Bug: Animating a DashedLine from or to a length of 0 crashes

[trent2]

Description of bug / unexpected behavior

When animating a DashedLine Manim crashes when the the line has a a length of exactly 0.

Expected behavior

The line is either drawn as a point or not at all.

How to reproduce the issue

Code for reproducing the problem

from manim import *

class DashedLineAnimationCrash(Scene):
    def construct(self):
        v = ValueTracker(2)
        l = always_redraw(lambda: DashedLine((0,0,0), (v.get_value(), v.get_value(), 0)))
        # l = always_redraw(lambda: Line((0,0,0), (v.get_value(), v.get_value(), 0))) # would work

        self.add(l)
        self.play(v.animate.set_value(-1))     # <-- no problem since 0 is not exactly produced going from 2 to -1
        self.play(v.animate.set_value(0))  # <-- hits the bug

Additional media files

Logs

Pastebin Logfile

System specifications

System Details

• OS (gentoo Linux 6.12.58-gentoo):
• RAM: 64 GB
• Python version 3.14.0
• Installed modules (provide output from pip list):

Package           Version
----------------- -------
audioop-lts       0.2.2
av                16.1.0
beautifulsoup4    4.14.3
click             8.3.1
cloup             3.0.8
decorator         5.2.1
glcontext         3.0.0
isosurfaces       0.1.2
manim             0.19.2
ManimPango        0.6.1
mapbox_earcut     2.0.0
markdown-it-py    4.0.0
mdurl             0.1.2
moderngl          5.12.0
moderngl-window   3.1.1
networkx          3.6.1
numpy             2.4.2
pillow            12.1.0
pip               26.0.1
pycairo           1.29.0
pydub             0.25.1
pyglet            2.1.13
pyglm             2.8.3
Pygments          2.19.2
rich              14.3.2
scipy             1.17.0
screeninfo        0.8.1
skia-pathops      0.9.1
soupsieve         2.8.3
srt               3.5.3
svgelements       1.9.6
tqdm              4.67.3
typing_extensions 4.15.0
watchdog          6.0.0

LaTeX details

• LaTeX distribution: TeX Live 2025 (bug not related to LaTeX)

Additional comments

See also this reddit post

The bug is also triggered when we start with a length 0 line to animate.

from manim import *

class DashedLineAnimationCrash(Scene):
    def construct(self):
        v = ValueTracker(0)   # <-- initial length 0 
        l = always_redraw(lambda: DashedLine((0,0,0), (v.get_value(), v.get_value(), 0)))

        self.add(l)
        self.play(v.animate.set_value(2))     # <-- now triggered here

[SORVER]

can someone assign this issue to me ? @behackl