' autor: Albert
dim as integer xres,yres
screen 19
screeninfo xres,yres
screenres xres,yres

dim as double rad = atn(1)/45
dim as double c,s,deg2
dim as double x1,y1,sqrt
dim as ulongint deg, xctr=xres/2, yctr=yres/2, radius=400

deg2=0
for deg = 0 to 90 step 1
      
     c=((90-deg)*rad)*(rad*50)
     s=(deg*rad)*(rad*50)

     sqrt = sqr(1-(s*c+s*s)*c)
      
     x1=radius*c*sqrt/2
     y1=radius*s*sqrt/2 ' divide by 2 to 5 for rectangle | no divide for square
      
     'line(xctr,yctr)-(xctr+x1,yctr+y1),11
     'line(xctr,yctr)-(xctr+x1,yctr-y1),11
     'line(xctr,yctr)-(xctr-x1,yctr+y1),11
     'line(xctr,yctr)-(xctr-x1,yctr-y1),11
      
     circle(xctr+x1,yctr+y1),5,9,,,,f
     circle(xctr+x1,yctr-y1),5,9,,,,f
     circle(xctr-x1,yctr+y1),5,9,,,,f
     circle(xctr-x1,yctr-y1),5,9,,,,f
      
     sleep 10
next
     circle(xctr,yctr),25,9
     paint(xctr+30,yctr+30),9,9

sleep