#!/bin/sh -
#
# pnmsplitup  size  file
#
#  splitup a pnm file into small pixmaps
#
if [ $# -ne 2 ]; then
  echo "usage: $0 size pnmfile"
fi

PIC=$2
size=$1    # size of the bits

OUT=.
#mkdir $OUT

Xsize=`expr "\`pnmfile $PIC\`" : '.*, \([0-9]*\)'`
Ysize=`expr "\`pnmfile $PIC\`" : '.*by \([0-9]*\)'`

X=`expr $Xsize / $size`   # columns
Y=`expr $Ysize / $size`   # rows

x=0; y=0; i=0
while [ $y -lt $Y ]; do
  x=0;
  while [ $x -lt $X ]; do
    # split a pixmap from picture
    i=`echo $i | awk '{ printf "%03d", $1 + 1 }'`
    echo "$x x $y  -> $i.ppm"
    pnmcut `expr $x \* $size` `expr $y \* $size` $size $size $PIC > $OUT/$i.ppm
    x=`expr $x + 1`
  done
  y=`expr $y + 1`
done