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\ \ __ \ \ \ \ \ \ \ /'__`\ /'_ `\/\`'__\/ __`\
\ \ \/\ \ \_\ \_ \_\ \_/\ __//\ \L\ \ \ \//\ \L\ \
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\/_/\/_/\/____/\/____/\/____/\/___L\ \/_/ \/___/
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\_/__/ Version 3.0
A game programming library
By Shawn Hargreaves, 1994/97
#include <std_disclaimer.h>
"I do not accept responsibility for any effects, adverse or otherwise,
that this code may have on you, your computer, your sanity, your dog,
and anything else that you can think of. Use it at your own risk."
======================================
============ Introduction ============
======================================
Allegro is a library of functions for use in computer games, written for
the djgpp compiler in a mixture of C and assembly language. This is
version 3.0: see the NEWS file for a list of differences from the
previous release.
According to the Oxford Companion to Music, Allegro is the Italian for
"quick, lively, bright". Once upon a time it was also an acronym for
"Atari Low Level Game Routines", but it is a long time since I did any
programming on the Atari, and the name is pretty much the only thing left
of the original Atari code.
==================================
============ Features ============
==================================
Supports VGA mode 13h, mode-X (twenty two tweaked VGA resolutions plus
unchained 640x400 Xtended mode), and SVGA modes with 8, 15, 16, 24, and
32 bit color depths. Uses VESA 2.0 linear framebuffers if they are
available, and also contains register level drivers for ATI, Cirrus,
Paradise, S3, Trident, Tseng, and Video-7 cards.
Drawing functions including putpixel, getpixel, lines, rectangles, flat
shaded, gouraud shaded, and texture mapped polygons, circles, floodfill,
bezier splines, patterned fills, masked, run length encoded, and compiled
sprites, blitting, bitmap scaling and rotation, translucency/lighting,
and text output with proportional fonts. Supports clipping, and can draw
directly to the screen or to memory bitmaps of any size.
Hardware scrolling, mode-X split screens, and palette manipulation.
FLI/FLC animation player.
Plays background MIDI music and up to 32 simultaneous sound effects.
Samples can be looped (forwards, backwards, or bidirectionally), and the
volume, pan, pitch, etc, can be adjusted while they are playing. The MIDI
player responds to note on, note off, main volume, pan, pitch bend, and
program change messages, using the General MIDI patch set and drum
mappings. Currently supports Adlib, SB, SB Pro, SB16, AWE32, MPU-401, and
software wavetable MIDI.
Easy access to the mouse, keyboard, joystick, and high resolution timer
interrupts, including a vertical retrace interrupt simulator.
Routines for reading and writing LZSS compressed files.
Multi-object data files and a grabber utility.
Math functions including fixed point arithmetic, lookup table trig, and
3d vector/matrix manipulation.
GUI dialog manager and file selector.
===================================
============ Copyright ============
===================================
Allegro is swap-ware. You may use, modify, redistribute, and generally
hack it about in any way you like, but if you do you must send me
something in exchange. This could be a complimentary copy of a game, an
addition or improvement to Allegro, a bug report, some money (this is
particularly encouraged if you use Allegro in a commercial product), or
just a copy of your autoexec.bat if you don't have anything better. If
you redistribute parts of Allegro or make a game using it, it would be
nice if you mentioned me somewhere in the credits, but if you just want
to pinch a few routines that is OK too. I'll trust you not to rip me off.
============================================
============ Supported hardware ============
============================================
The bare minimum you need to use Allegro is a 386 with a VGA graphics
card, but a 486 is strongly recommended. To get into SVGA modes you will
need a compatible SVGA card, which means either one of the cards that is
supported directly, or a card with a working VESA driver. If you have a
VESA 2.0 implementation such as UniVBE (which you can get from the
Display Doctor link on http://www.scitechsoft.com/), you are fine just
using that. If you don't, beware. For one thing, everything will be much
slower if Allegro can't use the sexy VBE 2.0 features. For another, I
could go on all day telling horror stories about the buggy and generally
just pathetic VESA implementations that I've come across. If you are
having trouble with the SVGA modes, try getting a copy of UniVBE and see
if that clears things up (it probably will: SciTech usually get these
things right).
