Improve performance for :meth:~become (#2508)

* Improve become method

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Make match_num_points kwarg

* fix test

* typehint and kwarg

* Add tests for become

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* experiment

* Undo match_num_points

* readd return self

* test fix

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* undo changes to match points

* use skip point alignment

* delete accidental inclusion

* Added documentation

Co-authored-by: Benjamin Hackl <devel@benjamin-hackl.at>

* Minor correction

* fix indentation

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* fix formatting

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Benjamin Hackl <devel@benjamin-hackl.at>

manim/mobject/mobject.py

@@ -2471,10 +2471,26 @@ def construct(self):
         return self.shuffle(*args, **kwargs)
 
     # Alignment
-    def align_data(self, mobject: "Mobject"):
+    def align_data(self, mobject: "Mobject", skip_point_alignment: bool = False):
+        """Aligns the data of this mobject with another mobject.
+
+        Afterwards, the two mobjects will have the same number of submobjects
+        (see :meth:`.align_submobjects`), the same parent structure (see
+        :meth:`.null_point_align`). If ``skip_point_alignment`` is false,
+        they will also have the same number of points (see :meth:`.align_points`).
+
+        Parameters
+        ----------
+        mobject
+            The other mobject this mobject should be aligned to.
+        skip_point_alignment
+            Controls whether or not the computationally expensive
+            point alignment is skipped (default: False).
+        """
         self.null_point_align(mobject)
         self.align_submobjects(mobject)
-        self.align_points(mobject)
+        if not skip_point_alignment:
+            self.align_points(mobject)
         # Recurse
         for m1, m2 in zip(self.submobjects, mobject.submobjects):
             m1.align_data(m2)
@@ -2644,7 +2660,7 @@ def construct(self):
         if match_center:
             mobject.move_to(self.get_center())
 
-        self.align_data(mobject)
+        self.align_data(mobject, skip_point_alignment=True)
         for sm1, sm2 in zip(self.get_family(), mobject.get_family()):
             sm1.points = np.array(sm2.points)
             sm1.interpolate_color(sm1, sm2, 1)
@@ -2667,7 +2683,6 @@ def construct(self):
                     self.play(circ.animate.match_points(square))
                     self.wait(0.5)
         """
-        self.align_data(mobject)
         for sm1, sm2 in zip(self.get_family(), mobject.get_family()):
             sm1.points = np.array(sm2.points)
         return self

tests/test_vectorized_mobject.py

@@ -3,7 +3,7 @@
 import numpy as np
 import pytest
 
-from manim import Circle, Line, Mobject, Square, VDict, VGroup, VMobject
+from manim import Circle, Line, Mobject, RegularPolygon, Square, VDict, VGroup, VMobject
 from manim.constants import PI
 
 
@@ -265,3 +265,27 @@ def draw_circle(m: VMobject, n_points, x=0, y=0, r=1):
 
     # The number of points should be similar to the size of a and b
     assert len(o.points) <= (20 + 15 + 15) * 4
+
+
+def test_vmobject_same_points_become():
+    a = Square()
+    b = Circle()
+    a.become(b)
+    assert np.array_equal(a.points, b.points)
+    assert len(a.submobjects) == len(b.submobjects)
+
+
+def test_vmobject_same_num_submobjects_become():
+    a = Square()
+    b = RegularPolygon(n=6)
+    a.become(b)
+    assert np.array_equal(a.points, b.points)
+    assert len(a.submobjects) == len(b.submobjects)
+
+
+def test_vmobject_different_num_points_and_submobjects_become():
+    a = Square()
+    b = VGroup(Circle(), Square())
+    a.become(b)
+    assert np.array_equal(a.points, b.points)
+    assert len(a.submobjects) == len(b.submobjects)