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.\"
.\" This file is part of RGBDS.
.\"
.\" Copyright (c) 2013-2018, stag019 and RGBDS contributors.
.\"
.\" SPDX-License-Identifier: MIT
.\"
.Dd January 26, 2018
.Dt RGBGFX 1
.Os RGBDS Manual
.Sh NAME
.Nm rgbgfx
.Nd Game Boy graphics converter
.Sh SYNOPSIS
.Nm rgbgfx
.Op Fl ACDfFhmPTuVv
.Op Fl o Ar outfile
.Op Fl a Ar attrmap
.Op Fl d Ar depth
.Op Fl p Ar palfile
.Op Fl t Ar tilemap
.Op Fl x Ar tiles
.Ar file
.Sh DESCRIPTION
The
.Nm
program converts PNG images into the Nintendo Game Boy's planar tile format.

The resulting colors and their palette indices are determined differently
depending on the input PNG file:
.Bl -dash -width Ds
.It
If the file has an embedded palette, that palette's color and order are used.
.It
If not, and the image only contains shades of gray, rgbgfx maps them to the
indices appropriate for each shade. Any undetermined indices are set to
respective default shades of gray. For example: if the bit depth is 2 and the
image contains light gray and black, they become the second and fourth colors -
and the first and third colors get set to default white and dark gray. If the
image has multiple shades that map to the same index, the palette is instead
determined as if the image had color.
.It
If the image has color (or the grayscale method failed), the colors are sorted
from lightest to darkest.
.El

The input image may not contain more colors than the selected bit depth
allows. Transparent pixels are set to palette index 0.
.Sh ARGUMENTS
.Bl -tag -width Ds
.It Fl a Ar attrmap
Generate a file of tile mirroring attributes for OAM or (CGB-only) background
tiles. For each tile in the input file, a byte is written representing the
dimensions that the associated tile in the output file should be mirrored.
Useful in combination with
.Fl m
to keep track the mirror direction of mirrored duplicate tiles.
.It Fl A
Same as
.Fl a ,
but the attrmap file output name is made by taking the input filename, removing
the file extension, and appending
.Pa .attrmap .
.It Fl C
Use the color curve of the Game Boy Color when generating palettes.
.It Fl D
Debug features are enabled.
.It Fl d Ar depth
The bit depth of the output image (either 1 or 2).
By default, the bit depth is 2 (two bits per pixel).
.It Fl f
Fix the input PNG file to be a correctly indexed image.
.It Fl F
Same as
.Fl f ,
but additionally, the supplied command line parameters are saved within the PNG
and will be loaded and automatically used next time.
.It Fl h
Lay out tiles horizontally rather than vertically.
.It Fl m
Truncate tiles by checking for tiles that are mirrored versions of others and
omitting these from the output file. Useful with tilemaps and attrmaps together
to keep track of the duplicated tiles and the dimension mirrored. Tiles are
checked for horizontal, vertical, and horizontal-vertical mirroring. Implies
.Fl u .
.It Fl o Ar outfile
The name of the output file.
.It Fl p Ar palfile
Output the image's palette in standard GBC palette format - bytes (8 bytes for
two bits per pixel, 4 bytes for one bit per pixel) containing the RGB15 values
in little-endian byte order. If the palette contains too few colors, the
remaining entries are set to black.
.It Fl P
Same as
.Fl p ,
but the palette file output name is made by taking the input PNG file's
filename, removing the file extension, and appending
.Pa .pal .
.It Fl t Ar tilemap
Generate a file of tile indices. For each tile in the input file, a byte is
written representing the index of the associated tile in the output file.
Useful in combination with
.Fl u
or
.Fl m
to keep track of duplicate tiles.
.It Fl T
Same as
.Fl t ,
but the tilemap file output name is made by taking the input filename, removing
the file extension, and appending
.Pa .tilemap .
.It Fl u
Truncate tiles by checking for tiles that are exact duplicates of others and
omitting these from the output file. Useful with tilemaps to keep track of the
duplicated tiles.
.It Fl V
Print the version of the program and exit.
.It Fl v
Verbose.
Print errors when the command line parameters and the parameters in
the PNG file don't match.
.It Fl x Ar tiles
Trim the end of the output file by this many tiles.
.El
.Sh EXAMPLES
The following will take a PNG file with a bit depth of 1, 2, or 8, and output
planar 2bpp data:
.Pp
.D1 $ rgbgfx -o out.2bpp in.png
.Pp
The following creates a planar 2bpp file with only unique tiles, and its tilemap
.Pa out.tilemap :
.Pp
.D1 $ rgbgfx -T -u -o out.2bpp in.png
.Pp
The following creates a planar 2bpp file with only unique tiles (accounting for
tile mirroring) and its associated tilemap
.Pa out.tilemap
and attrmap
.Pa out.attrmap :
.Pp
.D1 $ rgbgfx -A -T -m -o out.2bpp in.png
.Pp
The following will do nothing:
.Pp
.D1 $ rgbgfx in.png
.Sh SEE ALSO
.Xr rgbds 7 ,
.Xr rgbasm 1 ,
.Xr rgblink 1 ,
.Xr rgbfix 1 ,
.Xr gbz80 7
.Sh HISTORY
.Nm
was created by
.An stag019
to be included in RGBDS.
It is now maintained by a number of contributors at
.Lk https://github.com/rednex/rgbds .