#!/bin/sh
#
#  mkanaglyph
#  Create a red-blue stereo anaglyph image from left & right images in PPM format.
#  Requires utilities distributed with netpbm.
#
#  Copyright 2004 Ken Hardy
#
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program 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 GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 675 Mass
# Ave, Cambridge, MA 02139, USA. 
#
# Never work with the only copy of your images files -- make a copy!
# More error and sanity checking is needed in the code below.
#


set - `getopt r:l:o:x: $@`
while [ $# -gt 0 ] ; do
  case "$1" in
	"-x")	let shiftby="$2"/2 ; shift; shift;
		;;
	"-r")	rightjpg="$2" ; shift;shift;
		;;
	"-l")	leftjpg="$2" ; shift;shift;
		;;
	"-o")	output="$2" ; shift;shift;
		;;

	"--")   shift ;
		break 2 ;
	 	;;
	default)	echo "bad options." >&2 ;
			exit 1 ;
			;;
  esac
done


[ "$output"x != x -a "$rightjpg"x != x -a "$leftjpg"x != x ] || {
	echo "Usage: $0 [-x offset] -l left.jpg -r right.jpg -o output.jpg" >&2 ;
	echo >&2 ;
             #........................................................................
	echo "   Offset, if required, is number of pixels to shift the images" >&2 ;
	echo "   hoziontally for comfortable viewing." >&2 ;
	echo >&2 ;
	echo "   Always work with a copy of your image files!" >&2 ;
	echo >&2 ;
	exit 1 ;
}

left=`basename \`basename $leftjpg .jpg\` .JPG`
right=`basename \`basename $right .jpg\` .JPG`

[ -f ${left}.ppm ] && { echo ${left}.ppm already exists >&2 ; exit 1 ; }
[ -f ${right}.ppm ] && { echo ${left}.ppm already exists >&2 ; exit 1 ; }

tmpppm=_tmpppm_$$

trap "/bin/rm -f ${left}.ppm ${left}.red ${left}.grn ${left}.blu ${right}.ppm ${right}.red ${right}.grn ${right}.blu ${tmpppm}; exit" 0

jpegtopnm ${leftjpg} > ${left}.ppm 2>/dev/null
jpegtopnm ${rightjpg} > ${right}.ppm 2>/dev/null


# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[ "$shiftby"x = x ] || {
	unset width height ;
	eval `pnmfile ${left}.ppm | sed -n '/[0-9] by [0-9]/s/.*\ \([1-9][0-9]*\) by \([1-9][0-9]*\) .*/width=\1 height=\2/p'` ;
	[ "$width" ] || exit 1 ;
	let width=$width-$shiftby ;
	pnmcut ${right}.ppm -top 0 -left 0 -width $width -height $height > $tmpppm
	/bin/mv $tmpppm ${right}.ppm

	pnmcut ${left}.ppm -top 0 -left $shiftby -width $width -height $height > $tmpppm
	/bin/mv $tmpppm ${left}.ppm
}

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ppmtorgb3 ${left}.ppm && \
ppmtorgb3 ${right}.ppm && \
rgb3toppm ${left}.red ${right}.grn ${right}.blu | ppmtojpeg >$output

res=$?

rm -f ${left}.red ${left}.grn ${left}.blu
rm -f ${right}.red ${right}.grn ${right}.blu
rm -f ${tmpppm}

exit $res