Спирограф

 Наткнулся на программу, запустилось не сразу.

;https://www.pythoninformer.com/python-projects/graphics-projects/spirographs/
Procedure.l GCD(x.l, y.l)
; The greatest common denominator (GCD) is the largest positive integer
; that divides into both numbers without a remainder.
; Examples: GCD(256,64)=64, GCD(12,8)=4, GCD(5,3)=1
 g.l
 ; Work With absolute values (positive integers)
 If x < 0 : x = -x : EndIf
 If y < 0 : y = -y : EndIf
 If x + y > 0
  g = y
  ; Iterate Until x = 0
  While x > 0
   g = x
   x = y % x
   y = g
  Wend
  ProcedureReturn g
 Else
  ; Error, both parameters zero
  ProcedureReturn 0
 EndIf

EndProcedure
If OpenWindow(0, 0, 0, 640, 480, "spirograph", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
  CanvasGadget(0, 0, 0, 640, 480)
  
  If StartDrawing(CanvasOutput(0))
    Box(0,0,640,480,0)
    a=16
    b=11
    d=7
    t.f=0
    dt.f=0.01
    scale=20
    While t<2*#PI*b/gcd(a, b)
       x.f = (a - b) * Cos(t) + d * Cos((a - b)/b * t)
       y.f = (a - b) * Sin(t) - d * Sin((a - b)/b * t)
       x=320+x*scale
       y=240+y*scale
       If t=0
         x0=x
         y0=y
       Else
         LineXY(x,y,x0,y0,255)
         x0=x
         y0=y
       EndIf         
      t+dt
    Wend
    StopDrawing()
  EndIf
  
    Repeat
      Event = WindowEvent()
  Until Event = #PB_Event_CloseWindow
EndIf