware and the
available revision of Linux Glide are full screen only, and not set up
to share a framebuffer with a window environment. Thus GLX or other
integration with X11 is not yet possible.

The Voodoo Rush (tm) might be capable of cooperating with XFree86
(that is, an SVGA compliant board will work with the XFree86 SVGA
server), but it is not yet supported by Linux Glide, nor do S3 or
other XFree86 servers support these boards yet.

In addition, GLX is tied to OpenGL or, in the Linux case, to Mesa.
The XFree86 team is currently working on integrating Mesa with their X
Server. GLX is in beta, XFree86 3.3 has the hooks for GLX. See Steve
Parker's GLX pages at www.cs.utah.edu/~sparker/xfree86-3d/ for the
most recent information. Moreover, there is a joint effort by XFree86
and SuSe, which includes a GLX, see www.suse.de/~sim/. Currently,
Mesa still uses its GLX emulation with Linux.



8.5. Glide and commerical X Servers?

I have not received any mail regarding use of Glide and/or Mesa with
commercial X Servers. I would be interested to get confirmation on
this, especially on Mesa and Glide with a commercial X Server that has
GLX support.



8.6. Glide and SVGA?

You should have no problems running Glide based applications either
single or dual screen using VGA modes. It might be a good idea to set
up the 640x480 resolution in the SVGA modes, too, if you are using a
single screen setup.


8.7. Glide and GGI?

A GGI driver for Glide is under development by Jon M. Taylor, but has
not officially been released and was put on hold till completion of
GGI 0.0.9. For information about GGI see synergy.caltech.edu/~ggi/.
If you are adventurous, you might find the combination of XGGI (a GGI
based X Server for XFree86) and GGI for Glide an interesting prospect.
There is also a GGI driver interfacing the OpenGL API; tested with
unaccelerated Mesa. Essentially, this means X11R6 running on a Voodoo
Graphics (tm), using either Mesa or Glide directly.



9. FAQ: OpenGL/Mesa?



9.1. What is OpenGL?

OpenGL is an immediate mode graphics programming API originally
developed by SGI based on their previous proprietary Iris GL, and
became in industry standard several years ago. It is defined and
maintained by the Architectural Revision Board (ARB), an organization
that includes members as SGI, IBM, and DEC, and Microsoft.

OpenGL provides a complete feature set for 2D and 3D graphics
operations in a pipelined hardware accelerated architecture for
triangle and polygon rendering. In a broader sense, OpenGL is a
powerful and generic toolset for hardware assisted computer graphics.



9.2. Where to get additional information on OpenGL?

The official site for OpenGL maintained by the members of the ARB, is
www.opengl.org,

A most recommended site is Mark Kilgard's Gateway to OpenGL Info at
reality.sgi.com/mjk_asd/opengl-links.html: it provides pointers to
book, online manual pages, GLUT, GLE, Mesa, ports to several OS, tons
of demos and tools.

If you are interested in game programming using OpenGL, there is the
OpenGL-GameDev-L@fatcity.com at Listserv@fatcity.com. Be warned, this
is a high traffic list with very technical content, and you will
probably prefer to use procmail to handle the 100 messages per day
coming in. You cut down bandwidth using the SET OpenGL-GameDev-L
DIGEST command. It is also not appropriate if you are looking for
introductions. The archive is handled by the ListServ software, use
the INDEX OpenGL-GameDev-L and GET OpenGL-GameDev-L "filename"
commands to get a preview before subscribing.



9.3. Is Glide an OpenGL implementation?

No, Glide is a proprietary 3Dfx API which several features specific to
the Voodoo Graphics (tm) and Voodoo Rush (tm). A 3Dfx OpenGL is in
preparation (see below). Several Glide features would require
EXTensions to OpenGL, some of which already found in other
implementations (e.g. paletted textures).

The closest thing to a hardware accelerated Linux OpenGL you could
currently get is Brian Paul's Mesa along with David Bucciarelli's Mesa
Voodoo driver (see below).



