use remapping instead of copying points

Author: MrDiver

manim/mobject/opengl/opengl_mobject.py

@@ -2348,7 +2348,7 @@ def construct(self):
                 continue
 
             if key in ("points", "bounding_box"):
-                self.data[key] = path_func(
+                self.data[key][:] = path_func(
                     mobject1.data[key], mobject2.data[key], alpha
                 )
             else:

manim/mobject/opengl/opengl_vectorized_mobject.py

@@ -21,6 +21,8 @@
     interpolate,
     partial_quadratic_bezier_points,
     proportions_along_bezier_curve_for_point,
+    quadratic_bezier_remap,
+    subdivide_quadratic_bezier,
 )
 from manim.utils.color import *
 from manim.utils.config_ops import _Data
@@ -1281,10 +1283,7 @@ def interpolate(self, mobject1, mobject2, alpha, *args, **kwargs):
         return self
 
     def pointwise_become_partial(
-        self,
-        vmobject: OpenGLVMobject,
-        a: float,
-        b: float,
+        self, vmobject: OpenGLVMobject, a: float, b: float, remap=True
     ) -> OpenGLVMobject:
         """Given two bounds a and b, transforms the points of the self vmobject into the points of the vmobject
         passed as parameter with respect to the bounds. Points here stand for control points of the bezier curves (anchors and handles)
@@ -1297,6 +1296,9 @@ def pointwise_become_partial(
             upper-bound.
         b : float
             lower-bound
+        remap : bool
+            if the point amount should be kept the same (True)
+            This option should be manually set to False if keeping the number of points is not needed
         """
         assert isinstance(vmobject, OpenGLVMobject)
         # Partial curve includes three portions:
@@ -1314,7 +1316,6 @@ def pointwise_become_partial(
         # Ex: if lower_index is 3, and lower_residue is 0.4, then the algorithm will append to the points 0.4 of the third bezier curve
         lower_index, lower_residue = integer_interpolate(0, num_quadratics, a)
         upper_index, upper_residue = integer_interpolate(0, num_quadratics, b)
-
         self.clear_points()
         if num_quadratics == 0:
             return self
@@ -1333,8 +1334,14 @@ def pointwise_become_partial(
                 ),
             )
             # TODO: replace by smooth_bezier_remap(triplets[li+1:ui], num_quadratics-2) -> [points; len(ui-li+1)] : #2742
-            for triplet in bezier_triplets[lower_index + 1 : upper_index]:
-                self.append_points(triplet)
+            inner_points = bezier_triplets[lower_index + 1 : upper_index]
+
+            if remap:
+                new_triplets = quadratic_bezier_remap(inner_points, num_quadratics - 2)
+            else:
+                new_triplets = bezier_triplets
+
+            self.append_points(np.asarray(new_triplets).reshape(-1, 3))
             self.append_points(
                 partial_quadratic_bezier_points(
                     bezier_triplets[upper_index], 0, upper_residue

manim/utils/bezier.py

@@ -175,6 +175,20 @@ def subdivide_quadratic_bezier(points: Iterable[float], n: int) -> np.ndarray:
     return np.asarray(beziers).reshape(-1, 3)
 
 
+def quadratic_bezier_remap(triplets, new_number_of_curves):
+    new_triplets = []
+    difference = new_number_of_curves - len(triplets)
+    for triplet in triplets:
+        if difference > 0:
+            tmp = subdivide_quadratic_bezier(triplet, 2)
+            new_triplets.append(tmp[:3])
+            new_triplets.append(tmp[3:])
+            difference -= 1
+        else:
+            new_triplets.append(triplet)
+    return new_triplets
+
+
 # Linear interpolation variants