Refactoring The Prototype - Developing Games With Ruby - page 88

11 def update
12

d_x, d_y = @camera . target_delta_on_screen

atan = Math . atan2(( $window . width / 2 ) - d_x - $window . mouse_x, 13

( $window . height / 2 ) - d_y - $window . mouse_y) 14

object . gun_angle = - atan * 180 / Math :: PI

15

motion_buttons = [ Gosu :: KbW , Gosu :: KbS , Gosu :: KbA , Gosu :: KbD ] 16

17
18 if any_button_down?( * motion_buttons)
19 object . throttle_down = true
20 object . direction = change_angle(object . direction,
* motion_buttons)
21 else
22 object . throttle_down = false
23 end
24
25 if Utils . button_down?( Gosu :: MsLeft )
26 object . shoot( * @camera . mouse_coords)
27 end
28 end
29
30 private

31
32 def any_button_down? ( * buttons)
33 buttons . each do | b |
34 return true if Utils . button_down?(b)
35 end
36 false
37 end
38
39 def change_angle (previous_angle, up, down, right, left)
40 if Utils . button_down?(up)
41 angle = 0.0
42 angle += 45.0 if Utils . button_down?(left)
43 angle -= 45.0 if Utils . button_down?(right)
44 elsif Utils . button_down?(down)
45 angle = 180.0
46 angle -= 45.0 if Utils . button_down?(left)
47 angle += 45.0 if Utils . button_down?(right)
48 elsif Utils . button_down?(left)
49 angle = 90.0
50 angle += 45.0 if Utils . button_down?(up)
51 angle -= 45.0 if Utils . button_down?(down)
52 elsif Utils . button_down?(right)
53 angle = 270.0

angle -= 45.0 if Utils . button_down?(up)

54

angle += 45.0 if Utils . button_down?(down) 55