#!/bin/bash
# 
# Developed by Fred Weinhaus 8/10/2008 .......... revised 11/29/2023
#
# ------------------------------------------------------------------------------
# 
# Licensing:
# 
# Copyright © Fred Weinhaus
# 
# My scripts are available free of charge for non-commercial use, ONLY.
# 
# For use of my scripts in commercial (for-profit) environments or 
# non-free applications, please contact me (Fred Weinhaus) for 
# licensing arrangements. My email address is fmw at alink dot net.
# 
# If you: 1) redistribute, 2) incorporate any of these scripts into other 
# free applications or 3) reprogram them in another scripting language, 
# then you must contact me for permission, especially if the result might 
# be used in a commercial or for-profit environment.
# 
# My scripts are also subject, in a subordinate manner, to the ImageMagick 
# license, which can be found at: http://www.imagemagick.org/script/license.php
# 
# ------------------------------------------------------------------------------
# 
####
#
# USAGE: pano2rect [-v vtop,vbot] [-p pfov] [-f format] [-i iyc] [-o oyc] [-h height] [-vp vpmethod] [-b bgcolor] infile outfile
# USAGE: pano2rect [-help]
# 
# OPTIONS:
# 
# -v      vtop,vbot         vertical viewing angles corresponding to the
#                           top and bottom of the panoramic image;
#                           default=-0,-90 (90 degree vertical 
#                           range of view, i.e. horizon to nadir)
# -p      pfov              perspective image vertical field of view in degrees;
#                           float; 0<pfov<180; default=vrange=(vtop-vbot)
# -f      format            output perspective format; tilt (T) 
#                           or level (L) (perspective); default=tilt
# -i      iyc               pixel coordinates of the desired row in the input 
#                           panoramic image that is to be the center of 
#                           the perspective correction; float; 
#                           default=center of panorama image
# -o      oyc               pixel coordinates of the desired row in the output 
#                           perspective image that is to be the center of 
#                           the perspective correction; float; 
#                           default=center of perspective image for format=tilt;
#                           default=bottom of perspective image for format=level
# -h      height            desired height of output; 
#                           Default=same as input
# -vp     vpmethod          virtual-pixel method to use to fill area of output image 
#                           that are outside the input image; default=black
# -b      bgcolor           background color for virtual-pixel=background
#                           any valid IM color is allowed. The default=black
# 
###
# 
# NAME: PANO2RECT
# 
# PURPOSE: To apply vertical perspective correction to an angular panoramic image
# 
# DESCRIPTION: PANO2RECT applies vertical perspective correction to an angular 
# panoramic image. The output formats are either tilt or leve. These describe 
# only the vertical format for the output image. The horizontal format will not 
# be changed. For tilt format, the output will be a tilted view with the look 
# direction towards the mid row of the input panoramic image. For level format,  
# the perspective will be looking horizontally.
# 
# ARGUMENTS: 
# 
# -v vtop,vbot ... VTOP,VBOT are the vertical viewing angles at the top and 
# bottom of the input panorama image. The default is 90,0 which corresponds 
# to a 90 degree vertical range of view, i.e. zenith to horizon.
# 
# -p pfov ... PFOV is the vertical output perspective image field of view 
# in degrees. Values are floats in the range 0<pfov<180. The default is to 
# use the vertical viewing range of the fisheye image, which is vrange = 
# (vrad-vcen) = ifov/2 (half of the field of view across the circular diameter). 
# The amount of input image in the output perspective image will depend upon  
# the pfov parameter. Note that in comparison, a value of 27 degrees 
# corresponds to a vertical field of view from a 35 mm camera 
# (film size 36mm x 24mm) with a 50mm focal length lens, i.e. a "normal" 
#  view. 
# 
# -f format ... FORMAT is the output image perspective format. The choices are: 
# tilt (T) and level (L). The default is tilt. If tilt (T) is chosen, then the 
# output image will have perspective correction applied in the vertical direction 
# and the image will be centered by default about the mid-angle of the panorama 
# image, i.e., vertical center of the panorama. In other words a tilted vertical 
# perspective will be produced. If level (L) is chosen, then the output image will 
# also have perspective correction applied in the vertical direction. But the view 
# will be one that is not tilted, but looking horizontally. The horizon line will 
# default to the bottom of the output image (assuming that the top row of the 
# panorama image is looking above the horizon).
# 
# -i iyc ... IYC is the pixel coordinates in the input panorama image that will 
# be the center of the perspective correction. The default is the center row of the 
# panorama image. Values are non-negative floats.
# 
# -o oyc ... OYC is the pixel coordinates in the output perspective image that will 
# be the center of the perspective correction. The default is the center row of the 
# perspective image for format=tilt and the bottom row of the perspective image for 
# format=level (assuming that the top row of the panorama image is looking above 
# the horizon). Values are non-negative floats.
# 
# -h height ... HEIGHT is the desired height of the perspective image. The default 
# is the same as the input. Values larger than the input may be useful in showing 
# more of the image when a level perspective is used. Values other than the default 
# will not change the scale of the perspective image in the vertical dimension. They 
# will only allow more (or less) data to be viewed. 
# 
# -vp vpmethod ... VP is the virtual-pixel method. Any valid IM virtual-pixel 
# setting is allowed. The default is black.
# 
# -b bgcolor ... BGCOLOR is the background color to use with vpmethod=background. 
# Any valid IM color may be used. The default is black.
# 
# CAVEAT: No guarantee that this script will work on all platforms, 
# nor that trapping of inconsistent parameters is complete and 
# foolproof. Use At Your Own Risk. 
# 
######
# 

