tabakrolletjie/engine.py

   1 """ Engine for moving controll scenes and tranistions between them.
   2 """
   3
   4 import pygame.display
   5 import pygame.event
   6 import pygame.time
   7
   8 import pygame.locals as pgl
   9
  10 from .constants import FPS, DRAW_FPS, FONTS, FPS_FRAMES
  11 from .loader import loader
  12 from .events import QuitEvent, SceneChangeEvent
  13
  14
  15 class Engine(object):
  16     def __init__(self, screen, gamestate):
  17         self._screen = screen
  18         self._gamestate = gamestate
  19         self._scene = None
  20
  21     def set_scene(self, scene):
  22         if self._scene is not None:
  23             self._scene.exit(self._gamestate)
  24         self._scene = scene
  25         if scene is not None:
  26             self._scene.enter(self._gamestate)
  27
  28     def run(self):
  29         clock = pygame.time.Clock()
  30         fpses = [FPS] * FPS_FRAMES
  31         frame = 0
  32         font = loader.load_font(FONTS['sans'], size=16)
  33
  34         while True:
  35             events = pygame.event.get()
  36             for ev in events:
  37                 if QuitEvent.matches(ev) or ev.type == pgl.QUIT:
  38                     self.set_scene(None)
  39                     return
  40                 elif SceneChangeEvent.matches(ev):
  41                     self.set_scene(ev.scene)
  42                 else:
  43                     self._scene.event(ev, self._gamestate)
  44
  45             # Advance time on the world
  46             # Time is assumed to flow perfectly, so no dt parameter for now
  47             self._scene.tick(self._gamestate)
  48             self._scene.render(self._screen, self._gamestate)
  49             if DRAW_FPS:
  50                 fps = sum(fpses) / FPS_FRAMES
  51                 text = font.render("FPS: %.2f" % fps, True, (255, 255, 255))
  52                 self._screen.blit(text, (10, 10), None)
  53             pygame.display.flip()
  54             fpses[frame] = 1000.0 / clock.tick(FPS)
  55             frame += 1
  56             if frame >= FPS_FRAMES:
  57                 frame = 0