PPM byte beat 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?=$$(date +"%Y%m%d%s")
# Pixmap dimensions
W?=64
H?=64
# How many pixels?
S?=$$(($W * $H - 1))
# Out image dimensions
w?=192
h?=192

beat/jpg: beat
	sips -s formatOptions best -s format jpeg $$(ls -tr | tail -n 1) -o $D.jpg && sips -z $h $w $D.jpg
beat:
	@for i in `seq 0 $S`; do d=(); x=$$(($$i % $W)); y=$$(($$i / $W));\
		d+=($$(bc <<< "($$x * 64) % $$y * 255"));\
		c=`printf "%d\n" "$${d[@]}"`;\
		echo $$c $$c $$c;\
	done | tr "\n" " " | awk '{print "P3\n$W $H\n255\n"$$0}' > "$$(date +"%Y%m%d%s").ppm"