class Engine:
- """ A holder for game state. """
+ """ A holder for game state & scene management.
+ """
- def __init__(self, app, scene):
+ def __init__(self, app, scene, world):
self._app = app
self._scene = scene
+ self._world = world
+ self._viewport = (0, 0)
def _apply_events(self, events):
if not events:
ev.apply(self)
def change_scene(self, scene):
- self._scene.exit()
+ self._apply_events(self._scene.exit(self._world.proxy()))
self._scene = scene
- self._scene.enter()
+ self._apply_events(self._scene.enter(self._world.proxy()))
+
+ def change_world(self, *args, **kw):
+ self._world.apply_event(*args, **kw)
+
+ def quit_game(self):
+ from pgzero.game import exit
+ exit()
+
+ def move_screen(self, offset):
+ self._viewport = (self._viewport[0] + offset[0],
+ self._viewport[1] + offset[1])
@apply_events
def update(self, dt):
- return self._scene.update(dt)
+ return self._scene.update(self._world.proxy(), dt)
def draw(self):
- self._scene.draw(self._app.screen)
+ self._scene.draw(self._app.screen, self._viewport)
@apply_events
def on_mouse_down(self, pos, button):
ENGINE_METHOD = "change_scene"
-class Actors:
- """ A list of actors. """
+class WorldEvent(Event):
+ """ Be a hero. Change the world. """
- def __init__(self):
- self._actors = []
+ ENGINE_METHOD = "change_world"
+
+
+class QuitEvent(Event):
+ """ Quit the game. """
+
+ ENGINE_METHOD = "quit_game"
+
+
+class MoveViewportEvent(Event):
+ """ Change to a new scene. """
+
+ ENGINE_METHOD = "move_screen"
+
+
+class Layer:
+ """ A single layer of actors. """
+
+ def __init__(self, name):
+ self.name = name
+ self.actors = []
+
+ def __iter__(self):
+ return iter(self.actors)
+
+ def __getitem__(self, i):
+ return self.actors[i]
+
+ def __len__(self):
+ return len(self.actors)
def add(self, actor):
- self._actors.append(actor)
+ self.actors.append(actor)
return actor
+ def clear(self):
+ self.actors.clear()
+
def remove(self, actor):
- self._actors.remove(actor)
+ self.actors.remove(actor)
return actor
+
+class Actors:
+ """ Layers of actors.
+
+ Actors may be rendered in different layers. Layers with lower levels
+ are rendered lower than layers with higher ones.
+ """
+
+ def __init__(self):
+ self._ordered_layers = []
+ self._layers = {}
+ self.add_layer("default", 0)
+
+ def __getattr__(self, name):
+ return self._layers[name]
+
+ def add_layer(self, name, level):
+ layer = self._layers[name] = Layer(name)
+ self._ordered_layers.append((level, name))
+ self._ordered_layers.sort()
+ return layer
+
+ def add(self, actor, layer="default"):
+ return self._layers[layer].add(actor)
+
+ def remove(self, actor, layer="default"):
+ return self._layers[layer].remove(actor)
+
def draw(self, screen):
- for actor in self._actors:
- actor.draw() # TODO: allow an option screen to be passed in
+ for lvl, name in self._ordered_layers:
+ for actor in self._layers[name]:
+ actor.draw() # TODO: allow an option screen to be passed in
class Scene:
def __init__(self):
self.actors = Actors()
- def enter(self):
+ def enter(self, world):
pass
- def exit(self):
+ def exit(self, world):
pass
- def update(self, dt):
+ def update(self, world, dt):
pass
- def draw(self, screen):
+ def draw(self, screen, viewport):
screen.clear()
self.actors.draw(screen)