Refactor of capture_mobjects to be cleaner about batching

camera/camera.py

@@ -177,29 +177,30 @@ class Camera(object):
 
     def capture_mobjects(self, mobjects, **kwargs):
         mobjects = self.get_mobjects_to_display(mobjects, **kwargs)
-        vmobjects = []
-        for mobject in mobjects:
-            if isinstance(mobject, VMobject):
-                 vmobjects.append(mobject)
-            elif len(vmobjects) > 0:
-                self.display_multiple_vectorized_mobjects(vmobjects)
-                vmobjects = []
-                
-            if isinstance(mobject, PMobject):
-                self.display_point_cloud(
-                    mobject.points, mobject.rgbas, 
-                    self.adjusted_thickness(mobject.stroke_width)
-                )
-            elif isinstance(mobject, ImageMobject):
-                self.display_image_mobject(mobject)
-            elif isinstance(mobject, Mobject):
-                pass #Remainder of loop will handle submobjects
-            else:
-                raise Exception(
-                    "Unknown mobject type: " + mobject.__class__.__name__
-                )
-            #TODO, more?  Call out if it's unknown?
-        self.display_multiple_vectorized_mobjects(vmobjects)
+
+        # Organize this list into batches of the same type, and 
+        # apply corresponding function to those batches
+        type_func_pairs = [
+            (VMobject, self.display_multiple_vectorized_mobjects),
+            (PMobject,  self.display_multiple_point_cloud_mobjects),
+            (ImageMobject,  self.display_multiple_image_mobjects),
+            (Mobject, lambda batch : batch), #Do nothing
+        ]
+        def get_mobject_type(mobject):
+            for mobject_type, func in type_func_pairs:
+                if isinstance(mobject, mobject_type):
+                    return mobject_type
+            raise Exception(
+                "Trying to display something which is not of type Mobject"
+            )
+        batches = batch_by_property(mobjects, get_mobject_type)
+
+        #Display in these batches
+        for batch in batches:
+            #check what the type is, and call the appropriate function
+            for mobject_type, func in type_func_pairs:
+                if isinstance(batch[0], mobject_type):
+                    func(batch)
 
     ## Methods associated with svg rendering
 
@@ -312,6 +313,14 @@ class Camera(object):
 
     ## Methods for other rendering
 
+    def display_multiple_point_cloud_mobjects(self, pmobjects):
+        for pmobject in pmobjects:
+            self.display_point_cloud(
+                pmobject.points,
+                pmobject.rgbas,
+                self.adjusted_thickness(pmobject.stroke_width)
+            )
+
     def display_point_cloud(self, points, rgbas, thickness):
         if len(points) == 0:
             return
@@ -342,6 +351,10 @@ class Camera(object):
         new_pa[indices] = rgbas
         self.pixel_array = new_pa.reshape((ph, pw, rgba_len))
 
+    def display_multiple_image_mobjects(self, image_mobjects):
+        for image_mobject in image_mobjects:
+            self.display_image_mobject(image_mobject)
+
     def display_image_mobject(self, image_mobject):
         corner_coords = self.points_to_pixel_coords(image_mobject.points)
         ul_coords, ur_coords, dl_coords = corner_coords