Écran de veille : Fractale

dim a,b,c,x,y,xp,yp,midx,midy,z,i,j,icol
dim r1,g1,b1,r2,g2,b2,rx,gx,bx

label quit,time

border_hide 0
full_space 0
on_click 0,quit

2d_fill_color 0,0,0
2d_rectangle 0,0,screen_x,screen_y

timer 1
timer_interval 1,1000
on_timer 1,time

end

time:
a=rnd(1)
b=0.9998
c=2-2*a
y=rnd(1)*12+0.1
midx=screen_x/2
midy=screen_y/2
x=0
j=0
r1=rnd(255)
g1=rnd(255)
b1=rnd(255)
r2=rnd(255)
g2=rnd(255)
b2=rnd(255)
icol=0
for i=0 to 12000
  z=x
  x=b*y+j
  j=a*x+c*(x*x)/(1+x*x)
  y=j-z
  xp=(x*20)+midx
  yp=(y*20)+midy
  rx=int(r1+(r2-r1)*icol/1000)
  gx=int(g1+(g2-g1)*icol/1000)
  bx=int(b1+(b2-b1)*icol/1000)
  if icol=1000
    r1=r2
    g1=g2
    b1=b2
    r2=rnd(255)
    g2=rnd(255)
    b2=rnd(255)
    icol=0
  end_if
  2d_pen_color rx,gx,bx
  2d_point xp,yp
  icol=icol+1
next i
return

quit:
terminate