On the sound front, Allegro supports sample playback on the SB (mono),
the SB Pro (stereo), and the SB16. It has MIDI drivers for the OPL2 FM
synth (Adlib and SB cards), the OPL3 (Adlib Gold, SB Pro-II and above),
the pair of OPL2 chips found in the SB Pro-I, the AWE32 EMU8000 chip, the
raw SB MIDI output, and the MPU-401 interface, plus it can emulate a
wavetable MIDI synth in software, running on top of any of the supported
digital soundcards. If you feel like coming up with drivers for any other
hardware, they would be much appreciated.
You may notice that this release contains some code for building a Linux
version, but don't bother trying this: it won't work! A _lot_ more work
is needed before Allegro will be usable under Linux.
There is also the first part of a VBE/AF driver in this package. VBE/AF
is an extension to the VBE 2.0 API which provides a standard way of
accessing hardware accelerator features. My driver implements all the
basic mode set and bank switch functions, so it works as well as the
regular VESA drivers, but it doesn't yet support any accelerated drawing
operations. This is because SciTech have, so far, only implemented VBE/AF
on the ATI Mach64 chipset, and I don't have access to a Mach64. I'll
finish the driver as soon as they implement VBE/AF on the Matrox Mystique.
============================================
============ Installing Allegro ============
============================================
To conserve space I decided to make this a source-only distribution, so
you will have to compile Allegro before you can use it. To do this you
should:
- Go to wherever you want to put your copy of Allegro (your main djgpp
directory would be fine, but you can put it somewhere else if you
prefer), and unzip everything. Allegro contains several subdirectories,
so you must specify the -d flag to pkunzip.
- If you are using PGCC, uncomment the definition of PGCC at the top of
the makefile, or set the environment variable "PGCC=1".
- Type "cd allegro", followed by "make". Then go do something
interesting while everything compiles. If all goes according to plan
you will end up with a bunch of test programs, some tools like the
grabber, and the library itself, liballeg.a.
If you have any trouble with the build, look at faq.txt for the
solutions to some of the more common problems.
- If you want to use the sound routines or a non-US keyboard layout, it
is a good idea to set up an allegro.cfg file: see below.
- If you want to read the Allegro documentation with the Info viewer
or the Rhide online help system, edit the file djgpp\info\dir, and in
the menu section add the lines:
* Allegro: (allegro.inf).
The Allegro game programming library
- If you want to create the HTML documentation as one large allegro.html
file rather than splitting it into sections, edit docs\allegro._tx,
remove the @multiplefiles statement from line 8, and run make again.
To use Allegro in your programs you should:
- Put the following line at the beginning of all C or C++ files that use
Allegro:
#include <allegro.h>
- If you compile from the command line or with a makefile, add '-lalleg'
to the end of the gcc command, eg:
gcc foo.c -o foo.exe -lalleg
- If you are using Rhide, go to the Options/Libraries menu, type 'alleg'
into the first empty space, and make sure the box next to it is checked.
See allegro.txt for details of how to use the Allegro functions, and how
to build a debug version of the library.
=======================================
============ Configuration ============
=======================================
When Allegro initialises the keyboard and sound routines it reads
information about your hardware from a file called allegro.cfg or sound.cfg.
If this file doesn't exist it will autodetect (ie. guess :-) You can write
your config file by hand with a text editor, or you can use the setup
utility program.
Normally setup.exe and allegro.cfg will go in the same directory as the
Allegro program they are controlling. This is fine for the end user, but it
can be a pain for a programmer using Allegro because you may have several
programs in different directories and want to use a single allegro.cfg for
all of them. If this is the case you can set the environment variable
ALLEGRO to the directory containing your allegro.cfg, and Allegro will look
there if there is no allegro.cfg in the current directory.
