From f429f46df8a890cf35efe4c4e09deca7a2c4031d Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Mon, 11 Feb 2019 21:15:15 -0800
Subject: [PATCH] Got rid of fade_no_recurse idea

---
 manimlib/mobject/mobject.py                  | 37 +++++++-------------
 manimlib/mobject/types/image_mobject.py      |  3 +-
 manimlib/mobject/types/vectorized_mobject.py | 19 +++++++---
 3 files changed, 28 insertions(+), 31 deletions(-)

diff --git a/manimlib/mobject/mobject.py b/manimlib/mobject/mobject.py
index 4ef6b762..332ac43d 100644
--- a/manimlib/mobject/mobject.py
+++ b/manimlib/mobject/mobject.py
@@ -661,34 +661,21 @@ class Mobject(Container):
         self.set_color(self.color)
         return self
 
-    # Some objects (e.g., VMobjects) have special fading
-    # behavior. We let every object handle its individual
-    # fading via fade_no_recurse (notionally a purely internal method),
-    # and then have fade() itself call this recursively on each submobject
-    #
-    # Similarly for fade_to_no_recurse and fade_to, the underlying functions
-    # used by default for fade()ing
-
-    def fade_to_no_recurse(self, color, alpha):
+    def fade_to(self, color, alpha, family=True):
         if self.get_num_points() > 0:
-            start = color_to_rgb(self.get_color())
-            end = color_to_rgb(color)
-            new_rgb = interpolate(start, end, alpha)
-            self.set_color(Color(rgb=new_rgb), family=False)
+            new_color = interpolate_color(
+                self.get_color(), color, alpha
+            )
+            self.set_color(new_color, family=False)
+        if family:
+            for submob in self.submobjects:
+                submob.fade_to(color, alpha)
         return self
 
-    def fade_to(self, color, alpha):
-        for mob in self.get_family():
-            mob.fade_to_no_recurse(color, alpha)
-        return self
-
-    def fade_no_recurse(self, darkness):
-        self.fade_to_no_recurse(BLACK, darkness)
-        return self
-
-    def fade(self, darkness=0.5):
-        for submob in self.get_family():
-            submob.fade_no_recurse(darkness)
+    def fade(self, darkness=0.5, family=True):
+        if family:
+            for submob in self.submobjects:
+                submob.fade(darkness, family)
         return self
 
     def get_color(self):
diff --git a/manimlib/mobject/types/image_mobject.py b/manimlib/mobject/types/image_mobject.py
index 606c8ac4..be9cab68 100644
--- a/manimlib/mobject/types/image_mobject.py
+++ b/manimlib/mobject/types/image_mobject.py
@@ -93,8 +93,9 @@ class ImageMobject(AbstractImageMobject):
         self.pixel_array[:, :, 3] = int(255 * alpha)
         return self
 
-    def fade_no_recurse(self, darkness=0.5):
+    def fade(self, darkness=0.5, family=True):
         self.set_opacity(1 - darkness)
+        super().fade(darkness, family)
         return self
 
     def interpolate_color(self, mobject1, mobject2, alpha):
diff --git a/manimlib/mobject/types/vectorized_mobject.py b/manimlib/mobject/types/vectorized_mobject.py
index b808507e..38ea4916 100644
--- a/manimlib/mobject/types/vectorized_mobject.py
+++ b/manimlib/mobject/types/vectorized_mobject.py
@@ -240,11 +240,20 @@ class VMobject(Mobject):
         self.set_stroke(opacity=opacity, family=family)
         return self
 
-    def fade_no_recurse(self, darkness):
-        opacity = 1.0 - darkness
-        self.set_fill(opacity=opacity)
-        self.set_stroke(opacity=opacity)
-        self.set_background_stroke(opacity=opacity)
+    def fade(self, darkness=0.5, family=True):
+        factor = 1.0 - darkness
+        self.set_fill(
+            opacity=factor * self.get_fill_opacity()
+        )
+        self.set_stroke(
+            opacity=factor * self.get_stroke_opacity()
+        )
+        self.set_background_stroke(
+            opacity=factor * self.get_stroke_opacity(
+                background=True
+            )
+        )
+        super().fade(darkness, family)
         return self
 
     def get_fill_rgbas(self):