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Freedom
02-22-2004, 01:55 PM
Anyone have the grabber text file or any info on how to use it?

ShadowTiger
02-22-2004, 02:05 PM
It's actually not that hard. There are only a few things that you'll need to know if you have some sound files to replace some. (In other words, making a custom SFX.dat. ) You just import things, via a right click menu, I believe. The important thing to know, is that even though we don't really know how to operate it to its fullest, if you want to import and export sounds, the buttons are REALLY right there, and we just have to find them, click on them, etc.

So I'm sorry I can't be of much help, but we CAN do this NOW. I've done it, and it's not difficult. Just keep opening menus until you see the import or export feature.

Just make sure you've made your backups. ;)

Freedom
02-22-2004, 02:56 PM
Just make sure you've made your backups.


backups of the sfx files you mean, or is there a danger of it crashing my whole system?

and how do you determine what sound goes where?
like match a sound to a certain event or function?

I'm sure that I'll figure out most of it as I go, but I was looking for some info to get started, I've never done anything with it.

ShadowTiger
02-22-2004, 02:59 PM
(Replies in bold.)
backups of the sfx files you mean, or is there a danger of it crashing my whole system?
The SFX files. :p
and how do you determine what sound goes where?
like match a sound to a certain event or function?
Oh. Simple enough. That's where the backup comes into play. They're all named after their function, AND, you can PLAY the sound if you'de like, probably by hitting spacebar on them. So you can hear their function, so you can then replace them with the thing you want.
I'm sure that I'll figure out most of it as I go, but I was looking for some info to get started, I've never done anything with it.
Yep, good luck. It's not so hard, you'll see. ;)

Melonhead
02-22-2004, 03:39 PM
__ ___ ___ ___ ___ _ _ ___ ___
| \ |_| | |_| |__ | | |__ [_
|_/ | | | | | | | |__ |__ __]


by Shawn Hargreaves



An Allegro datafile is a bit like a zip file in that it consists of lots of
different pieces of data stuck together one after another, and optionally
compressed. This means that your game doesn't have to clutter up the disk
with hundreds of tiny files, and it makes programming easier because you can
load everything with a single function call at program startup. Another
benefit is that the LZSS file compression algorithm works much better with
one large file than with many small ones.

Datafiles have the extension .dat, and can be created and edited with the
graphical grabber program or the command line dat utility. They can be
stored as separate files and loaded into memory by the load_datafile()
function, or you can use dat2s to convert them into asm code which can then
be linked directly into your executable.

Each datafile contains a number of objects, of varying types. Object types
are represented by 32 bit integer ID's, which are interpreted as four
character ASCII strings. These ID's can be constructed with the DAT_ID()
macro, for example a DATA object is represented by DAT_ID('D','A','T','A'),
or you can use the predefined DAT_* constants for the standard data types:

DAT_FILE - "FILE"
A datafile, which contains a list of other objects. Datafile objects
can be nested inside other datafiles, allowing you to create
hierarchical structures of any depth.

DAT_DATA - "DATA"
A block of binary data. Allegro treats all unknown types as binary
data objects, so you don't need to use this ID: you can create custom
object formats using whatever ID's you like.

DAT_FONT - "FONT"
A font.

DAT_SAMPLE - "SAMP"
A digital sound sample.

DAT_MIDI - "MIDI"
A MIDI file.

DAT_PATCH - "PAT "
A Gravis patch (MIDI instrument).

DAT_FLI - "FLIC"
An FLI or FLC animation.

DAT_BITMAP - "BMP "
A bitmap.

DAT_RLE_SPRITE - "RLE "
A run length encoded sprite.

DAT_C_SPRITE - "CMP "
A compiled sprite.

DAT_XC_SPRITE - "XCMP"
A mode-X compiled sprite.

DAT_PALETTE - "PAL "
A 256 color palette.

DAT_PROPERTY - "prop"
An object property (see below). You will never directly encounter this
object type, but you should be aware that it is treated specially by
the datafile code.

DAT_INFO - "info"
The grabber utility uses this object to store information about the
datafile. Like property objects, you ought never to encounter it, but
you should avoid using the ID for any custom object formats you create.

DAT_END - -1
Special marker used to indicate the end of a datafile.

Each object can have any number of properties attached to it. These are
ASCII strings describing attributes of the object, such as its name and
where it came from. Like the objects themselves, properties are identified
by 32 bit integer ID's which are constructed from four character strings by
the DAT_ID() macro. Allegro defines the standard properties:

"NAME"
The name of the object.

"ORIG"
The object's origin, ie. the name of the file from which it was
grabbed.

