Fixed bugs in Succession and AnimationGroup, and also created purely virtual Container class from which both Scene and MObject derive (conceptually unifying their remove/add methods)

animation/simple_animations.py

@@ -10,6 +10,8 @@ from animation import Animation
 from animation import sync_animation_run_times_and_rate_funcs
 from transform import Transform
 
+from traceback import *
+
 class Rotating(Animation):
     CONFIG = {
         "axis"       : OUT,
@@ -408,9 +410,8 @@ class Succession(Animation):
             run_time = kwargs.pop("run_time")
         else:
             run_time = sum(self.run_times)
-        self.num_anims = len(animations)
+        self.num_anims = len(animations) #TODO: If this is zero, some special handling below
         self.animations = animations
-        self.last_index = 0
         #Have to keep track of this run_time, because Scene.play
         #might very well mess with it.
         self.original_run_time = run_time
@@ -420,29 +421,55 @@ class Succession(Animation):
         critical_times = np.concatenate(([0], np.cumsum(self.run_times)))
         self.critical_alphas = map (lambda x : np.true_divide(x, run_time), critical_times)
 
-        mobject = Group(*[anim.mobject for anim in self.animations])
-        Animation.__init__(self, mobject, run_time = run_time, **kwargs)
+        # self.scene_mobjects_at_time[i] is the scene's mobjects at start of self.animations[i]
+        # self.scene_mobjects_at_time[i + 1] is the scene mobjects at end of self.animations[i]
+        self.scene_mobjects_at_time = [None for i in range(self.num_anims + 1)]
+        self.scene_mobjects_at_time[0] = Group()
+        for i in range(self.num_anims):
+            self.scene_mobjects_at_time[i + 1] = self.scene_mobjects_at_time[i].copy()
+            self.animations[i].clean_up(self.scene_mobjects_at_time[i + 1])
+        print "Here's scene_mobjects_at_time[]: "
+        for g in self.scene_mobjects_at_time:
+            print str(g.submobjects)
 
-    def rewind_to_start(self):
-        for anim in reversed(self.animations):
-            anim.update(0)
+        self.current_alpha = 0
+        self.current_anim_index = 0 #TODO: What if self.num_anims == 0?
+
+        self.mobject = Group()
+        self.jump_to_start_of_anim(0)
+        Animation.__init__(self, self.mobject, run_time = run_time, **kwargs)
+
+    def jump_to_start_of_anim(self, index):
+        self.current_anim_index = index
+        self.current_alpha = self.critical_alphas[index]
+
+        self.mobject.remove(*self.mobject.submobjects) # Should probably have a cleaner "remove_all" method…
+        self.mobject.add(self.animations[index].mobject)
+        for m in self.scene_mobjects_at_time[index].submobjects:
+            self.mobject.add(m)
+
+        self.animations[index].update(0)  
 
     def update_mobject(self, alpha):
-        self.rewind_to_start()
+        i = 0
+        while self.critical_alphas[i + 1] < alpha:
+            i = i + 1
+            # TODO: Special handling if alpha < 0 or alpha > 1, to use
+            # first or last sub-animation
 
-        for i in range(len(self.animations)):
-            sub_alpha = inverse_interpolate(
-                self.critical_alphas[i], 
-                self.critical_alphas[i + 1], 
-                alpha
-            )
-            if sub_alpha < 0:
-                return
+        # At this point, we should have self.critical_alphas[i] <= alpha <= self.critical_alphas[i +1]
 
-            sub_alpha = clamp(0, 1, sub_alpha) # Could possibly adopt a non-clamping convention here
-            self.animations[i].update(sub_alpha)
+        self.jump_to_start_of_anim(i)
+        sub_alpha = inverse_interpolate(
+            self.critical_alphas[i], 
+            self.critical_alphas[i + 1], 
+            alpha
+        )
+        self.animations[i].update(sub_alpha)
 
     def clean_up(self, *args, **kwargs):
+        # We clean up as though we've played ALL animations, even if
+        # clean_up is called in middle of things
         for anim in self.animations:
             anim.clean_up(*args, **kwargs)
 
@@ -460,3 +487,7 @@ class AnimationGroup(Animation):
     def update_mobject(self, alpha):
         for anim in self.sub_anims:
             anim.update(alpha)
+
+    def clean_up(self, *args, **kwargs):
+        for anim in self.sub_anims:
+            anim.clean_up(*args, **kwargs)

mobject/mobject.py

@@ -7,10 +7,11 @@ from colour import Color
 
 from helpers import *
 
+from container import *
 
 #TODO: Explain array_attrs
 
-class Mobject(object):
+class Mobject(Container):
     """
     Mathematical Object
     """
@@ -22,7 +23,7 @@ class Mobject(object):
         "target" : None,
     }
     def __init__(self, *submobjects, **kwargs):
-        digest_config(self, kwargs)
+        Container.__init__(self, *submobjects, **kwargs)
         if not all(map(lambda m : isinstance(m, Mobject), submobjects)):
             raise Exception("All submobjects must be of type Mobject")
         self.submobjects = list(submobjects)

scene/scene.py

@@ -20,8 +20,9 @@ from animation import Animation
 from animation.animation import sync_animation_run_times_and_rate_funcs
 from animation.transform import MoveToTarget
 from animation.continual_animation import ContinualAnimation
+from container import *
 
-class Scene(object):
+class Scene(Container):
     CONFIG = {
         "camera_class"     : Camera,
         "camera_config"    : {},
@@ -40,9 +41,9 @@ class Scene(object):
         "skip_to_animation_number" : None,
     }
     def __init__(self, **kwargs):
-        digest_config(self, kwargs)
+        Container.__init__(self, **kwargs) # Perhaps allow passing in a non-empty *mobjects parameter?
         self.camera = self.camera_class(**self.camera_config)
-        self.mobjects = []
+        self.mobjects = [] #TODO: fiddle with this line... to match name used in Container
         self.continual_animations = []
         self.foreground_mobjects = []
         self.num_plays = 0