Prevent mutation of about_point in apply_points_function_about_point - Fixes #4445 #4478
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This adds regression tests for issue ManimCommunity#4445 where using get_vertices()[0] as about_point in transformation methods would cause incorrect results due to numpy array view mutation. Tests added: - test_rotate_about_vertex_view - test_scale_about_vertex_view - test_stretch_about_vertex_view - test_apply_matrix_about_vertex_view - test_opengl_rotate_about_vertex_view (OpenGL was not affected by the bug) Related to ManimCommunity#4445
When about_point parameter receives a numpy array view (e.g., from get_vertices()[0]), the in-place operation `mob.points -= about_point` would mutate the view, corrupting the transformation calculation. This fix copies about_point before using it to prevent view mutation. The OpenGL renderer was not affected by this bug because it uses `arr - about_point` (creates temporary) instead of `arr -= about_point` (mutates in-place). Fixes ManimCommunity#4445
for more information, see https://pre-commit.ci
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Nov 16, 2025
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Thanks for the PR with relevant test cases and a solution to the problem.
LGTM!
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Overview: What does this pull request change?
Fixes issue #4445.
Fix
about_pointview mutation inapply_points_function_about_pointWhen about_point parameter receives a numpy array view (e.g., from
get_vertices()[0]), the in-place operation
mob.points -= about_pointwould mutate the view, corrupting the transformation calculation.
This fix copies
about_pointbefore using it to prevent view mutationMotivation and Explanation: Why and how do your changes improve the library?
Bugfix.
Links to added or changed documentation pages
Not applicable
Further Information and Comments
Not applicable.
Reviewer Checklist