pythonmanim

How to move line to original position with manim?

I have 4 lines making up a rectangle. In the scene I want to show, that the lines are not attached to each other and so I move them a little bit away from each other, and then I want to move them back to their original position (making up the rectangle). Is there a way to move them to their original position without creating a new target position?

This is my code so far:

from manim import *

bufferCoordinates = [
    [5, -1.65180767, 0.0],
    [3.67578217, -3.77055619, 0.0],
    [-5.0, 1.65180767, 0.0],
    [-3.67578217, 3.77055619, 0.0],
]

config.frame_width = 18
config.frame_height = 12

class getLSWgeoms(ZoomedScene):
    def construct(self):
        
        # Polygon
        buffer = Polygon(*bufferCoordinates)
        buffer.set_fill(PINK, opacity=0.5)

        # Single Lines
        bufferline1 = Line(*[[5, -1.65180767, 0.0], [3.67578217, -3.77055619, 0.0]])
        bufferline1.generate_target()
        bufferline1.target.move_to(5.0 * RIGHT + 3 * DOWN)

        bufferline2 = Line(*[[3.67578217, -3.77055619, 0.0], [-5.0, 1.65180767, 0.0]])
        bufferline2.generate_target()
        bufferline2.target.move_to(1.5 * DOWN + 1 * LEFT)

        bufferline3 = Line(*[[-5.0, 1.65180767, 0.0], [-3.67578217, 3.77055619, 0.0]])
        bufferline3.generate_target()
        bufferline3.target.move_to(5 * LEFT + 3 * UP)

        bufferline4 = Line(*[[-3.67578217, 3.77055619, 0.0],[5, -1.65180767, 0.0]])
        bufferline4.generate_target()
        bufferline4.target.move_to(1.5 * UP + 1 * RIGHT)
        
        # Play Scenes
        self.play(FadeIn(buffer), run_time=1)
        self.play(
            MoveToTarget(bufferline1),
            MoveToTarget(bufferline2),
            MoveToTarget(bufferline3),
            MoveToTarget(bufferline4),
            run_time=3
        )

enter image description here

Solution

  • Simple solution using save_state() and Restore():

    from manim import *

bufferCoordinates = [
    [5, -1.65180767, 0.0],
    [3.67578217, -3.77055619, 0.0],
    [-5.0, 1.65180767, 0.0],
    [-3.67578217, 3.77055619, 0.0],
]

config.frame_width = 18
config.frame_height = 12

class getLSWgeoms(ZoomedScene):
    def construct(self):
        
        # Polygon
        buffer = Polygon(*bufferCoordinates)
        buffer.set_fill(PINK, opacity=0.5)

        # Single Lines
        bufferline1 = Line(*[[5, -1.65180767, 0.0], [3.67578217, -3.77055619, 0.0]])
        bufferline1.save_state()
        bufferline1.generate_target()
        bufferline1.target.move_to(5.0 * RIGHT + 3 * DOWN)

        bufferline2 = Line(*[[3.67578217, -3.77055619, 0.0], [-5.0, 1.65180767, 0.0]])
        bufferline2.save_state()
        bufferline2.generate_target()
        bufferline2.target.move_to(1.5 * DOWN + 1 * LEFT)

        bufferline3 = Line(*[[-5.0, 1.65180767, 0.0], [-3.67578217, 3.77055619, 0.0]])  
        bufferline3.save_state()
        bufferline3.generate_target()
        bufferline3.target.move_to(5 * LEFT + 3 * UP)

        bufferline4 = Line(*[[-3.67578217, 3.77055619, 0.0],[5, -1.65180767, 0.0]])   
        bufferline4.save_state()
        bufferline4.generate_target()
        bufferline4.target.move_to(1.5 * UP + 1 * RIGHT)
        
        # Play Scenes
        self.play(FadeIn(buffer), run_time=1)
        self.play(
            MoveToTarget(bufferline1),
            MoveToTarget(bufferline2),
            MoveToTarget(bufferline3),
            MoveToTarget(bufferline4),
            run_time=3
        )
        self.wait()
        self.play(Restore(bufferline1),Restore(bufferline2),Restore(bufferline3),Restore(bufferline4), )
        self.wait()

    Btw, using the target functions here is a bit more complicated than necessary imo, but maybe this is just because this is mwe. Also, your bufferlines* will appear directly in the scene when they will be moved, they are not created or sth. similar before.

    UPDATE: Here is an answer which is more how I would have done it.

    from manim import *

bufferCoordinates = [
    [5, -1.65180767, 0.0],
    [3.67578217, -3.77055619, 0.0],
    [-5.0, 1.65180767, 0.0],
    [-3.67578217, 3.77055619, 0.0],
    [5, -1.65180767, 0.0],
]

config.frame_width = 18
config.frame_height = 12


class getLSWgeoms(ZoomedScene):
    def construct(self):
        # Polygon
        buffer = Polygon(*bufferCoordinates[:4])
        buffer.set_fill(PINK, opacity=0.5)

        # Single Lines
        bufferlines = VGroup(
            *[
                Line(start, end)
                for start, end in zip(bufferCoordinates[:4], bufferCoordinates[1:])
            ]
        )
        bufferlines.save_state()

        # Play Scenes
        self.play(FadeIn(buffer), run_time=1)
        self.wait()
        self.play(Create(bufferlines))
        self.wait()
        self.play(
            bufferlines[0].animate.move_to(5.0 * RIGHT + 3 * DOWN),
            bufferlines[1].animate.move_to(1.5 * DOWN + 1 * LEFT),
            bufferlines[2].animate.move_to(5 * LEFT + 3 * UP),
            bufferlines[3].animate.move_to(1.5 * UP + 1 * RIGHT),
            run_time=3,
        )
        self.wait()
        self.play(Restore(bufferlines))
        self.wait()

    I'm not a python expert, so the list operations could maybe even more optimized. Instead of animating each bufferline you could also use an AnimationGroup, but I don't use it that often. I think like this it is more readable. Also, you could use shift() instead of move_to() but I was too lazy to do the recalculation :D.