From: Hidetoshi NAGAI <nagai@...>
Date: 2005-05-06T23:41:53+09:00
Subject: Re: Ruby-tk question

From: Joe Van Dyk <joevandyk@gmail.com>
Subject: Re: Ruby-tk question
Date: Fri, 6 May 2005 14:45:18 +0900
Message-ID: <c715e6405050522443f393a8c@mail.gmail.com>
> It's horribly difficult for someone who hasn't done math in years.

Here is an example. :-)
-----------------------------------------------
require 'tk'

def rotate(deg, x, y, c_x = 0, c_y = 0)
  rad = (deg * Math::PI)/180.0
  s_rad = Math::sin(rad)
  c_rad = Math::cos(rad)

  x -= c_x
  y -= c_y

  [c_x + (x * c_rad - y * s_rad),  c_y + (x * s_rad + y * c_rad)]
end

coords = [[100, 100], [200, 100], [100, 140]]
center = [120, 120]

c = TkCanvas.new.pack
poly = TkcPolygon.new(c, coords, :fill=>'red')
TkcOval.new(c, 
            center[0] - 2, center[1] - 2, 
            center[0] + 2, center[1] + 2, 
            :fill=>'black')

deg = 0
TkTimer.start(50, -1, proc{
                deg = (deg + 5) % 360
                poly.coords(coords.collect{|x, y| rotate(deg, x, y, *center)})
              })

Tk.mainloop
-----------------------------------------------
-- 
Hidetoshi NAGAI (nagai@ai.kyutech.ac.jp)