Set corners of :class:~.Rectangle in counterclockwise direction

[abhijithmuthyala]

Changelog / Overview

This improves the look of transformations between rectangles and other simple mobjects.

Motivation

Here's how the Transformation from Square to Circle looks currently

Test.mp4

Notice how the Square gets flipped during the Transform.

Explanation for Changes

This is because the corners of Rectangles are set in clockwise direction

manim/manim/mobject/geometry.py

Line 1823 in 9c96d16

Polygon.__init__(self, UL, UR, DR, DL, color=color, **kwargs)

whereas for Arcs the points are set in counterclockwise direction

manim/manim/mobject/geometry.py

Lines 288 to 295 in 9c96d16

	anchors = np.array(
	[
	np.cos(a) * RIGHT + np.sin(a) * UP
	for a in np.linspace(
	self.start_angle, self.start_angle + self.angle, self.num_components
	)
	]
	)

This is what causes the Square to be flipped during the Transform. This PR changes the cw-orientation of Rectangle's corners (UL, UR, DR, DL) to ccw-orientation (UR, UL, DL, DR)

Testing Status

• Local pass (Windows 10)
• This is how the Transformation looks now

Test.mp4

Further Comments

This PR is inspired from Kolibril13's idea to enhance transformation. I've looked into the entire geometry.py module to check if any other Mobject needs this switch in orientation. Turned out it's just the Rectangle. Let me know if I missed something.

Checklist

• I have read the Contributing Guidelines
• I have written a descriptive PR title (see top of PR template for examples)
• I have written a changelog entry for the PR or deem it unnecessary
• My new functions/classes either have a docstring or are private
• My new functions/classes have tests added and (optional) examples in the docs
• My new documentation builds, looks correctly formatted, and adds no additional build warnings

Reviewer Checklist

• The PR title is descriptive enough
• The PR is labeled correctly
• The changelog entry is completed if necessary
• Newly added functions/classes either have a docstring or are private
• Newly added functions/classes have tests added and (optional) examples in the docs
• Newly added documentation builds, looks correctly formatted, and adds no additional build warnings

[abhijithmuthyala]

My bad, I ran pytest in master by mistake. I'll fix the tests

[huguesdevimeux]

Really nice stuff

you can see why tests are failing with --show_diff flag, but I think it's fine to re-generate the graphical unit data for this test

[abhijithmuthyala]

I think the failing macos test can be fixed once #1255 is merged?

[jsonvillanueva]

LGTM, yes tests should pass after #1255

[huguesdevimeux]

tests still fail on macox -_-

[jsonvillanueva]

tests still fail on macox -_-

That's because the branch hasn't updated to include the changes from #1255; @abhi3019, please update when you can.

[abhijithmuthyala]

Done @jsonvillanueva

[behackl]

Something weird is happening here. I don't have the button for merging the latest master in the GH UI, and I also can't push to the branch. I'll merge it nonetheless now (thanks for your contribution!), and we can revert it in case it causes problems.

[jsonvillanueva]

@behackl
I wonder if this happens when PRs are not created with the checkbox Allow edits from maintainers. Looking at the GitHub REST API for this PR, I don't see the "maintainer_can_modify" key in the json anywhere. Seems like it should exist regardless if it was True/False: https://docs.github.com/en/rest/reference/pulls#update-a-pull-request

[behackl]

@behackl
I wonder if this happens when PRs are not created with the checkbox Allow edits from maintainers. Looking at the GitHub REST API for this PR, I don't see the "maintainer_can_modify" key in the json anywhere. Seems like it should exist regardless if it was True/False: https://docs.github.com/en/rest/reference/pulls#update-a-pull-request

That would be a good explanation.