GIFs animées, dessiner une planète

ppmforge generates three kinds of "random fractal forgeries," the term coined by Richard F. Voss of the IBM Thomas J. Watson Research Center for seemingly realistic pictures of natural objects generated by simple algorithms embodying randomness and fractal self-similarity. The techniques used by ppmforge are essentially those given by Voss[1], particularly the technique of spectral synthesis explained in more detail by Dietmar Saupe[2].

ppmforge: planet: -seed 666 -dimension 2.40 -power 0.80 -mesh 1024
ppmforge:         -inclination 4 -hour 15 -ice 0.87 -glaciers 0.75
ppmforge:         -stars 100 -saturation 125.
#!/bin/bash

WIDTH=460
HEIGHT=460
SEED=666
MESH=2048
DIMENSION=2.80
POWER=0.65

NOMBRE=96
DELAY=15	# for GIF animation

source functions_gif.bash

for i in $(seq 1 $NOMBRE)
do
	dest=/tmp/planete$(printf "%03d" $i).ppm
	
	hour=$i
	ice=$( echo "($i / $NOMBRE) + 0.001" | bc -l )
	ppmforge -hour $hour -seed $SEED -mesh $MESH	\
			-dimension $DIMENSION		\
			-power $POWER -ice $ice		\
			-width $WIDTH -height $HEIGHT > $dest

	annotate $i $dest
done

convert -delay $DELAY /tmp/planete*.ppm planete.gif