#!/bin/sh

if [ $# -ne 5 ]
then
    echo "usage: scale_click.sh xmin xmax ymin ymax file"
    exit 1
fi

# reference points in the final units from the command line
XMIN=$1
XMAX=$2
YMIN=$3
YMAX=$4
FILE=$5

# reference points in pixels from the first 4 clicks
XMINP=`sed -n '1p' $FILE | cut -f1`
XMAXP=`sed -n '2p' $FILE | cut -f1`
YMINP=`sed -n '3p' $FILE | cut -f2`
YMAXP=`sed -n '4p' $FILE | cut -f2`

echo "# Xp -> ($XMAX-$XMIN)/($XMAXP-$XMINP)*(Xp-$XMINP) + $XMIN"
echo "# Yp -> ($YMAX-$YMIN)/($YMAXP-$YMINP)*(Yp-$YMINP) + $YMIN"

awk "{if(NR > 4){print ($XMAX-$XMIN)/($XMAXP-$XMINP)*(\$1-$XMINP) + $XMIN, \
                       ($YMAX-$YMIN)/($YMAXP-$YMINP)*(\$2-$YMINP) + $YMIN}}" \
    $FILE

exit 0