[Matplotlib-users] Arc and art3d.pathpatch_2d_to_3d

[Andreas Schneider]

Hi,

I'm trying to plot an arc in a 3d plot using patches.Arc and
art3d.pathpatch_2d_to_3d. However, although the arc is correctly shown
from theta1 to theta2 in a 2d plot, the 3d plot always shows the full
circle. Here is a minimal example:

from matplotlib import pyplot as plt
from matplotlib import patches
from mpl_toolkits.mplot3d import art3d

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
p = patches.Arc((0, 0), 0.5, 0.5, angle=0., theta1=0., theta2=45.)
ax.add_patch(p)
art3d.pathpatch_2d_to_3d(p, z=0, zdir="y")
plt.show()

I get a whole circle but want to have an arc only from 0 degrees to 45
degrees. A corresponding 2d plot shows the arc correctly:

fig = plt.figure()
ax = fig.add_subplot(111)
p = patches.Arc((0, 0), 0.5, 0.5, angle=0., theta1=0., theta2=45.)
ax.add_patch(p)
plt.show()

What am I doing wrong with the conversion from 2d to 3d?

I tried Python 3.7.3 with Matplotlib 3.0.2 and Python 2.7.16 with
Matplotlib 2.2.3 (which are shipped with my Linux distribution).

Thanks in advance for your help.

Andreas