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mplot3d failed to clip bar charts if zlim is set. #8902
Description
Bug report
Bug summary
mplot3d failed to clip bar charts if zlim is set.
Code for reproduction
# Adapter from http://matplotlib.org/2.0.2/examples/mplot3d/bars3d_demo.html
from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
for c, z in zip(['r', 'g', 'b', 'y'], [30, 20, 10, 0]):
xs = np.arange(20)
ys = np.random.rand(20)
# You can provide either a single color or an array. To demonstrate this,
# the first bar of each set will be colored cyan.
cs = [c] * len(xs)
cs[0] = 'c'
ax.bar(xs, ys, zs=z, zdir='y', color=cs, alpha=0.8)
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')
# Set zlim3d
ax.set_zlim3d(bottom=0.2, top=1)
plt.show()Actual outcome
Expected outcome
The z-axis would be clipped according to the zlim_3d parameters properly
Matplotlib version
- Operating System: Windows 10 1703
- Matplotlib Version: 2.0.2
- Python Version: 3.6
- Jupyter Version (if applicable):
- Other Libraries:
Matplotlib installed from pip.
Activity
tacaswell commentedon Jul 17, 2017
To my understanding we do not compute any sort of 3D intersections or have a proper z-buffer (either of which could be used to implement this) and both of which would be pretty major efforts to implement.
@a113n are you interested in working on this?
a113n commentedon Jul 18, 2017
@tacaswell instead of implementing code to compute 3D intersections or z-buffer, could zlim_3d clip the data properly just like the workaround below?
Result:
tacaswell commentedon Jul 20, 2017
That works for this case where you know the shift and use it to both adjust the data and the tick labels. However I don't see how to generalize it.
It would also be odd if it only worked in the z-direction, not x and y.
QuLogic commentedon Jun 23, 2018
The code passes
zdir='y'which is why the layering is in the y direction instead of z.github-actions commentedon Oct 9, 2023
This issue has been marked "inactive" because it has been 365 days since the last comment. If this issue is still present in recent Matplotlib releases, or the feature request is still wanted, please leave a comment and this label will be removed. If there are no updates in another 30 days, this issue will be automatically closed, but you are free to re-open or create a new issue if needed. We value issue reports, and this procedure is meant to help us resurface and prioritize issues that have not been addressed yet, not make them disappear. Thanks for your help!
scottshambaugh commentedon Nov 28, 2023
There is some discussion about this desired behavior in #25804
#27349 will implement option B from the graphic below, but option C is really the thrust of the original question here.
Unfortunately, implementing that would require a huge rewrite of the 3D renderer to do proper culling with a z-buffer or 3D intersections, as @tacaswell mentioned in his comment. I don't think there's anyone able to do that right now, though if someone wants to take it on as a project it'd be awesome.