The mapping tables used to store different keyboard layouts are stored in a
file called keyboard.dat. This must either be located in the same directory
as your Allegro program, or in the directory pointed to by the ALLEGRO
environment variable. If you want to support different international
keyboard layouts, you must distribute a copy of keyboard.dat along with your
program.
See allegro.txt for details of the config file format.
================================================
============ Notes for the musician ============
================================================
The OPL2 synth chip can provide either nine voice polyphony or six voices
plus five drum channels. How to make music sound good on the OPL2 is left as
an exercise for the reader :-) On an SB Pro or above you will have eighteen
voices, or fifteen plus drums. Allegro decides whether to use drum mode
individually for each MIDI file you play, based on whether it contains any
drum sounds or not. If you have an orchestral piece with just the odd cymbal
crash, you might be better removing the drums altogether as that will let
Allegro use the non-drum mode and give you an extra three notes polyphony.
When Allegro is playing a MIDI file in looped mode, it jumps back to the
start of the file when it reaches the end of the piece. To control the exact
loop point, you may need to insert a dummy marker event such as a controller
message on an unused channel.
All the OPL chips have very limited stereo capabilities. On an OPL2,
everything is of course played in mono. On the SB Pro-I, sounds can only be
panned hard left or right. With the OPL3 chip in the SB Pro-II and above,
they can be panned left, right, or centre. I could use two voices per note
to provide more flexible panning, but that would reduce the available
polyphony and I don't want to do that. So don't try to move sounds around
the stereo image with streams of pan controller messages, because they will
jerk horribly. It is also worth thinking out the panning of each channel so
that the music will sound ok on both SB Pro-I and OPL3 cards. If you want a
sound panned left or right, use a pan value less than 48 or greater than 80.
If you want it centred, use a pan value between 48 and 80, but put it
slightly to one side of the exactly central 64 to control which speaker will
be used if the central panning isn't possible.
The DIGMID wavetable driver uses standard GUS format .pat files, and you
will need a collection of such instruments before you can use it. This can
either be in the standard GUS format (a set of .pat files and a default.cfg
index), or a patches.dat file as produced by the pat2dat utility. You can
also use pat2dat to convert AWE32 SoundFont banks into the patches.dat
format, and if you list some MIDI files on the command line it will filter
the sample set to only include the instruments that are actually used by
those tunes, so it can be useful for getting rid of unused instruments when
you are preparing to distribute a game. See the Allegro website for some
links to suitable sample sets.
The DIGMID driver normally only loads the patches needed for each song when
the tune is first played. This reduces the memory usage, but can result in a
longish delay the first time you play each MIDI file. If you prefer to load
the entire patch set in one go, call the load_midi_patches() function.
The CPU sample mixing code can support between 1 and 32 voices, going up in
powers of two (ie. either 1, 2, 4, 8, 16, or 32 channels). By default it
provides 8 digital voices, or 8 digital plus 24 MIDI voices (a total of 32)
if the DIGMID driver is in use. But the more voices, the lower the output
volume and quality, so you may wish to change this by calling the
reserve_voices() function or setting the digi_voices and midi_voices
parameters in allegro.cfg.
======================================
============ Contact info ============
======================================
WWW: http://www.talula.demon.co.uk/allegro/
Mailing list: allegro@canvaslink.com. To add or remove yourself,
write to listserv@canvaslink.com with the text
"subscribe allegro yourname" or "unsubscribe
allegro" in the body of your message.
Usenet: Try the djgpp newsgroup, comp.os.msdos.djgpp
IRC: #allegro channel on EFnet
My email: shawn@talula.demon.co.uk
Snail mail: Shawn Hargreaves,
1 Salisbury Road,
Market Drayton,
Shropshire,
England, TF9 1AJ.
Telephone: UK 01630 654346
On Foot: Coming down Shrewsbury Road from the town centre,
turn off down Salisbury Road and it is the first
house on the left.
If all else fails: 52 deg 54' N
2 deg 29' W
The latest version of Allegro can always be found on the Allegro
homepage, http://www.talula.demon.co.uk/allegro/.
