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Clarify and update rgbgfx documentation

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Signed-off-by: obskyr <powpowd@gmail.com>
This commit is contained in:
obskyr
2018-02-15 15:05:52 +01:00
parent b8af100c63
commit 898f75ce57
2 changed files with 67 additions and 23 deletions
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src/gfx/rgbgfx.1
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@@ -24,7 +24,28 @@
The
.Nm
program converts PNG images into the Nintendo Game Boy's planar tile format.
The arguments are as follows:
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 D
Debug features are enabled.
@@ -33,24 +54,25 @@ Fix the input PNG file to be a correctly indexed image.
.It Fl F
Same as
.Fl f ,
but additionally, the input PNG file is fixed to have its parameters match the
command line's parameters.
but additionally, the supplied command line parameters are saved within the PNG
and will be loaded and automatically used next time.
.It Fl d Ar depth
The bitdepth of the output image (either 1 or 2).
By default, the bitdepth is 2 (two bits per pixel).
The bit depth of the output image (either 1 or 2).
By default, the bit depth is 2 (two bits per pixel).
.It Fl h
Lay out tiles horizontally rather than vertically.
.It Fl o Ar outfile
The name of the output file.
.It Fl p Ar palfile
Raw bytes (8 bytes for two bits per pixel, 4 bytes for one bit per pixel)
containing the RGB15 values in the little-endian byte order and then ordered
from lightest to darkest.
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 pallete file output name is made by taking the input filename,
removing the file extension, and appending
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 mapfile
If any tiles are the same, don't place the repeat tiles in the output file, and
@@ -73,7 +95,7 @@ the PNG file don't match.
Trim the end of the output file by this many tiles.
.El
.Sh EXAMPLES
The following will take a PNG file with a bitdepth of 1, 2, or 8, and output
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