"DATE"
A timestamp, used by the update command in the grabber and dat
utilities. This is the modification time of the file from which the
object was grabbed, in "m-dd-yyyy, hh:mm" format.

"XPOS"
For bitmap objects which were grabbed from part of a larger image, the
x position of the origin within the parent bitmap.

"YPOS"
For bitmap objects which were grabbed from part of a larger image, the
y position of the origin within the parent bitmap.

"XSIZ"
For bitmap objects which were grabbed from part of a larger image, the
width of the selected region.

"YSIZ"
For bitmap objects which were grabbed from part of a larger image, the
height of the selected region.

"XCRP"
For autocropped bitmap objects, the amount of cropping on the left of
the image.

"YCRP"
For autocropped bitmap objects, the amount of cropping at the top of
the image.

The properties "HNAM", "HPRE", "XGRD", "YGRD", "BACK", "DITH" and "PACK", are
also used internally by the grabber, but you can use whatever other ID's you
like to store custom information about your objects.



===================================
======== Using the Grabber ========
===================================


The grabber accepts a few different commandline options:

'-bpp'
Sets the color depth, eg. -8, -16, -32.

'-WxH'
Sets the screen resolution, eg. -320x200, -1024x768

'-nosound'
Disables audio output.

'-pkey'
Use 'key' as the datafile password.

'filename.dat'
Loads the named datafile.

Various options can be set using the buttons and text fields at the top of
the screen. You can edit the name of the datafile, the name of the header
file for exporting object indexes (leave this blank if you don't want to
output a header), and the prefix string for the header file definitions. You
can change the grid settings for grabbing bitmaps, and alter the compression
mode (see below). You can enable or disable backups: if this box is checked,
the old version will be renamed to a .bak extension when datafiles are saved.
You can also turn dithering on (this can improve the image quality when you
reduce graphics from 15, 16, 24 or 32-bit color to 8-bit color and from 24 or
32-bit color to 15 or 16-bit color) and enable transparency preserving (this
will ensure that the masked areas in bitmaps stay exactly the same through
color conversion).

The contents of the datafile are listed in the box at the bottom left of the
screen, and can be selected with the mouse or arrow keys. Multiple objects
can be selected by holding down the shift or control keys while you click
on the list or move the cursor. The selected object can be edited with
commands from the Object menu, or using the shortcut menu produced by
pressing Esc or right-clicking on an object. Double-clicking on an object
performs a function which varies depending on the type of the object.
Bitmaps are displayed full-screen (use the plus and minus keys to zoom in
and out), samples and MIDI files are played, palettes are selected (meaning
that they will be used when displaying and exporting bitmaps), and fonts can
be edited by adding and removing specific character ranges.

New objects can be created using the menus or by pressing Insert while the
item list has the input focus. To make nested datafiles, create a FILE
object (New/Datafile), and select it before inserting other objects.

To insert information into a datafile you must first create an object of the
appropriate type, and then select the grab command (keyboard shortcut
ctrl+G). For most objects this will bring up a file selector for you to
select the file to read, but for graphic objects (bitmaps, RLE sprites,
compiled sprites, and palettes) it will grab from the current contents of
the image buffer, so you must previously have read a picture into this
buffer with the File/Read Bitmap command (keyboard shortcut ctrl+G). You can
use the mouse or arrow keys to select which portion of the image to grab.
With the mouse, select the top left corner, click and hold the left mouse
button, and move to the bottom right corner before releasing the button.
Press the right mouse button to cancel. With the keyboard, use the arrow
keys to select the top left corner, press Space or Enter, adjust the size
with the arrow keys, and press Space or Enter again. By default the position
will snap to a 16x16 grid, which can be adjusted by changing the values in
the X-grid and Y-grid fields. Alternatively you can use the Box Grab
command, in which case you should draw a bounding box in color #255 around
your sprites, and can then just click once inside a box to grab the contents.

Note that palette data is not stored along with bitmap and sprite objects.
To store the entire contents of a PCX or BMP file, you will need to create
both bitmap and palette objects, and grab data into both of them. When you
reload the datafile the bitmap will probably be displayed with the wrong
palette. This can be corrected by double-clicking on the palette object,
which will select its contents as the current palette, meaning that it will
be used when displaying and exporting bitmaps.

The properties of the selected object are listed in the box to the right of
the item list. These can be edited by double-clicking on one of the
properties, and deleted by selecting one and pressing Del. You can insert
new properties by pressing Insert while the property list has the input
focus, or using the Object/Set Property command. Object names are stored as
NAME properties, so the rename command is simply a shortcut for editing this
property.

