From 8b83c5e27d4c092b7c73a8706658ff9a4edf1346 Mon Sep 17 00:00:00 2001
From: Grant Sanderson <grant@3blue1brown.com>
Date: Wed, 13 Jan 2021 11:55:45 -1000
Subject: [PATCH] Performance improvement for Write

---
 manimlib/animation/creation.py | 35 ++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/manimlib/animation/creation.py b/manimlib/animation/creation.py
index 4165415c..f888bb73 100644
--- a/manimlib/animation/creation.py
+++ b/manimlib/animation/creation.py
@@ -16,6 +16,14 @@ class ShowPartial(Animation):
     """
     Abstract class for ShowCreation and ShowPassingFlash
     """
+    CONFIG = {
+        "should_match_start": False,
+    }
+
+    def begin(self):
+        super().begin()
+        if not self.should_match_start:
+            self.mobject.lock_matching_data(self.mobject, self.starting_mobject)
 
     def interpolate_submobject(self, submob, start_submob, alpha):
         submob.pointwise_become_partial(
@@ -38,7 +46,8 @@ class ShowCreation(ShowPartial):
 class Uncreate(ShowCreation):
     CONFIG = {
         "rate_func": lambda t: smooth(1 - t),
-        "remover": True
+        "remover": True,
+        "should_match_start": True,
     }
 
 
@@ -53,18 +62,18 @@ class DrawBorderThenFill(Animation):
     }
 
     def __init__(self, vmobject, **kwargs):
-        self.check_validity_of_input(vmobject)
+        assert(isinstance(vmobject, VMobject))
+        self.sm_to_index = dict([
+            (hash(sm), 0)
+            for sm in vmobject.get_family()
+        ])
         super().__init__(vmobject, **kwargs)
 
-    def check_validity_of_input(self, vmobject):
-        if not isinstance(vmobject, VMobject):
-            raise Exception(
-                "DrawBorderThenFill only works for VMobjects"
-            )
-
     def begin(self):
         self.outline = self.get_outline()
         super().begin()
+        self.mobject.match_style(self.outline)
+        self.mobject.lock_matching_data(self.mobject, self.outline)
 
     def get_outline(self):
         outline = self.mobject.copy()
@@ -88,11 +97,17 @@ class DrawBorderThenFill(Animation):
 
     def interpolate_submobject(self, submob, start, outline, alpha):
         index, subalpha = integer_interpolate(0, 2, alpha)
+
+        if index == 1 and self.sm_to_index[hash(submob)] == 0:
+            # First time crossing over
+            submob.set_data(outline.data)
+            submob.unlock_data()
+            submob.lock_matching_data(submob, start)
+            self.sm_to_index[hash(submob)] = 1
+
         if index == 0:
             submob.pointwise_become_partial(outline, 0, subalpha)
-            submob.match_style(outline)
         else:
-            submob.pointwise_become_partial(outline, 0, 1)
             submob.interpolate(outline, start, subalpha)