Float x[400], y[400], dx[400], dy[400]
graphon
a=0.0
Do k=0,399
   dx[k]=2*cos(a)
   dy[k]=2*sin(a)
   a=a+6.2832/200
   x[k]=(399-k)*dx[k]
   y[k]=(399-k)*dy[k]
Loop
ndx=0
Do
   read quitkey
   Do k=0,399
      putpixel(320+x[k],240+y[k],0)
      putpixel(320-x[k],240-y[k],0)
      putpixel(320+y[k],240-x[k],0)
      putpixel(320-y[k],240+x[k],0)
      x[k]=x[k]+dx[k]
      y[k]=y[k]+dy[k]
      putpixel(320+x[k],240+y[k],9)
      putpixel(320-x[k],240-y[k],9)
      putpixel(320+y[k],240-x[k],12)
      putpixel(320-y[k],240+x[k],12)
   Loop
   x[ndx]=0.0
   y[ndx]=0.0
   ndx=(ndx+1)%400
Loop