To simplify the process of grabbing several related images from a single
bitmap (for example a set of frames which form an animation), you can use
the File/Grab from Grid command. Like the normal bitmap grab command, this
uses data from the image buffer, so you must read in a bitmap before you use
it. You will then be able to adjust the grabbing parameters, enter a name
for the new objects, and choose the type of object to create (bitmap, RLE
sprite, or compiled sprite). Because several objects may be created, their
names will be formed by adding a number to the end of the name you supply,
for example if you enter "a_picture", the grabber will create the objects
"a_picture000", "a_picture001", etc. There are two grabbing modes: using
cutouts of color 255, and using a regular grid. The regular grid option
simply divides the bitmap up into a set of equally sized tiles, using the
specified grid size, and grabs each of these as a separate object. If you
set the Skip Empties flag, the grabber will ignore tiles that don't contain
any data (ie. those that are a single solid color). The color 255 option is
more flexible. It expects the bitmap to contain information describing the
position and size of each tile, in the form of a bounding box drawn in color
255. The most reliable way to do this is to fill all the image except the
parts you want with color 255, but the grabber should be able to understand
more complicated layouts, even if you simply draw color 255 lines along the
top and left edges of the area you want to be grabbed. For truecolor images
where color 255 is not particularly meaningful, use a cyan bounding box
(maximum blue and green, zero red), with a single yellow (maximum red and
green, zero blue) pixel in the top left corner of the box.

By default, the grabber will run in a 640x480 resolution, using the highest
color depth possible on your graphics card. If you want to override this,
you can specify an alternative color depth or resolution on the commandline,
eg. "grabber -8" for a 256 color mode, "grabber -16" for 16 bit hicolor
graphics, "grabber -320x200" to use VGA mode 13h, or "grabber 1024x768".
Warning: editing datafiles that contain truecolor graphics is very slow in
256 color video modes, and the grabber is not really usable in resolutions
lower than 640x400.

You can configure the grabber to use external tools for editing data, by
setting some variables in the [grabber] section of the allegro.cfg file.
These are in the form "type=command", where the type is a four letter object
ID, and the command is whatever program you want to be invoked to edit this
kind of data. For these variables to be seen, the allegro.cfg file must
either be in the same directory as the grabber executable, or in the
directory pointed to by your ALLEGRO environment variable. To invoke this
feature, select the Shell Edit command or press ctrl+Z. The grabber will try
to invoke the tool on the original version of the file if it knows where you
grabbed the data from in the first place, or otherwise it will write the
object out into a temporary file prior to editing.



==================================
======== The DAT archiver ========
==================================


As an alternative to the graphical grabber program, you can use the command
line dat utility. This accepts the following options:

'-a <files>'
Adds the named files to the datafile, for example:

dat myfile.dat -a title.pcx scream.wav

If the objects are already present in the datafile, their current
contents will be replaced. Names for the new objects will be generated
from the input filenames, and the object type will be detected from
the file extensions. In some cases this is ambiguous, for example a
PCX file can be read as a bitmap, RLE sprite, compiled sprite, or font
object, so you may need to explicitly specify the object type with the
'-t' flag. For example, to insert alien.pcx as an RLE sprite, use the
command:

dat myfile.dat -a alien.pcx -t RLE

'-bpp colordepth'
Specifies which color format bitmap data should be grabbed in (valid
depths are 8, 15, 16, 24, and 32 bits per pixel).

'-c0' - no compression
'-c1' - compress objects individually
'-c2' - global compression on the entire datafile
Sets the compression mode (see below). These can be used on their own
to convert a datafile from one format to another, or in combination
with any other options.

'-d <objects>'
Deletes the named objects from the datafile.

'-dither'
Dithers graphics when reducing color depths.

'-e <objects>'
Extracts the named objects from the datafile. To extract everything,
use the wildcard * as the object name. To set the output filename or
directory, use the '-o filename' option. For example, to extract an
object called TITLE_SCREEN to the file title.pcx, use the command:

dat myfile.dat -e title_screen -o title.pcx

To extract the entire contents of the datafile to the directory
c:\output, use:

dat myfile.dat -e * -o c:\output\

'-g x y w h'
Grabs bitmap data from a specific grid location.

'-h outputfile.h'
Sets the output header file, for exporting object index definitions.
This may be used on its own to produce a header file from an existing
datafile, or in combination with any other commands. You can also use
the '-p prefixstring' option to set a prefix string for the object
definitions.

