#!/bin/sh

[ ! "${w}" ] && exit
[ ! "${h}" ] && exit
[ ! "${mar}" ] && exit
w="$(( ${w} - 10 ))"; export w
h="$(( ${h} - 10 ))"; export h

xinc="$( echo "6 k ${w} ${mar} - ${mar} - 45 / p q" | dc )"; export xinc
###xstart="$( echo "6 k ${xinc} 2 / ${mar} + p q" | dc )"; export xstart
xstart="$(( ${mar} + 10 ))"; export xstar
xend="$( echo "0 k ${w} ${mar} - 10 + p q" | dc )"; export xend

yinc="$( echo "6 k ${h} ${mar} - ${mar} - 45 / p q" | dc )"; export yinc
###ystart="$( echo "6 k ${yinc} 2 / ${mar} + p q" | dc )"; export ystart
ystart="$(( ${mar} + 1 ))"; export ystart
yend="$( echo "0 k ${h} ${mar} - 10 + p q" | dc )"; export yend

y=${ystart}
yn="$( echo "0 k ${y} 1 / p q" | dc )"; export yn
while [ ${yn} -lt ${yend} ]
do

x=${xstart}
xn="$( echo "0 k ${x} 1 / p q" | dc )"; export xn
while [ ${xn} -lt ${xend} ]
do
echo "-fill 'black' \\"
echo "-draw \"line ${xn},${yn} ${xn},$(( ${yn} + ${mar}))\" \\"
echo "-draw \"line ${xn},${yn} ${xn},$(( ${yn} - ${mar}))\" \\"
echo "-draw \"line ${xn},${yn} $(( ${xn} + ${mar})),${yn}\" \\"
echo "-draw \"line ${xn},${yn} $(( ${xn} - ${mar})),${yn}\" \\"
x="$( echo "6 k ${x} ${xinc} + p q" | dc )"
xn="$( echo "0 k ${x} 1 / p q" | dc )"; export xn
done

y="$( echo "6 k ${y} ${yinc} + p q" | dc )"
yn="$( echo "0 k ${y} 1 / p q" | dc )"; export yn
done