Using the parallel_offset on LineString produces unexpected output

[LuckyLub]

Expected behavior and actual behavior.

I use the parallel offset in a script to render some geometries. But I ran into an edgecase (?) which resulted in an unexpected output, best described by some pictures, see below. Other datasets, produce result I would expect.

Result:

Expectation:

Steps to reproduce the problem.

from shapely.geometry import LineString, JOIN_STYLE

my_line = LineString([(-15600.0, -5400.0), (-14600.0, -5400.0), (-14600.0, -3400.0), (-15600.0, -3400.0)])
my_line.parallel_offset(800, join_style=JOIN_STYLE.mitre)

Operating system

Linux Arch

Shapely version and provenance

Shapely==1.7.1 installed from PyPI using pip

[theroggy]

Seems to have been fixed, as it cannot be reproduced anumore with GEOS 3.14.1.

import matplotlib.pyplot as plt
from shapely.geometry import LineString, JOIN_STYLE
from shapely import plotting as plot

my_line = LineString(
    [(-15600.0, -5400.0), (-14600.0, -5400.0), (-14600.0, -3400.0), (-15600.0, -3400.0)]
)
offset = my_line.parallel_offset(800, join_style=JOIN_STYLE.mitre)

plot.plot_line(my_line)
plot.plot_line(offset, color="red")
plt.show()