'-k'
Keep original names while grabbing objects. Without this switch, a
file called image.pcx will be imported as an object called IMAGE_PCX,
to ensure that all the object names are valid symbols for the output
header defines.

'-l'
Lists the contents of the datafile. This can be combined with the '-v'
option to list object properties along with the names, and you can
specify particular objects to produce a partial listing.

'-m dependencyfile'
Writes a set of makefile dependencies into the specified file, which
can be used to automatically update the file whenever any of the
source data changes.

'-o output'
Sets the output file or directory when extracting data.

'-p prefixstring'
Sets the prefix for the output header file.

'-pal objectname'
Specifies which palette to use.

'-s0' - no strip: save everything
'-s1' - strip grabber specific information from the file
'-s2' - strip all object properties and names from the file
Sets the strip mode (see below). These can be used on their own to
strip properties from the datafile, or in combination with any other
options.

'-t type'
Sets the object type when adding files.

'-transparency'
Preserves transparency when converting between color depths.

'-u'
Updates the contents of the datafile. See below.

'-v'
Selects verbose mode. This can be used in combination with any other
options to produce more detailed output.

'-w'
Always updates the entire contents of the datafile.

'-007 password'
Sets the file encryption key.

'<objects> PROP=value'
Sets properties for the specified objects. This works like environment
variables, in that setting a property to an empty string removes it.
Because object names are stored as NAME properties, you can use this
command to rename objects. For example, to rename MY_OBJECT to
WHAT_A_SILLY_NAME, use the command:

dat myfile.dat my_object NAME=what_a_silly_name

You can use the wildcard * to apply the property to everything in the
file, so to remove the ORIG property from the entire datafile, you
could execute:

dat myfile.dat * ORIG=

You can create hierarchical nested datafiles by inserting one datafile into
another with the '-a' command. Objects in the nested datafile can then be
referred to by as "parentname/objectname". For example if the datafile
myfile.dat contains a nested datafile called nestedfile, which contains a
bitmap called thepicture, you could export the bitmap with the command:

dat myfile.dat -e nestedfile/thepicture -o output.pcx



==================================
======== Misc Information ========
==================================


Datafiles can be saved using any of three compression types, selected from
the list at the top right of the grabber screen, or with the '-c0', '-c1',
and '-c2' options to dat. With type 0, the data is not compressed at all.
Type 1 compresses each object individually, while type 2 uses global
compression over the entire file. As a rule, global compression will give
better results than per-object compression, but it should not be used if you
intend to dynamically load specific objects with the load_datafile_object()
function or "filename.dat#objectname" packfile syntax.

There are also three strip modes for saving datafiles, selected with the
File/Save Stripped command in the grabber, or using the '-s0', '-s1', and
'-s2' options to dat. With zero stripping, all object properties are written
to the datafile, which is normally what you will want. With strip mode 1,
properties specific to the grabber (the ones describing the origins and
dates of each object) are removed, which will marginally reduce the file
size, but will prevent the update command from working. For the smallest
possible file sizes, strip mode 2 removes all properties, including object
names and any custom properties you have added. This level of stripping
should obviously be used with extreme caution, although in some cases it may
be possible to recover the object names even after they have been stripped
out of the datafile. If the grabber and dat utilities cannot find any name
properties in a datafile, they will look for a header (.h) file with the
same name, and attempt to parse this to recover the names. This is far from
foolproof, and will not work for nested datafiles, but in some situations it
allows the names to be read back from the index definition header.

Both the grabber and the dat utility have an update command, which scans
through the datafile checking if any objects have changed, and replacing
those which are out of date. This depends on the origin and date properties
which were set when the data was grabbed in the first place, so it won't
work if these properties have been stripped out of the file. This command
can be very useful if you build a datafile containing hundreds of objects
grabbed from external bitmaps, and later go back and change some of these
bitmaps. Rather than having to figure out which objects are out of date and
then manually re-grab all the affected data, the update command will
automatically refresh the modified objects.

Fonts can be read from GRX format .fnt files, 8x8 or 8x16 BIOS format .fnt
files, and from bitmap images, or you can import a multiple-range Unicode
font by writing a .txt script that specifies a number of different source
files for each range of characters. The script file contains a number of
lines in the format "filename start end", which specify the source file for
that range of characters, the Unicode value of the first character in the
range, and the end character in the range (optional, if left out, the entire
input file will be grabbed). If the filename is replaced by a hyphen, more
characters will be grabbed from the previous input file. For example, the
script:

ascii.fnt 0x20 0x7F
- 0xA0 0xFF
dingbats.fnt 0x1000

would import the first 96 characters from ascii.fnt as the range 0x20-0x7F,
the next 96 characters from ascii.fnt as the range 0xA0-0xFF, and the entire
contents of dingbats.fnt starting at Unicode position 0x1000.

