Worley noise maker

helper.bc

/* Call like so: `echo 'clamp(256, 0, 255)' | bc -l helper.bc` */
define clamp(v, lo, hi) {
  if (v < lo) {
    return (lo)
  }

  if (v > hi) {
    return (hi)
  }

  return (v)
}

define remap(v, x1, x2, y1, y2) {
  return (v - x1) * (y2 - y1) / (x2 - x1) + y1
}

Makefile

# The filenaming timestamp
D?=$$(date +"%Y%m%d%s")
# How many feature points?
R?=10
# Pixmap dimensions
W?=80
H?=45
# How many pixels?
S?=$$(($W * $H - 1))
# Out image dimensions
w?=800
h?=450

gradient/jpg: gradient
	sips -s formatOptions best -s format jpeg $$(ls -tr | tail -n 1) -o $D.jpg && sips -z $h $w $D.jpg
gradient:
	@list=`make features`; for i in `seq 0 $S`; do d=(); x=$$(($$i % $W)); y=$$(($$i / $W));\
		while read line; do p=($$line);\
			d+=($$(bc <<< "scale=6; sqrt(($${p[0]} - $$x) ^ 2 + ($${p[1]} - $$y) ^ 2)"));\
		done <<< "$$list";\
		v=`printf "%f\n" "$${d[@]}" | sort -n | head -n 1`;\
		c=`printf "%.0f\n" "$$(bc -l helper.bc <<< "clamp(remap($$v, 0, $W / 4, 255, 0), 0, 255)")"`;\
		echo $$c $$c $$c;\
	done | tr "\n" " " | awk '{print "P3\n$W $H\n255\n"$$0}' > "$$(date +"%Y%m%d%s").ppm"
features:
	@{ jot -r $R 0 $$(($W - 1)); jot -r $R 0 $$(($H - 1)); } | pr -t -2 -s" "