# set default values
vtop=90   				    # look direction in panorama at top of image
vbot=0   				    # look direction in panorama at bottom of image
pfov="" 					# perspective field of view (aperture) in degrees
iyc=""						# initialization of center perspective correction in panorama image
oyc=""						# initialization of center perspective correction in perspective image
format="tilt"				# tilt, level
vpmethod="black"			# virtual-pixel method
bgcolor="black"				# virtual-pixel background color
height=""					# extend vertical dimension of output perspective

# set directory for temporary files
dir="."    # suggestions are dir="." or dir="/tmp"

# set up functions to report Usage and Usage with Description
PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGDIR=`dirname $PROGNAME`            # extract directory of program
PROGNAME=`basename $PROGNAME`          # base name of program
usage1() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^###/g;  /^#/!q;  s/^#//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}
usage2() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^######/g;  /^#/!q;  s/^#*//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}


# function to report error messages
errMsg()
	{
	echo ""
	echo $1
	echo ""
	usage1
	exit 1
	}


# function to test for minus at start of value of second part of option 1 or 2
checkMinus()
	{
	test=`echo "$1" | grep -c '^-.*$'`   # returns 1 if match; 0 otherwise
    [ $test -eq 1 ] && errMsg "$errorMsg"
	}

# test for correct number of arguments and get values
if [ $# -eq 0 ]
	then
	# help information
   echo ""
   usage2
   exit 0
elif [ $# -gt 18 ]
	then
	errMsg "--- TOO MANY ARGUMENTS WERE PROVIDED ---"
else
	while [ $# -gt 0 ]
		do
			# get parameter values
			case "$1" in
		     -help)    # help information
					   echo ""
					   usage2
					   exit 0
					   ;;
				-v)    # get vtop,vbot
					   shift  # to get the next parameter
					   # no test if parameter starts with minus sign 
					   #errorMsg="--- INVALID VERTICAL ANGLE SPECIFICATIONS ---"
					   #checkMinus "$1"
					   test=`echo "$1" | tr "," " " | wc -w`
					   [ $test -ne 2 ] && errMsg "--- INCORRECT NUMBER OF VERTICAL ANGLE VALUES SUPPLIED ---"
					   vals=`expr "$1" : '\([-.0-9]*,[-.0-9]*\)'`
					   [ "$vals" = "" ] && errMsg "--- ANGLES=$vals MUST BE A PAIR OF FLOATS SEPARATED BY A COMMA ---"
		   			   vtop=`echo "$vals" | cut -d, -f1`
		   			   vbot=`echo "$vals" | cut -d, -f2`
		   			   ttest=`echo "$vtop < -180 || $vtop > 180" | bc`
		   			   btest=`echo "$vbot < -180 || $vbot > 180" | bc`
		   			   equaltest=`echo "$vtop == $vbot" | bc`
		   			   [ $ttest -eq 1 ] && errMsg "--- VTOP=$vtop MUST BE BETWEEN -180 AND 180 DEGREES ---"
		   			   [ $btest -eq 1 ] && errMsg "--- VBOT=$vbot MUST BE BETWEEN -180 AND 180 DEGREES ---"