When reading a font from a bitmap file the size of each character is
determined by the layout of the image, which should be a rectangular grid
containing all the ASCII characters from space (32) up to the tilde (126).
The spaces between each letter should be filled with color 255. If each
character is sized exactly 8x8 or 8x16 the grabber will create a fixed size
font, otherwise it will make a proportional font. Probably the easiest way
to get to grips with how this works is to load up the demo.dat file and
export the TITLE_FONT into a PCX file. Have a look at the resulting picture
in your paint program: that is the format a font should be in...

Bitmap and RLE sprites can store an alpha channel along with the color
information, as long as they are in a 32 bit format. Alpha data can be read
directly from 32 bit TGA files, or you can use the alpha channel commands
(in the Object menu, or the right mouse button popup menu) to import a
greyscale alpha image over the top of an existing object. This menu also
contains options for viewing the alpha channel of the selected object,
exporting the alpha data to a greyscale image file, and deleting the alpha
data to leave only pure color information. You can also use the File menu to
import an alpha channel over the top of a bitmap that you have loaded with
the Read Bitmap command, after which the alpha information will be included
when you next perform a Grab or Grab From Grid operation.

Datafiles can be encrypted with a password, by typing it into the
"Password:" field in the grabber, or using the '-007 password' option to the
dat utility. Passwords may be up to 256 characters in length, and are case
sensitive. Encrypted files _cannot_ be read without the password, so please
don't forget it and then come crying to me for help :-) To read an encrypted
file into your program, call the packfile_password() function before
load_datafile(). It is also a good idea to call packfile_password(NULL)
afterwards, to set everything back to normal.

Melonhead
02-22-2004, 03:41 PM
=====================================
======== Accessing Datafiles ========
=====================================


In order to access the contents of a datafile, you will need to know where
each object is located. The easiest way to do this is by integer index,
using an automatically generated header file. With the grabber, type a name
into the "Header:" field, and the object indexes will be written to this
file whenever the datafile is saved. With the dat utility, use the '-h'
option, eg. "dat filename.dat -h filename.h". The header will define C
preprocessor symbols for each object in the datafile, for example:

#define SOME_DATA 0 /* DATA */
#define SOME_MORE_DATA 1 /* DATA */

To prevent name conflicts, you can specify a prefix string for these
definitions by typing it into the "Prefix:" field in the grabber or using
the '-p' option to dat.

To load a datafile into memory, call the function:

DATAFILE *load_datafile(char *filename);

This will load the entire file, returning a pointer to it, or NULL on error.
When the data is no longer required, the entire thing can be destroyed by
calling:

void unload_datafile(DATAFILE *dat);

When you load a datafile, you will obtain a pointer to an array of DATAFILE
structures:

typedef struct DATAFILE
{
void *dat; - pointer to the actual data
int type; - object type ID
long size; - size of the data, in bytes
DATAFILE_PROPERTY *prop; - list of object properties
} DATAFILE;

The only really important piece of information here is the dat field, which
points to the contents of the object. What type of data this is will depend
on the type of object: for bitmaps it will be an Allegro BITMAP structure,
for RLE sprites an RLE_SPRITE, for fonts a FONT structure, etc. If you are
programming in C you can pass this pointer directly to the relevant Allegro
library functions, but if you are using C++ you will need to cast it to the
appropriate type to prevent the compiler giving a warning.

For example, if you have a datafile called myfile.dat, which contains a
bitmap called COOL_PICTURE, and you have used it to produce a header called
myfile.h, you could display the bitmap with the code:

#include "myfile.h"

void show_the_bitmap()
{
DATAFILE *dat;
BITMAP *bmp;

dat = load_datafile("myfile.dat");
if (!dat) {
/* report an error! */
return;
}

bmp = (BITMAP *)dat[COOL_PICTURE].dat;
blit(bmp, screen, 0, 0, 0, 0, bmp->w, bmp->h);
unload_datafile(dat);
}

If a datafile contains nested child datafiles, the header will prefix the
names of objects in the sub-files with the name of their parent datafile. It
will also define a count of the number of objects in the child file, which
may be useful if for example the child datafile contains several bitmaps
which form a 'run' animation, and you want your code to automatically
adjust to the number of frames in the datafile.

