Bug report

Bug summary

The marker sizes that specified with s= argument in scatter function are wrong, and even worse, the markers are changing their sizes every time the plot is re-rendered (panning or resizing). It seems that the sizes are randomly reassigned to these markers.

Code for reproduction

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D

fig = plt.figure()

# matplotlib 3.4
ax = Axes3D(fig, auto_add_to_figure=False)
fig.add_axes(ax)
# matplotlib 3.3.4
# Axes3D(fig)

x = np.random.rand(200)
y = np.random.rand(200)
z = np.random.rand(200)
ax.scatter(x, y, z, s=x*50)

plt.show()

Actual outcome

Expected outcome

As shown in the screen recording, the sizes are correct and not changing. matplotlib was 3.3.4 in the following example.

Matplotlib version

• Operating system: Arch Linux
• Matplotlib version (import matplotlib; print(matplotlib.__version__)): 3.4.0
• Matplotlib backend (print(matplotlib.get_backend())): Qt5Agg
• Python version: 3.9.2
• Jupyter version (if applicable): Not using it
• Other libraries: numpy 1.20.1

I installed both python, numpy and matplotlib with pacman package manager from Arch's official repository.