X-Git-Url: https://git.ctpug.org.za/?a=blobdiff_plain;f=koperkapel%2Fscenes%2Fbase.py;h=ade4d8bfddede638919ab9eb884423d38a9e55c6;hb=0e3ff44e339e83cc26196e9fcd20193dbd65a46c;hp=19ba212fce407eb91047652b5a114ceed719284c;hpb=1dde3db82037abbc3a493ea6479cd828794b0bd1;p=koperkapel.git

diff --git a/koperkapel/scenes/base.py b/koperkapel/scenes/base.py
index 19ba212..ade4d8b 100644
--- a/koperkapel/scenes/base.py
+++ b/koperkapel/scenes/base.py
@@ -44,9 +44,13 @@ class Engine:
         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]
+
     @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)
@@ -109,23 +113,65 @@ 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()  # TODO: allow an option screen to be passed in
 
 
 class Scene:
@@ -140,7 +186,7 @@ class Scene:
     def exit(self, world):
         pass
 
-    def update(self, world, dt):
+    def update(self, world, engine, dt):
         pass
 
     def draw(self, screen, viewport):