9.4. Is there an OpenGL driver from 3Dfx?

Both the 3Dfx website and the Quantum3D website announced OpenGL for
Voodoo Graphics (tm) to be available 4Q97. The driver is currently in
Beta, and accessible only to registered deverloper's under written
Beta test agreement.

A linux port has not been announced yet.



9.5. Is there a commercial OpenGL for Linux and 3Dfx?

I am not aware of any third party commercial OpenGL that supports the
Voodoo Graphics (tm). Last time I paid attention, neither MetroX nor
XInside OpenGL did.



9.6. What is Mesa?

Mesa is a free implementation of the OpenGL API, designed and written
by Brian Paul, with contributions from many others. Its performance is
competitive, and while it is not officially certified, it is an almost
fully compliant OpenGL implementation conforming to the ARB
specifications - more complete than some commercial products out,
actually.



9.7. Does Mesa work with 3Dfx?

The latest Mesa MesaVer; release works with Linux Glide 2.4. In fact,
support was included in earlier versions, however, this driver is
still under development, so be prepared for bugs and less than optimal
performance. It is steadily improving, though, and bugs are usually
fixed very fast.

You will need to get the Mesa library archive from the
iris.ssec.wisc.edu FTP site. It is recommended to subscribe to the
mailing list as well, especially when trying to track down bugs,
hardware, or driver limitations. Make sure to get the most recent
distribution. A Mesa-3.0 is in preparation.



9.8. How portable is Mesa with Glide?

It is available for Linux and Win32, and any application based on Mesa
will only have the usual system specific code, which should usually
mean XWindows vs. Windows, or GLX vs. WGL. If you use e.g. GLUT or Qt,
you should get away with any system specifics at all for virtually
most applications. There are only a few issues (like sampling relative
mouse movement) that are not adressed by the available portable GUI
toolkits.

Mesa/Glide is also available for DOS. The port which is 32bit DOS is
maintained by Charlie Wallace and kept up to date with the main Mesa
base. See www.geocities.com/~charlie_x/.for the most current releases.



9.9. Where to get info on Mesa?

The Mesa home page is at www.ssec.wisc.edu/~brianp/Mesa.html. There
is an archive of the Mesa mailing list. at www.iqm.unicamp.br/mesa/.
This list is not specific to 3Dfx and Glide, but if you are interested
in using 3Dfx hardware to accelerate Mesa, it is a good place to
start.


9.10. Where to get information on Mesa Voodoo?

For latest information on the Mesa Voodoo driver maintained by David
Bucciarelli tech.hmw@plus.it see the home page at www-
hmw.caribel.pisa.it/fxmesa/.

9.11. Does Mesa support multitexturing?

Not yet (as of Mesa 2.6), but it is on the list. In Mesa you will
probably have to use the OpenGL EXT_multitexture extension once it is
available. There is no final specification for multitextures in
OpenGL, which is supposed to be part of the upcoming OpenGL 1.2
revision. There might be a Glide driver specific implementation of the
extension in upcoming Mesa releases, but as long as only certain
Quantum3D Obsidian boards come with multiple TMU's, it is not a top
priority. This will surely change once Voodoo 2 (tm) based boards are
in widespread use.



9.12. Does Mesa support single pass trilinear mipmapping?

Multiple TMU's should be used for single pass trilinear mipmapping for
improvement image quality without performance penalty in current Linux
Glide already. Mesa support is not yet done (as of Mesa 2.6), but is
in preparation.



9.13. What is the Mesa "Window Hack"?

The most recent revisions of Mesa contain an experimental feature for
Linux XFree86. Basically, the GLX emulation used by Mesa copies the
contents of the Voodoo Graphics (tm) board's most recently finished
framebuffer content into video memory on each glXSwapBuffers call.
This feature is also available with Mesa for Windows.