For example, the datafile:

"FILE" - NESTED_FILE
|- "BMP" - A_BITMAP
|- "FONT" - A_FONT
"DATA" - SOME_DATA
"DATA" - SOME_MORE_DATA

produces the header:

#define NESTED_FILE 0 /* FILE */

#define NESTED_FILE_A_BITMAP 0 /* BMP */
#define NESTED_FILE_A_FONT 1 /* FONT */
#define NESTED_FILE_COUNT 2

#define SOME_DATA 1 /* DATA */
#define SOME_MORE_DATA 2 /* DATA */

The main datafile contains three objects (NESTED_FILE, SOME_DATA, and
SOME_MORE_DATA) with consecutive indexes, while the child datafile contains
the two objects A_BITMAP and A_FONT. To access these objects you need to
reference both the parent and child datafiles, eg:

DATAFILE *dat = load_datafile("whatever.dat");
DATAFILE *nested = (DATAFILE *)dat[NESTED_FILE].dat;
FONT *thefont = (FONT *)nested[NESTED_FILE_A_FONT].dat;

If you need to access object property strings from within your program, you
can use the function:

char *get_datafile_property(DATAFILE *dat, int type);

This will return a pointer to the property string if it can be found, and an
empty string (not null!) if it does not exist. One possible use of this
function is to locate objects by name, rather than using the indexes from a
header file. The datafile array is ended by an object of type DAT_END, so to
search the datafile dat for the object "my_object" you could use the code:

for (i=0; dat[i].type != DAT_END; i++) {
if (stricmp(get_datafile_property(dat+i, DAT_ID('N','A','M','E')),
"my_object") == 0) {
/* found the object at index i */
}
}
/* not found... */

If you prefer to access objects by name rather than index number, you can
use the function:

DATAFILE *find_datafile_object(DATAFILE *dat, char *objectname);

This will search an already loaded datafile for an object with the specified
name, returning a pointer to it, or NULL if the object cannot be found. It
understands '/' and '#' separators for nested datafile paths.

It is also possible to selectively load individual objects from a datafile,
with the function:

DATAFILE *load_datafile_object(char *filename, char *objectname);

This searches the datafile for an object with the specified name, so
obviously it won't work if you strip the name properties out of the file.
Because this function needs to seek through the data, it will be extremely
slow if you have saved the file with global compression. If you are planning
to load objects individually, you should save the file uncompressed or with
individual compression per-object. Because the returned datafile points to a
single object rather than an array of objects, you should access it with the
syntax datafile->dat, rather than datafile[index].dat, and when you are done
you should free the object with the function:

void unload_datafile_object(DATAFILE *dat);

Alternatively, the packfile functions can open and read directly from the
contents of a datafile object. You do this by calling pack_fopen() with a
fake filename in the form "filename.dat#object_name". The contents of the
object can then be read in an identical way to a normal disk file, so any of
the file access functions in Allegro (eg. load_pcx() and set_config_file())
can be used to read from datafile objects. Note that you can't write to
datafiles in this way: the fake file is read only. Also, you should save the
file uncompressed or with per-object compression if you are planning on
using this feature. Finally, be aware that the special Allegro object types
aren't the same format as the files you import the data from, so if for
example you want to use load_pcx to read an image from a datafile, you
should import it as a binary data chunk rather than as a BITMAP object.

If you have appended a datafile to the end of your executable with the
exedat utility, use load_datafile("#") to read the entire thing into memory,
load_datafile_object("#", "object_name") to load a specific object, and
pack_fopen("#object_name", F_READ) to read one of the objects directly with
your own code.

By default, all graphic objects loaded from a datafile will be converted
into the current color depth. This conversion may be both lossy and very
slow, particularly when reducing from truecolor to 256 color formats, so you
may wish to disable it by calling set_color_conversion(COLORCONV_NONE) or
set_color_conversion(COLORCONV_PARTIAL) before your call to load_datafile().



=====================================
======== Compiling Datafiles ========
=====================================


The utility dat2s can be used to convert a datafile into an asm (.s) source
file, which can then be assembled and linked into your program. This avoids
the need for a separate datafile to accompany your program, and means the
data will automatically be loaded into memory at startup. You should be
aware, though, that large datafiles can take a long time to compile, and
that it is not possible to compress data which is compiled in this way.

