Changed how functions are applied to vectorized mobjects to handle smoothness issues more cleanly

mobject/vectorized_mobject.py

@@ -14,8 +14,9 @@ class VMobject(Mobject):
         "is_subpath"       : False,
         "close_new_points" : False,
         "mark_paths_closed" : False,
-        "considered_smooth" : True,
         "propagate_style_to_family" : False,
+        "pre_function_handle_to_anchor_scale_factor" : 0.01,
+        "make_smooth_after_applying_functions" : False,
     }
 
     ## Colors
@@ -191,7 +192,6 @@ class VMobject(Mobject):
         return self
 
     def make_smooth(self):
-        self.considered_smooth = True
         return self.change_anchor_mode("smooth")
 
     def make_jagged(self):
@@ -232,12 +232,35 @@ class VMobject(Mobject):
             self.submobjects
         )
 
-    def apply_function(self, function, maintain_smoothness = False):
+    def apply_function(self, function):
+        factor = self.pre_function_handle_to_anchor_scale_factor
+        self.scale_handle_to_anchor_distances(factor)
         Mobject.apply_function(self, function)
-        if maintain_smoothness and self.considered_smooth:
+        self.scale_handle_to_anchor_distances(1./factor)
+        if self.make_smooth_after_applying_functions:
             self.make_smooth()
         return self
 
+    def scale_handle_to_anchor_distances(self, factor):
+        """
+        If the distance between a given handle point H and its associated
+        anchor point A is d, then it changes H to be a distances factor*d
+        away from A, but so that the line from A to H doesn't change.
+
+        This is mostly useful in the context of applying a (differentiable) 
+        function, to preserve tangency properties.  One would pull all the 
+        handles closer to their anchors, apply the function then push them out
+        again.
+        """
+        if self.get_num_points() == 0:
+            return
+        anchors, handles1, handles2 = self.get_anchors_and_handles()
+        # print len(anchors), len(handles1), len(handles2)
+        a_to_h1 = handles1 - anchors[:-1]
+        a_to_h2 = handles2 - anchors[1:]
+        handles1 = anchors[:-1] + factor*a_to_h1
+        handles2 = anchors[1:] + factor*a_to_h2
+        self.set_anchors_and_handles(anchors, handles1, handles2)
 
     ## Information about line
 
@@ -272,7 +295,6 @@ class VMobject(Mobject):
 
         
     ## Alignment    
-
     def align_points(self, mobject):
         Mobject.align_points(self, mobject)
         is_subpath = self.is_subpath or mobject.is_subpath

topics/geometry.py

@@ -114,7 +114,6 @@ class Sector(VMobject):
 class Line(VMobject):
     CONFIG = {
         "buff" : 0,
-        "considered_smooth" : False,
         "path_arc" : None,
         "n_arc_anchors" : 10, #Only used if path_arc is not None
     }
@@ -132,7 +131,6 @@ class Line(VMobject):
                 path_func(self.start, self.end, alpha)
                 for alpha in np.linspace(0, 1, self.n_arc_anchors)
             ])
-            self.considered_smooth = True
         self.account_for_buff()
 
     def account_for_buff(self):
@@ -449,7 +447,6 @@ class Polygon(VMobject):
         "color" : GREEN_D,
         "mark_paths_closed" : True,
         "close_new_points" : True,
-        "considered_smooth" : False,
     }
     def __init__(self, *vertices, **kwargs):
         assert len(vertices) > 1
@@ -479,7 +476,6 @@ class Rectangle(VMobject):
         "width"  : 4.0,
         "mark_paths_closed" : True,
         "close_new_points" : True,
-        "considered_smooth" : False,
     }
     def generate_points(self):
         y, x = self.height/2., self.width/2.
@@ -586,7 +582,6 @@ class Grid(VMobject):
     CONFIG = {
         "height" : 6.0,
         "width"  : 6.0,
-        "considered_smooth" : False,
     }
     def __init__(self, rows, columns, **kwargs):
         digest_config(self, kwargs, locals())

topics/number_line.py

@@ -223,6 +223,7 @@ class NumberPlane(VMobject):
         "secondary_line_ratio" : 1,
         "written_coordinate_height" : 0.2,
         "propagate_style_to_family" : False,
+        "make_smooth_after_applying_functions" : True,
     }
     def generate_points(self):
         if self.x_radius is None:
@@ -360,9 +361,6 @@ class NumberPlane(VMobject):
                 mob.make_smooth()
         return self
 
-    def apply_function(self, function, maintain_smoothness = True):
-        VMobject.apply_function(self, function, maintain_smoothness = maintain_smoothness)
-
 
 
 

topics/objects.py

@@ -267,7 +267,6 @@ class VideoIcon(SVGMobject):
     CONFIG = {
         "file_name" : "video_icon",
         "width" : 2*SPACE_WIDTH/12.,
-        "considered_smooth" : False,
     }
     def __init__(self, **kwargs):
         SVGMobject.__init__(self, **kwargs)
@@ -275,8 +274,6 @@ class VideoIcon(SVGMobject):
         self.scale_to_fit_width(self.width)
         self.set_stroke(color = WHITE, width = 0)
         self.set_fill(color = WHITE, opacity = 1)
-        for mob in self:
-            mob.considered_smooth = False
 
 class VideoSeries(VGroup):
     CONFIG = {