This obviously puts some drain on the PCI, doubled by the fact that
this uses X11 MIT SHM, not XFree86 DGA to access the video memory. The
same approach could theoretically be used with e.g. SVGA. The major
benefit is that you could use a Voodoo Graphics (tm) board for
accelerated rendering into a window, and that you don't have to use
the VGA passthrough mode (video output of the VGA board deteoriates in
passing through, which is very visible with high end monitors like
e.g. EIZO F784-T).

Note that this experimental feature is NOT Voodoo Rush (tm) support by
any means. It applies only to the Voodoo Graphics (tm) based boards.
Moreover, you need to use a modified GLUT, as interfacing the window
management system and handling the events appropriately has to be done
by the application, it is not handled in the driver.

Make really sure that you have enabled the following environment
variables:

______________________________________________________________________
export SST_VGA_PASS=1 # to stop video signal switching
export SST_NOSHUTDOWN=1 # to stop video signal switching
export MESA_GLX_FX="window" # to initiate Mesa window mode
______________________________________________________________________


If you manage to forget one of the SST variables, your VGA board will
be shut off, and you will loose the display (but not the actual X). It
is pretty hard to get that back being effectively blind.

Finally, note that the libMesaGL.a (or .so) library can contain
multiple client interfaces. I.e. the GLX, OSMesa, and fxMesa (and
even SVGAMesa) interfaces call all be compiled into the same
libMesaGL.a. The client program can use any of them freely, even
simultaneously if it's careful.



9.14. How about GLUT?

Mark Kilgard's GLUT distribution is a very good place to get sample
applications plus a lot of useful utilities. You will find it at
reality.sgi.com/mjk_asd/glut3/, and you should get it anyway. The
current release is GLUT 3.6, and discussion on a GLUT 3.7 (aka
GameGLUT) has begun. Note that Mark Kilgard has left SGI recently, so
the archive might move some time this year - for the time being it
will be kept at SGI.

There is also a GLUT mailing list, glut@perp.com. Send mail to
majordomo@perp.com, with the (on of the) following in the body of your
email message:

______________________________________________________________________
help
info glut
subscribe glut
end
______________________________________________________________________



As GLUT handles double buffers, windows, events, and other operations
closely tied to hardware and operating system, using GLUT with Voodoo
Graphics (tm) requires support, which is currently in development
within GLX for Mesa. It already works for most cases.



10. FAQ: But Quake?

10.1. What about that 3Dfx GL driver for Quake?

The 3Dfx Quake GL, aka mini-driver, aka miniport, aka Game GL, aka
3Dfx GL alpha, implemented only a Quake-specific subset of OpenGL (see
http://www.cs.unc.edu/~martin/3dfx.html for an inofficial list of
supported code paths). It is not supported, and not updated anymore.
It was a Win32 DLL (opengl32.dll) released by 3Dfx and was available
for Windows only. This DLL is not, and will not be ported to Linux.


10.2. Is there a 3Dfx based glQuake for Linux?

Yes. A Quake linuxquake v0.97 binary has been released based on Mesa
with Glide. The Quake2 q2test binary for Linux and Voodoo Graphics
(tm) has been made available as well. A full Quake2 for Linux was
released in January 1998, with linuxquake2-3.10. Dave "Zoid" Kirsch is
the official maintainer of all Linux ports of Quake, Quakeworld, and
Quake2, including all the recent Mesa based ports. Note that all Linux
ports, including the Mesa based ones, are not officially supported by
id Software.

See ftp.idsoftware.com/idstuff/quake/unix/ for the latest releases.



10.3. Does glQuake run in an XFree86 window?

A revision of Mesa and the Mesa-based Linux glQuake is in preparation.
Mesa already does support this by GLX, but Linux glQuake does not use
GLX.



