Tile extension script (add padding to a tileset/spritesheet)

extend_tiles.sh

#!/bin/bash

# Add padding to a tileset. This script assumes that the input file is a png
# Usage: extend_tiles.sh [image_file.png] [width] [height] [new_width] [new_height] [columns]
#                        1                2       3        4           5            6

if [ "$#" -ne 6 ]; then
  echo Usage: extend_tiles.sh [image_file.png] [width] [height] [new_width] [new_height] [columns]
  exit 1
fi

TMP=/tmp/extend_tiles

rm -rf $TMP
mkdir $TMP

cp $1 $TMP

pushd $TMP > /dev/null

mkdir tiles
mkdir padding

convert -crop $2x$3 $1 tiles/tile%03d.png
convert tiles/tile*.png -background transparent -gravity center -extent $4x$5 padding/padded_%03d.png
montage padding/padded_*.png -background transparent -mode concatenate -tile $6x $1

popd > /dev/null

cp $TMP/$1 $(basename $1 .png)_padded.png