// Entry code: acmkbd
// Name      : Paul Bourke
// Frame rate: 10
light_source {3*z, rgb 1}

sphere {0,9i pigment {rgb z/4} hollow}

media {scattering {4,0.08}}

#local N=0;
#local X=0;
#local Y=0;
#local R=seed(2);
#local S=sqrt(2);
union{
   #while (N < 1000*pow(10,clock*3))
      #if (rand(R) < 0.5)
         #local A=Y/S+1.5;
         #local B=1.5-X/S;
      #else
         #local A=.5-Y/S;
         #local B=X/S+.5;
      #end
      #if (rand(R) < 0.5)
         #local X=A-2;
         #local Y=B;
      #else
         #local D=pow(A-2,2)+B*B;
         #local X=(A-2)/D;
         #local Y=B/D;
      #end
      sphere { <X+1,Y-1,5>, 0.6*exp(-5*clock)+ 0.01}
      #local N=N+1;
   #end 
   pigment { rgb <.4,.3,.1>}
   finish{specular.8}
} // Union