rad = 0.125
n = 6000
# 
len x[] n ; len y[] n
len vx[] n ; len vy[] n
background 059
color 999
on animate
   for i = 1 to 32
      ind = (ind + 1) mod1 n
      x[ind] = 50 + randomf
      y[ind] = i / 4
      vx[ind] = (randomf - 0.5) * 0.4
      vy[ind] = 2 + randomf * 0.1
   .
   clear
   for i = 1 to n
      move x[i] y[i]
      circle rad
      x[i] += vx[i] ; y[i] += vy[i]
      vy[i] -= 0.025
   .
.
