Fix successive calls of :meth:.LinearTransformationScene.apply_matrix

manim/scene/vector_space_scene.py

@@ -1003,8 +1003,11 @@ def get_piece_movement(self, pieces: list | tuple | np.ndarray):
         Animation
             The animation of the movement.
         """
-        start = VGroup(*pieces)
-        target = VGroup(*(mob.target for mob in pieces))
+
+        v_pieces = [piece for piece in pieces if isinstance(piece, VMobject)]
+        start = VGroup(*v_pieces)
+        target = VGroup(*(mob.target for mob in v_pieces))
+
         # don't add empty VGroups
         if self.leave_ghost_vectors and start.submobjects:
             # start.copy() gives a VGroup of Vectors
@@ -1091,6 +1094,7 @@ def apply_matrix(self, matrix: np.ndarray | list | tuple, **kwargs):
         **kwargs
             Any valid keyword argument of self.apply_transposed_matrix()
         """
+
         self.apply_transposed_matrix(np.array(matrix).T, **kwargs)
 
     def apply_inverse(self, matrix: np.ndarray | list | tuple, **kwargs):

tests/test_graphical_units/test_vector_scene.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from manim.scene.vector_space_scene import VectorScene
+from manim.scene.vector_space_scene import LinearTransformationScene, VectorScene
 from manim.utils.testing.frames_comparison import frames_comparison
 
 __module_test__ = "vector_scene"
@@ -14,3 +14,13 @@ def test_vector_to_coords(scene):
     scene.add(basis)
     scene.vector_to_coords(vector=vector)
     scene.wait()
+
+
+def test_apply_matrix():
+    scene = LinearTransformationScene(include_background_plane=False)
+    scene.setup()
+    matrix = [[-1, 1], [1, 1]]
+    # use short runtimes to speed up animation rendering
+    scene.apply_matrix(matrix, run_time=0.01)
+    scene.wait()
+    scene.apply_inverse(matrix, run_time=0.01)