10.4. Known Linux Quake problems?

Here is an excerpt, as of January 7th, 1998. I omitted most stuff not
specific to &3Dfx; hardware.

o You really should run Quake2 as root when using the SVGALib and/or
GL renders. You don't have to run as root for the X11 refresh, but
the modes on the mouse and sound devices must be read/writable by
whatever user you run it as. Dedicated server requires no special
permissions.

o X11 has some garbage on the screen when 'loading'. This is normal
in 16bit color mode. X11 doesn't work in 24bit (TrueColor). It
would be very slow in any case.

o Some people are experiencing crashes with the GL renderer. Make
sure you install the libMesa that comes with Quake2! Older versions
of libMesa don't work properly.

o If you are experience video 'lag' in the GL renderer (the frame
rate feels like it's lagging behind your mouse movement) type
"gl_finish 1" in the console. This forces update on a per frame
basis.

o When running the GL renderer, make sure you have killed selection
and/or gpm or the mouse won't work as they won't "release" it while
Quake2 is running in GL mode.


10.5. Know Linux Quake security problems?

As Dave Kirsch posted on January 28th, 1998: an exploit for Quake2
under Linux has been published. Quake2 is using shared libraries.
While the READMRE so far does not specifically mention it, note that
Quake2 should not be setuid.

If you want to use the ref_soft and ref_gl renderers, you should run
Quake2 as root. Do not make the binary setuid. You can only run both
those renderers at the console only, so being root is not that much of
an issue.

The X11 render does not need any root permissions (if /dev/dsp is
writable by others for sound). The dedicated server mode does not
need to be root either, obviously.

Problems such as root requirements for games has been sort of a sore
spot in Linux for a number of years now. This is one of the goals that
e.g. GGI is targetting to fix. A ref_ggi might be supported in the
near future.


10.6. Does LinuxQuake use multitexturing?

To my understadnding, glQuake will use a multitexture EXTension if the
OpenGL driver in question offers it. The current Mesa implementation
and the Glide driver for Linux do not yet support this extension, so
for the time being the answer is no. See section on Mesa and
multitexturing for details.
10.7. Where can I get current information on Linux glQuake?

Try some of these sites: the "The Linux Quake Resource" at
linuxquake.telefragged.com, or the "Linux Quake Page" at
www.planetquake.com/threewave/linux/. Alternatively, you could look
for Linux Quake sites in the "SlipgateCentral" database at
www.slipgatecentral.com.



11. FAQ: Troubleshooting?

11.1. Has this hardware been tested?

See hardware requirements list above. I currently do not maintain a
conclusive list of vendors and boards, as no particular board specific
problems have been verified. Currently, only 3Dfx and Quantum3D
provide boards for testing to the developers, so Quantum3D consumer
boards are a safe bet. Every other Voodoo Graphics (tm) based board
should work, too. I have reports regarding the Orchid Righteous 3D,
Guillemot Maxi 3D Gamer, and Diamond Monster 3D.

If you are a board manufacturer who wants to make sure his Voodoo
Graphics (tm), Voodoo Rush (tm) or Voodoo 2 (tm) boards work with
upcoming releases of Linux, Xfree86, Linux Glide and/or Mesa, please
contact me, and I will happily forward your request to the persons
maintaining the drivers in question. If you are interested in support
for Linux Glide on other then the PC platfrom, e.g. DEC Alpha, please
contact the maintainer of Linux Glide Daryll Strauss, at
daryll@harlot.rb.ca.us



11.2. Failed to change I/O privilege?

You need to be root, or setuid your application to run a Glide based
application. For DMA, the driver accesses /dev/mem, which is not
writeable for anybody but root, with good reasons. See the README in
the Glide distribution for Linux.



11.3. Does it work without root privilege?

There are compelling case where the setuid requirement is a problem,
obviously. There are currently solutions in preparation, which require
changes to the library internals itself.



11.4. Displayed images looks awful (single screen)?

If you are using the analog pass through configuration, the common
SVGA or X11 display might look pretty bad. You could try to get a
better connector cable than the one provided with the accelerator
board (the ones delivered with the Diamond Monster 3D are reportedly
worse then the one accompanying the Orchid Righteous 3D), but up to a
degree there will inevitably be signal loss with an additional
transmission added.