		   			   [ $equaltest -eq 1 ] && errMsg "--- VTOP AND VBOT MAY NOT BE EQUAL ---"
					   ;;
				-f)    # get  format
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID FORMAT SPECIFICATION ---"
					   checkMinus "$1"
						case "$1" in
						 tilt)		format="tilt";;
						 T)			format="tilt";;
						 t)			format="tilt";;
						 level)		format="level";;
						 L)			format="level";;
						 l)			format="level";;
						esac
					   ;;
				-p)    # get pfov
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID PFOV SPECIFICATION ---"
					   checkMinus "$1"
					   pfov=`expr "$1" : '\([.0-9]*\)'`
					   [ "$pfov" = "" ] && errMsg "--- PFOV=$pfov MUST BE A NON-NEGATIVE FLOAT ---"
					   pfovtestA=`echo "$pfov <= 0" | bc`
					   pfovtestB=`echo "$pfov >= 180" | bc`
					   [ $pfovtestA -eq 1 -o $pfovtestB -eq 1 ] && errMsg "--- PFOV=$pfov MUST BE A FLOAT GREATER THAN 0 AND LESS THAN 180 ---"
					   ;;
				-i)    # get vertical center of perspective correction in panorama (input) image
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID IYC SPECIFICATION ---"
					   checkMinus "$1"
					   iyc=`expr "$1" : '\([.0-9]*\)'`
					   [ "$iyc" = "" ] && errMsg "--- IYC=$iyc MUST BE A NON-NEGATIVE FLOAT ---"
					   iyctestA=`echo "$iyc <= 0" | bc`
					   [ $iyctestA -eq 1 ] && errMsg "--- IYC=$iyc MUST BE A FLOAT GREATER THAN 0 ---"
					   ;;
				-o)    # get vertical center of perspective correction in perspective (output) image
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID OYC SPECIFICATION ---"
					   checkMinus "$1"
					   oyc=`expr "$1" : '\([.0-9]*\)'`
					   [ "$oyc" = "" ] && errMsg "--- OYC=$oyc MUST BE A NON-NEGATIVE FLOAT ---"
					   oyctestA=`echo "$oyc <= 0" | bc`
					   [ $oyctestA -eq 1 ] && errMsg "--- OYC=$oyc MUST BE A FLOAT GREATER THAN 0 ---"
					   ;;
				-h)    # get height
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID HEIGHT SPECIFICATION ---"
					   checkMinus "$1"
					   height=`expr "$1" : '\([0-9]*\)'`
					   [ "$height" = "" ] && errMsg "--- HEIGHT=$height MUST BE A NON-NEGATIVE INTEGER ---"
					   heighttest=`echo "$height <= 0" | bc`
					   [ $heighttest -eq 1 ] && errMsg "--- HEIGHT=$height MUST BE AN INTEGER GREATER THAN 0 ---"
					   ;;
			   -vp)    # get  vpmethod
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID VIRTUAL-PIXEL SPECIFICATION ---"
					   checkMinus "$1"
					   vpmethod="$1"
					   ;;
				-b)    # get  bgcolor
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID BACKGROUND COLOR SPECIFICATION ---"
					   checkMinus "$1"
					   bgcolor="$1"
					   ;;
				 -)    # STDIN and end of arguments
					   break
					   ;;
				-*)    # any other - argument
					   errMsg "--- UNKNOWN OPTION ---"
					   ;;
		     	 *)    # end of arguments
					   break
					   ;;
			esac
			shift   # next option
	done
	#
	# get infile and outfile
	infile="$1"
	outfile="$2"
fi

