+data/sprites/ship.png: ship.pov pnmoutline Makefile
+ povray -GA -D +A +UA +W32 +H32 $< >/dev/null 2>/dev/null
+ pngtopnm ship.png >ship.pnm
+ ./pnmoutline <ship.pnm >data/sprites/ship.pnm
+ pnmtopng -transparent =white data/sprites/ship.pnm >$@
+ rm ship.png ship.pnm data/sprites/ship.pnm