split_tiles.sh

#!/bin/sh
#
# Script for splitting a tileset image into multiple image files.

function show_usage() {
  local ME=`basename "$0"`
  echo "USAGE: $ME <in file> <output dir> --width <value> --height <value> {options}"
  echo " "
  echo "OPTIONS:"
  echo " "
  echo "  -h, --help     show usage information"
  echo "  -z, --zeropad  number of digits with zero padding;"
  echo "                 integer>=0; default=0 (no zero padding)"
  echo " "
}

function show_error() {
  echo "$1"
  echo " "
  show_usage
  exit 1
}

function parse_args() {
  while test $# -gt 0; do
    case "$1" in
      -h|--help)
        show_usage
        exit 0
        ;;
      --width)
        shift
        if test $# -gt 0; then
          WIDTH=$1
        else
          show_error "No width specified."
        fi
        shift
        ;;
      --height)
        shift
        if test $# -gt 0; then
          HEIGHT=$1
        else
          show_error "No height specified."
        fi
        shift
        ;;
      -z|--zeropad)
        shift
        if test $# -gt 0; then
          ZEROPAD=$1
        fi
        shift
        ;;
      *)
        break
        ;;
    esac
  done
  
  if [ -z "$WIDTH" ]; then
    show_error "No width specified."
  fi
  if [ -z "$HEIGHT" ]; then
    show_error "No height specified."
  fi
}

if [ "$#" -lt 2 ]; then
  show_error "Invalid number of parameters."
fi

FILE="$1"
OUTPUT_DIR="$2"
shift
shift

ZEROPAD=0

parse_args "$@"

ZEROPAD="%0"$ZEROPAD"d"

echo "Processing: $FILE"
convert "$FILE" -crop $WIDTH"x"$HEIGHT $OUTPUT_DIR$ZEROPAD".png"