Bug summary
Diagonal and box lines are produced by pcolormesh using a cmap with transparency.
Code for reproduction
import matplotlib.colors as m_colors
import matplotlib.pyplot as plt
import numpy as np
plt.pcolormesh(np.array([[0, 1, 2], [0, 1, 2]]),
np.array([[0, 0, 0], [1, 1, 1]]),
np.array([[0, 1, 2], [0, 1, 2]]),
cmap=m_colors.LinearSegmentedColormap.from_list(
"", [(0, 0, 0, 0), (0, 0, 0, 1)]),
shading="gouraud")
plt.plot()
Actual outcome

Expected outcome
No diagonal or box lines should appear.
Additional information
No response
Operating system
No response
Matplotlib Version
3.6.2
Matplotlib Backend
QtAgg
Python version
No response
Jupyter version
No response
Installation
None
Bug summary
Diagonal and box lines are produced by
pcolormeshusing a cmap with transparency.Code for reproduction
Actual outcome
Expected outcome
No diagonal or box lines should appear.
Additional information
No response
Operating system
No response
Matplotlib Version
3.6.2
Matplotlib Backend
QtAgg
Python version
No response
Jupyter version
No response
Installation
None