# test that infile provided
[ "$infile" = "" ] && errMsg "NO INPUT FILE SPECIFIED"

# test that outfile provided
[ "$outfile" = "" ] && errMsg "NO OUTPUT FILE SPECIFIED"

tmpA="$dir/pano2rect_$$.mpc"
tmpB="$dir/pano2rect_$$.cache"
trap "rm -f $tmpA $tmpB;" 0
trap "rm -f $tmpA $tmpB; exit 1" 1 2 3 15
#trap "rm -f $tmpA $tmpB; exit 1" ERR

if convert -quiet "$infile" +repage "$tmpA"
	then

	im_version=`convert -list configure | \
		sed '/^LIB_VERSION_NUMBER */!d;  s//,/;  s/,/,0/g;  s/,0*\([0-9][0-9]\)/\1/g' | head -n 1`

	if [ "$im_version" -ge "07000000" ]; then
		identifying="magick identify"
	else
		identifying="identify"
	fi

	# compute width, height, bottom and vertical center of input (source) panorama image
	swidth=`$identifying -format %w $tmpA`
	sheight=`$identifying -format %h $tmpA`
	shl=`convert xc: -format "%[fx:$sheight-1]" info:`
	sh2=`convert xc: -format "%[fx:($sheight-1)/2]" info:`

	# compute vrange
	vrange=`convert xc: -format "%[fx:abs($vtop-($vbot))]" info:`

	# compute center of perspective in input panorama image
	if [ "$format" = "level" ]; then
		# compute row corresponding to vertical angle = 0 (horizontal)
		iyc=`convert xc: -format "%[fx:($vtop/$vrange)*$shl]" info:`
	elif [ "$format" = "tilt" ]; then
		[ "$iyc" = "" ] && iyc=$sh2
	fi

	# get pfov if not provided
	[ "$pfov" = "" ] && pfov=$vrange
	[ `echo "$pfov >= 180" | bc` -eq 1 ] && errMsg="--- PFOV=$pfov MUST BE LESS THAN 180 DEG ---"

	# compute inverse perspective focal length from fov
	pfoc=`convert xc: -format "%[fx:$sheight/(2*tan($pfov*pi/360))]" info:`
	pfocinv=`convert xc: -format "%[fx:(2*tan($pfov*pi/360))/$sheight]" info:`
	
	# compute output (destination) vertical center and image bottom
	[ "$height" = "" ] && height=$sheight
	width=$swidth
	dh2=`convert xc: -format "%[fx:($height-1)/2]" info:`
	dhl=`convert xc: -format "%[fx:$height-1]" info:`

	# compute center of perspective in output perspective image
	if [ "$format" = "level" ]; then
		[ "$oyc" = "" ] && oyc=$dhl		
	elif [ "$format" = "tilt" ]; then
		[ "$oyc" = "" ] && oyc=$dh2
	fi
	
	else
		errMsg "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE ---"
fi

# Pertinent equations:
# note phi=fov/2; fov=field of view (aperture)
# note r=N/2; N=min(width,height)
# perspective: r=f*tan(phi); f=r/tan(phi); f=(N/2)/tan((fov/2)*(pi/180))=N/(2*tan(fov*pi/360))

# see Bourke diagram at http://local.wasp.uwa.edu.au/~pbourke/projection/fish2/

# for testing
if false; then
echo "swidth=$swidth; sheight=$sheight; shl=$shl; sh2=$sh2"
echo "iyc=$iyc; vrange=$vrange; pfov=$pfov; pfoc=$pfoc; pfocinv=$pfocinv"
echo "height=$height; width=$width; dh2=$dh2; dhl=$dhl; oyc=$oyc"
echo "vpmethod=$vpmethod; bgcolor=$bgcolor"
fi

# process image
	convert \( -size ${width}x${height} xc: \) $tmpA \
	-virtual-pixel $vpmethod -background $bgcolor -monitor \
	-fx "yd=j-($oyc); v.p{i,(180*$shl/(pi*$vrange))*atan($pfocinv*yd)+$iyc}" +monitor \
	"$outfile"
exit 0