_window = 1

void local fn BuildWindow
  CGRect r = fn CGRectMake( 0, 0, 705, 500 )
  window _window, @"Pythagoras Tree In FutureBasic", r, NSWindowStyleMaskTitled
  WindowSetBackgroundColor( _window, fn ColorBlack )
end fn

local fn PythagorasTree( x1 as double, y1 as double, x2 as double, y2 as double, depth as NSUInteger )
  if depth > 10 then exit fn

  double dx = x2 - x1, dy = y1 - y2
  double x3 = x2 - dy, y3 = y2 - dx
  double x4 = x1 - dy, y4 = y1 - dx
  double x5 = x4 + (dx - dy) / 2
  double y5 = y4 - (dx + dy) / 2

  select ( rnd(5) )
    case 1 : pen 2, fn ColorBrown
    case 2 : pen 2, fn ColorRed
    case 3 : pen 2, fn ColorOrange
    case 4 : pen 2, fn ColorYellow
    case 5 : pen 2, fn ColorGreen
  end select

  line x1, y1, x2, y2 : Line x2, y2, x3, y3
  line x3, y3, x4, y4 : Line x4, y4, x1, y1

  fn PythagorasTree( x4, y4, x5, y5, depth +1 )
  fn PythagorasTree( x5, y5, x3, y3, depth +1 )
end fn

local fn DrawTree
  NSUInteger  w = 700, h = w * 11 \ 16
  NSUInteger w2 = w \ 2, diff = w \ 12

  fn PythagorasTree( w2 - diff, h -10 , w2 + diff , h -10 , 0 )
end fn

random

fn BuildWindow
fn DrawTree

HandleEvents