On Sun, Jul 18, 2010 at 3:35 PM, Benjamin Root <ben.r...@ou.edu> wrote:
> On Sun, Jul 18, 2010 at 1:40 PM, Benjamin Root <ben.r...@ou.edu> wrote:
>
>> On Sun, Jul 18, 2010 at 12:05 PM, Benjamin Root <ben.r...@ou.edu> wrote:
>>
>>>
>>>
>>> On Sun, Jul 18, 2010 at 8:56 AM, João Luís Silva <jsi...@fc.up.pt>wrote:
>>>
>>>> On 07/18/2010 04:58 AM, H Mike Duan wrote:
>>>> > Hi,
>>>> >
>>>> > There seems to be a problem in how 3D surfaces and lines are rendered
>>>> > in mplot3d. The following is a simple script that plots a yellow
>>>> > sphere, a blue wireframe on the surface of the sphere, and a red
>>>> > wireframe outside the sphere. The semi-transparent yellow sphere is
>>>> > rendered beautifully. The blue wireframe can only be seen with certain
>>>> > viewing angles. The red wireframe is seen all the time, but its part
>>>> > that is supposedly behind the sphere appears in front of the sphere.
>>>> > Did I do something wrong or is it a bug of mplot3d? I am using
>>>> > matplotlib 1.0.0 on Mac OS X 10.6. Thanks!
>>>> >
>>>> > -Mike
>>>>
>>>> Additionally the presented example (after adding a plt.show()) will give
>>>> the appended traceback if the sphere is panned around. That won't happen
>>>> if the line
>>>>
>>>> ax = fig.gca(projection='3d')
>>>>
>>>> is replaced with:
>>>>
>>>> ax = Axes3D(fig)
>>>>
>>>> Latest mpl svn (r8565), OS: Debian testing.
>>>>
>>>> Regards,
>>>> João Luís
>>>>
>>>>
>>>>
>>>> Traceback (most recent call last):
>>>> File
>>>>
>>>> "/usr/local/lib/python2.6/dist-packages/matplotlib/backends/backend_gtk.py",
>>>> line 253, in button_release_event
>>>> FigureCanvasBase.button_release_event(self, x, y, event.button,
>>>> guiEvent=event)
>>>> File
>>>> "/usr/local/lib/python2.6/dist-packages/matplotlib/backend_bases.py",
>>>> line 1603, in button_release_event
>>>> self.callbacks.process(s, event)
>>>> File "/usr/local/lib/python2.6/dist-packages/matplotlib/cbook.py",
>>>> line 262, in process
>>>> proxy(*args, **kwargs)
>>>> File "/usr/local/lib/python2.6/dist-packages/matplotlib/cbook.py",
>>>> line 188, in __call__
>>>> return mtd(*args, **kwargs)
>>>> File
>>>> "/usr/local/lib/python2.6/dist-packages/matplotlib/backend_bases.py",
>>>> line 2575, in release_pan
>>>> a.end_pan()
>>>> File "/usr/local/lib/python2.6/dist-packages/matplotlib/axes.py",
>>>> line 2788, in end_pan
>>>> del self._pan_start
>>>> AttributeError: _pan_start
>>>>
>>>>
>>>>
>>> Joao,
>>>
>>> Yes, there is a known issue with objects not properly rendering when
>>> viewed at certain angles. How to go about solving this seems to be a
>>> difficult one to figure out.
>>>
>>> Also, thanks for pointing out the difference between calling gca() and
>>> creating the Axes3D object directly. I am not sure exactly why there would
>>> be a difference, but I will look into it right away.
>>>
>>> Ben Root
>>>
>>
>> Ok, it appears that the .add_subplot() or .gca() approach to creating 3D
>> axes appears to be adding the axes twice to the figure's canvas. Therefore,
>> while the callback to press_pan() is connected only once, the function loops
>> over all the axes in the figure, and connecting end_pan() twice.
>>
>> The end_pan() function deletes _pan_start, so the second subsequent call
>> is trying to delete something that doesn't exist, thereby causing the
>> traceback.
>>
>> So, now the question remains, why is the Axes3D object added twice to the
>> figure?
>>
>> Ben Root
>>
>
> Further investigation reveals that this actually isn't all that unusual.
> If one were to do the same thing, but for a 2d plot, one would find that a
> figure's self.axes list would contain a SubplotAxes object, and a regular
> Axes object. However, in our 3d case, it appears that instead of the
> SubplotAxes object being placed, the regular object is being placed instead.
>
> Hmmm, curiouser, and curiouser...
>
> Ben Root
>
A few corrections. First, I wrong, it is unusual. The second axes that I
noticed in a 2d case came from a colorbar being added. Second, in the 3d
case, it was the Axes3DSubplot object being added twice, not the regular
object like I originally said.
The cause of this is due to the Axes3D initializer adding itself to the
figure object being passed in. This initializer is called when
add_subplot() is called, so add_subplot also adds the axes when it is
finished making it. For normal projections, the initializer does not add
itself to the axes.
Removing the add_axes in the Axes3D initializer would "solve" the issue
outright, however, there are plenty of legacy code where Axes3D is called
with a figure passed in in order to create the axes, and this would break
that use pattern.
Not exactly sure how to proceed here.
Ben Root
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