setrgb 1,0,0,0
open window 640,512
label k
 setdispbuf bu:bu=1-bu:setdrawbuf bu
 setrgb 3,ran(20)+40,0,0
 for y=0 to 512 step 4
  m=m+1
  x=cos(m/19.6)*cos(m/19.8)*120+320
  setrgb 2,y,y/2,0
  gtriangle 0,y to x,y to 0,y+4
  gtriangle x,y+4 to x,y to 0,y+4
  gtriangle 640,y to x,y to 640,y+4
  gtriangle x,y+4 to x,y to 640,y+4
 next y
goto k