If the 640x480 full screen image created by the accelerator board does
look awful, this might indicate a real hardware problem. You will have
to contact the board manufacturer, not 3Dfx for details, as the
quality of the video signal has nothing to do with the accelerator -
the board manufacturer chooses the RAMDAC, output drivers, and other
components responsible.



11.5. The last frame is still there (single or dual screen)?

You terminated your application with Ctrl-C, or it did not exit
normally. The accelerator board will dutifully provide the current
content of the framebuffer as a video signal unless told otherwise.



11.6. Powersave kicks in (dual screen)?

When you application terminates in dual screen setups, the accelerator
board does not provide video output any longer. Thus powersave kicks
each time. To avoid this, use

______________________________________________________________________
setenv SST_DUALSCREEN 1
______________________________________________________________________



11.7. My machine seem to lock (X11, single screen)?

If you are running X when calling a Glide application, you probably
moved the mouse out of the window, and the keyboard inputs do not
reach the application anymore.

If you application is supposed to run concurrently with X11, it is
recommend to expose a full screen window, or use the XGrabPointer and
XGrabServer functions to redirect all inputs to the application while
the X server cannot access the display. Note that grabbing all input
with XGrabPointer and XGrabServer does not qualify as well-behaved
application, and that your program might block the entire system.

If you experience this problem without running X, be sure that there
is no hardware conflict (see below).


11.8. My machine locks (single or dual screen)?

If the system definitely does not respond to any inputs (you are
running two displays and know about the loss of focus), you might
experience a more or less subtle hardware conflict. See installation
troubleshooting section for details.

If there is no obvious address conflict, there might still be other
problems (below). If you are writing your own code the most common
reason for locking is that you didn't snap your vertices. See the
section on snapping in the Glide documentation.


11.9. My machine locks (used with S3 VGA board)?

It is possible you have a problem with memory region overlap specific
to S3. There is some info and a patch to the so-called S3 problem in
the 3Dfx web site, but these apply to Windows only. To my
understanding, the cause of the problem is that some S3 boards (older
revisions of Diamond Stealth S3 968) reserve more memory space than
actually used, thus the Voodoo Graphics (tm) has to be mapped to a
different location. However, this has not been reported as a problem
with Linux, and might be Windows-specific.
11.10. No address conflict, but locks anyway?

If you happen to use a motherboard with non-standard or incomplete PCI
support, you could try to shuffle the boards a bit. I am running an
ASUS TP4XE that has that non-standard modified "Media Slot", i.e. PCI
slot4 with additional connector for ASUS-manufactured SCSI/Sound combo
boards, and I experienced severe problems while running a Diamond
Monster 3D in that slot. The system operates flawlessly since I put
the board in one of the regular slots.



11.11. Mesa runs, but does not access the board?

Be sure that you recompiled all the libraries (including the toolkits
the demo programs use - remember that GLUT does not yet support Voodoo
Graphics (tm)), and that you removed the older libraries, run
ldconfig, and/or set your LD_LIBRARY_PATH properly. Mesa supports
several drivers in parallel (you could use X11 SHM, off screen
rendering, and Mesa Voodoo at the same time), and you might have to
create and switch contexts explicitely (see MakeCurrent function) if
the Voodoo Graphics (tm) isn't chosen by default.



11.12. Resetting dual board SLI?

If a Quantum 3D Obsidian board using in an SLI setup exits abruptly
(i.e., the application crashes, or is aborted by user), the boards are
left in an undefined state. With the dual-board set, you can run a
program called resetsli to reset them. Until you run the resetsli
program, you will not be able to re-initialize the Obsidian board.



11.13. Resetting single board SLI?

The resetsli program mentioned above does not yet work with a single
board Obsidian SLI (e.g. the Obsidian 100-4440SB). You will have to
reboot your system by reset in order to reset the board.

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