The first steps towards enemy generators

[koperkapel.git] / koperkapel / scenes / base.py

diff --git a/koperkapel/scenes/base.py b/koperkapel/scenes/base.py
index 19ba212fce407eb91047652b5a114ceed719284c..623eb42a977276e506449831be35956d83758d32 100644 (file)
--- a/koperkapel/scenes/base.py
+++ b/koperkapel/scenes/base.py
@@ -20,7 +20,7 @@ class Engine:
         self._app = app
         self._scene = scene
         self._world = world
-        self._viewport = (0, 0)
+        self._update_vehicle = False
 
     def _apply_events(self, events):
         if not events:
@@ -41,15 +41,14 @@ class Engine:
         exit()
 
     def move_screen(self, offset):
-        self._viewport = (self._viewport[0] + offset[0],
-                          self._viewport[1] + offset[1])
+        self._scene.move_screen(offset)
 
     @apply_events
     def update(self, dt):
-        return self._scene.update(self._world.proxy(), dt)
+        return self._scene.update(self._world.proxy(), self, dt)
 
     def draw(self):
-        self._scene.draw(self._app.screen, self._viewport)
+        self._scene.draw(self._app.screen)
 
     @apply_events
     def on_mouse_down(self, pos, button):
@@ -109,23 +108,75 @@ class MoveViewportEvent(Event):
     ENGINE_METHOD = "move_screen"
 
 
-class Actors:
-    """ A list of actors. """
+class Layer:
+    """ A single layer of actors. """
 
-    def __init__(self):
-        self._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 doesn't allow blitting to anything other than
+                # the game scene
+                screen.blit(actor._surf, actor.topleft)
+
+
+def defer_to_update(f):
+    """ Defers a function until the next update run. """
+    @functools.wraps(f)
+    def wrapper(self, *args, **kw):
+        self._deferred_updates.append((f, args, kw))
+    return wrapper
 
 
 class Scene:
@@ -133,6 +184,16 @@ class Scene:
 
     def __init__(self):
         self.actors = Actors()
+        self.viewport = (0, 0)
+        self._deferred_updates = []
+
+    def move_screen(self, offset):
+        self.viewport = (self.viewport[0] + offset[0],
+                         self.viewport[1] + offset[1])
+
+    def calc_offset(self, x, y):
+        """ Return a position offset by the viewport. """
+        return x - self.viewport[0], y - self.viewport[1]
 
     def enter(self, world):
         pass
@@ -140,10 +201,12 @@ class Scene:
     def exit(self, world):
         pass
 
-    def update(self, world, dt):
-        pass
+    def update(self, world, engine, dt):
+        deferred_updates, self._deferred_updates = self._deferred_updates, []
+        for f, args, kw in deferred_updates:
+            f(self, world, *args, **kw)
 
-    def draw(self, screen, viewport):
+    def draw(self, screen):
         screen.clear()
         self.actors.draw(screen)