matplotlib-devel Mailing List for matplotlib

On Sun, Jul 18, 2010 at 3:35 PM, Benjamin Root <ben...@ou...> wrote:

> On Sun, Jul 18, 2010 at 1:40 PM, Benjamin Root <ben...@ou...> wrote:
>
>> On Sun, Jul 18, 2010 at 12:05 PM, Benjamin Root <ben...@ou...> wrote:
>>
>>>
>>>
>>> On Sun, Jul 18, 2010 at 8:56 AM, João Luís Silva <js...@fc...>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

On Sun, Jul 18, 2010 at 3:33 PM, H Mike Duan <h.m...@gm...> wrote:

> Ben,
>
> > 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.
>
> I think the problem is that mplot3d can't reliably determine which
> parts of the surfaces or lines are in front and which are behind. This
> is especially clear in the test example where the yellow sphere
> doesn't cover parts of the red wire frame. The issue that some objects
> can only be seen at certain angles is likely to be a consequence of
> this bug.
>
> I want to use mplot3d to visualize my simulations. Is it your opinion
> that this bug can't be fixed in a short term? If so, I'll have to
> explore other options. Thanks!
>
> -Mike
>

My guess is yes, this can not be fixed in a short term, but I am very new to
mplot3d, so I don't know for sure.

Ben

On Sun, Jul 18, 2010 at 1:40 PM, Benjamin Root <ben...@ou...> wrote:

> On Sun, Jul 18, 2010 at 12:05 PM, Benjamin Root <ben...@ou...> wrote:
>
>>
>>
>> On Sun, Jul 18, 2010 at 8:56 AM, João Luís Silva <js...@fc...> 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

Ben,

> 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.

I think the problem is that mplot3d can't reliably determine which
parts of the surfaces or lines are in front and which are behind. This
is especially clear in the test example where the yellow sphere
doesn't cover parts of the red wire frame. The issue that some objects
can only be seen at certain angles is likely to be a consequence of
this bug.

I want to use mplot3d to visualize my simulations. Is it your opinion
that this bug can't be fixed in a short term? If so, I'll have to
explore other options. Thanks!

-Mike

On Sun, Jul 18, 2010 at 12:05 PM, Benjamin Root <ben...@ou...> wrote:

>
>
> On Sun, Jul 18, 2010 at 8:56 AM, João Luís Silva <js...@fc...> 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


>
>
>
>>
>> ------------------------------------------------------------------------------
>> This SF.net email is sponsored by Sprint
>> What will you do first with EVO, the first 4G phone?
>> Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
>> _______________________________________________
>> Matplotlib-devel mailing list
>> Mat...@li...
>> https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
>>
>
>

On Sun, Jul 18, 2010 at 8:56 AM, João Luís Silva <js...@fc...> 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



>
> ------------------------------------------------------------------------------
> This SF.net email is sponsored by Sprint
> What will you do first with EVO, the first 4G phone?
> Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
> _______________________________________________
> Matplotlib-devel mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
>

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

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

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

fig = plt.figure()
ax = fig.gca(projection='3d')

u = np.linspace(0, 2 * np.pi, 100)
v = np.linspace(0, np.pi, 100)

x = 10 * np.outer(np.cos(u), np.sin(v))
y = 10 * np.outer(np.sin(u), np.sin(v))
z = 10 * np.outer(np.ones(np.size(u)), np.cos(v))
ax.plot_surface(x, y, z,  rstride=4, cstride=4, color='y', alpha=0.5)
ax.plot_wireframe(x, y, z, rstride=10, cstride=10, color='b')
ax.plot_wireframe(x*1.1, y*1.1, z*1.1, rstride=20, cstride=20, color='r')