The simplest way to invoke dat2s is with the command:

dat2s filename.dat -o output.s

The resulting asm file can then be assembled with the command:

gcc -c output.s

This will produce an object module called output.o, which can be linked into
your program, for example:

gcc myprog.c -o myprog.exe output.o -lalleg

Your program can then access the contents of the datafile as simple global
variables. Definitions for these variables can be obtained by telling dat2s
to output a header file as well as the asm file, with the '-h' option. You
can also use '-p' to set a prefix string for all the object names. For
example, when applied to the datafile:

"BMP" - A_BITMAP
"BMP" - ANOTHER_BITMAP
"SAMP" - EXPLODE
"PAL" - SOME_COLORS
"FONT" - THE_FONT

the command:

dat2s filename.dat -o output.s -h output.h -p item

produces the header:

extern BITMAP item_a_bitmap;
extern BITMAP item_another_bitmap;
extern SAMPLE item_explode;
extern PALETTE item_some_colors;
extern FONT item_the_font;
extern DATAFILE item_data[];

You can refer to these objects directly, for example:

blit(&item_a_bitmap, screen, 0, 0, 0, 0, SCREEN_W, SCREEN_H);

Alternatively, you can use the datafile array for compatibility with code
that was originally written for separately loaded datafiles, with the
standard syntax item_data[index].dat.



================================
======== Custom Objects ========
================================


Some of the objects in a datafile, for example palettes and FLI animations,
are simply treated as blocks of binary data, but others are loaded into
special formats such as bitmap structures or compiled sprites. It is
possible to extend the datafile system to support your own custom object
types, eg. map objects for a tile based engine, or level data for a platform
game. Obviously the grabber has no way of understanding this data, but it
will allow you to import binary data from external files, so you can grab
information produced by your own utilities. If you are happy with the data
being loaded as a simple binary block, that is all you need to do, but if
you need to load it into a specific structure, read on...

Your custom objects must be given a unique type ID, which is formed from
four ASCII characters (by convention all uppercase A-Z). If you don't use
all four characters, the string should be padded with spaces (ASCII 32). You
should use this ID when creating the objects in the grabber (select
New/Other and type in the ID string), and in your code you should define an
identifier for the type, eg:

#define DAT_MAPDATA DAT_ID('M','A','P','D')

You then need to write functions for loading and destroying objects of this
type, in the form:

void *load_mapdata(PACKFILE *f, long size)
{
/* Allegro will call this function whenever an object of your custom
* type needs to be loaded from a datafile. It will be passed a
* pointer to the file from which the data is to be read, and the size
* of the object in bytes. It should return a pointer to the loaded
* data, which will be stored in the dat field of the datafile object
* structure, or NULL if an error occurs. The file will have been
* opened as a sub-chunk of the main datafile, so it is safe to read
* past the end of the object (if you attempt this, Allegro will
* return EOF), and it is also safe to return before reading all the
* data in the chunk (if you do this, Allegro will skip any unused
* bytes before starting to read the next object). You should _not_
* close the file when you are done: this will be handled by the
* calling function. To clarify how all this works, here's an example
* implementation of a null-terminated string object:
*/

#define MAX_LEN 256

char buf[MAX_LEN];
char *p;
int c;

for (c=0; (c<MAX_LEN-1) && (!pack_feof(f)); c++)
buf[c] = pack_getc(f);

buf[c] = 0;

p = malloc(c+1);
strcpy(p, buf);

return p;
}

void destroy_mapdata(void *data)
{
/* Allegro will call this function whenever an object of your custom
* type needs to be destroyed. It will be passed a pointer to the
* object (as returned by the load function), and should free whatever
* memory the object is using. For example, the simple string object
* returned by the above loader could be destroyed with the code:
*/

if (data)
free(data);
}

Finally, before you load your datafile you must tell Allegro about the
custom format, by calling:

register_datafile_object(DAT_MAPDATA, load_mapdata, destroy_mapdata);

It is also possible to integrate support for custom object types directly
into the grabber and dat utilities, by copying some special files into the
tools/plugins directory. This can be used to add whole new object types and
menu commands, or to provide additional import/export routines for the
existing formats. See tools/plugins/plugins.txt for an overview of how to
write your own grabber plugins.



=================================
======== The File Format ========
=================================


In case anyone wants to do some serious hackery, and for my own future
reference, here are some details of the innards of the datafile format.

Note that this is different to the datafile format used by Allegro versions
2.1 and earlier. Allegro can still load files from the old format, but it
was much less flexible and didn't support nice things like object
properties, so you should load any old files into the grabber and save them
out again to convert to the new format.

Nb. if all you want to do is write a utility that manipulates datafiles in
some way, the easiest approach is probably to use the helper functions in
datedit.c, which are currently shared by the dat, dat2s, and grabber
programs. These functions handle loading, saving, inserting and deleting
objects, and modifying the contents of datafiles in various ways, but life
is too short for me to bother documenting them all here. Look at the
source...

Anyway. All numbers are stored in big-endian (Motorola) format. All text is
stored in UTF-8 encoding. A datafile begins with one of the 32 bit values
F_PACK_MAGIC or F_NOPACK_MAGIC, which are defined in allegro.h. If it starts
with F_PACK_MAGIC the rest of the file is compressed with the LZSS
algorithm, otherwise it is uncompressed. This magic number and optional
decompression can be handled automatically by using the packfile functions
and opening the file in F_READ_PACKED mode. After this comes the 32 bit
value DAT_MAGIC, followed by the number of objects in the root datafile (not
including objects nested inside child datafiles), followed by each of those
objects in turn.

Each object is in the format:

OBJECT =
var - <property list> - any properties relating to the object
32 bit - <type ID> - object type ID
32 bit - <compressed size> - size of the raw data in the file
32 bit - <uncompressed size> - see below
var - <data> - the contents of the object

The property list can contain zero or more object properties, in the form:

PROPERTY =
32 bit - <magic> - "prop"
32 bit - <type ID> - property type ID
32 bit - <size> - size of the property string, in bytes
var - <data> - property string, _not_ null-terminated

If the uncompressed size field in an object is positive, the contents of the
object are not compressed (ie. the raw and compressed sizes should be the
same). If the uncompressed size is negative, the object is LZSS compressed,
and will expand into -<uncompressed size> bytes of data. The easiest way to
handle this is to use the pack_fopen_chunk() function to read both the raw
and compressed sizes and the contents of the object.

The contents of an object vary depending on the type. Allegro defines the
standard types:

DAT_FILE =
32 bit - <object count> - number of objects in the sub-file
var - <object list> - objects in the same format as above

DAT_FONT =
16 bit - <font size> - 8, 16, -1, or 0

if font size == 8 { - obsolete as of version 3.9.x!
unsigned char[95][8] - 8x8 bit-packed font data
}

if font size == 16 { - obsolete as of version 3.9.x!
unsigned char[95][16] - 8x16 bit-packed font data
}

if font size == -1 { - obsolete as of version 3.9.x!
95x {
16 bit - <width> - character width
16 bit - <height> - character height
var - <data> - character data (8 bit pixels)
}
}

if font size == 0 { - new format introduced in version 3.9.x
16 bit - <ranges> - number of character ranges
for each range {
8 bit - <mono> - 1 or 8 bit format flag
32 bit - <start> - first character in range
32 bit - <end> - last character in range (inclusive)
for each character {
16 bit - <width> - character width
16 bit - <height> - character height
var - <data> - character data
}
}
}

DAT_SAMP =
16 bit - <bits> - sample bits (negative for stereo)
16 bit - <freq> - sample frequency
32 bit - <length> - sample length
var - <data> - sample data

DAT_MIDI =
16 bit - <divisions> - MIDI beat divisions
32x {
32 bit - <length> - track length, in bytes
var - <data> - MIDI track data
}

DAT_FLI =
var - <data> - FLI or FLC animation, standard format

DAT_BITMAP =
DAT_C_SPRITE =
DAT_XC_SPRITE =
16 bit - <bits> - bitmap color depth
16 bit - <width> - bitmap width
16 bit - <height> - bitmap height
var - <data> - bitmap data

Valid color depths are 8, 15, 16, 24, 32, and -32. Both 15 and 16 bit
images are stored in 5.6.5 RGB format, and 24 and 32 bit images as
8.8.8 RGB. The special -32 flag indicates that the data is in true 32
bit RGBA format.

DAT_RLE_SPRITE =
16 bit - <bits> - sprite color depth
16 bit - <width> - sprite width
16 bit - <height> - sprite height
32 bit - <size> - data size, in bytes
var - <data> - RLE compressed sprite data

Valid color depths are 8, 15, 16, 24, 32. and -32. Both 15 and 16 bit
images are stored in 5.6.5 RGB format with 16 bit skip counts and EOL
markers, and 24 and 32 bit images as 8.8.8 RGB. with 32 bit skip
counts and markers. The special -32 flag indicates that the data is in
true 32 bit RGBA format.

DAT_PALETTE =
256 x {
8 bit - <red> - red component, 0-63
8 bit - <green> - green component, 0-63
8 bit - <blue> - blue component, 0-63
8 bit - <pad> - alignment padding
}

I think that covers everything.

I don't think you needed all of that, most is just for developers, but oh well.

Freedom
02-22-2004, 04:04 PM
yea, I had it figured out and replaced the msg and refill sounds in my sfx file already.
but info is always welcome at any rate :)
thanks :)