pyopengl-users — Discussion of all PyOpenGL matters.

[PyOpenGL-Users] Subdivision surface

[duncan d. <dun...@gm...>]

Hello.

I am trying to use the subdivision surface method with PyOpenGL.

Since I am a beginner with 3d graphics and the software I am trying to write
is a port of a hull design software from win32/delphi, I am looking for a
module/library that implement the subdivision surface with pyopengl, or at
least opengl, with, if possible, some example code.

Any hints ?

thanks
Gianluca

Re: [PyOpenGL-Users] OPENGL

[Greg E. <gre...@ca...>]

Mike C. Fletcher wrote:
> The answer is basically that the 
> maintenance headaches outweigh the performance gain (to the extent that 
> the system would likely have been abandoned if we'd kept on with the 
> hand-coded, and then SWIG-coded wrappers).

Have you considered using Pyrex?

> Actually, ctypes is quite slow compared to e.g. SWIG.  That's because it 
> does a lot more work at run-time for every call than a SWIG or similar 
> system does.  OpenGL-ctypes (PyOpenGL) is even slower because it has to 
> provide the array and similar semantics that aren't available in ctypes' 
> core.

This is a little worrying, as OpenGL calls are something you
really don't want being inefficient. I'm hoping this is more
of a theoretical than practical concern. Has anyone done any
measurements?

--
Greg

Re: [PyOpenGL-Users] IDLE, threads and pyopengl

[Shane H. <sha...@ie...>]

ipython is certainly doing this.  I saw the demo at PyCon, and have  
been using it to great effect in debugging and interacting with my wx  
app.

 > ipython -wthread

Works for wxPython guis.  --help gives more options and a bit more  
insight into it.  I'd have a look at what they did to see if it will  
work for you as is, or for your own cmd-based interactive app.

-Shane

On Mar 12, 2007, at 10:37 PM, Mike C. Fletcher wrote:

> JoN wrote:
>> And then he realizes he's asked the completely wrong question.
>>
>> What I meant to ask was:
>>
>> Can IDLE - or any python command interpreter for that matter? - be  
>> run itself as
>> a pythread ?
>>
> There have been systems that used Idle connected up to a GUI with
> PyOpenGL running in it.  I seem to recall systems with IPython and  
> a Tk
> OpenGL GUI as well.  I haven't done it myself, nor do I know if they
> actually used threads.  Normally what happens is that you need to
> arrange to have two event loops running.  Some GUIs (wxPython, for
> instance) can handle that using threads as long as you make sure that
> your first import of wxPython is in the secondary thread (IIRC).
> Running an interpreter thread using cmd should allow you to run  
> that in
> a background thread and let the GUI use the main thread AFAICS.
>
> I code my own systems using something like the wxPython shell widget
> hooked up to a wxPython GUI, so the system all runs in the same  
> thread,
> but that has its own challenges when you want a user to code (e.g.  
> they
> want to time.sleep() in a script).
>
> HTH,
> Mike

Re: [PyOpenGL-Users] IDLE, threads and pyopengl

[Mike C. F. <mcf...@vr...>]

JoN wrote:
> And then he realizes he's asked the completely wrong question.
>
> What I meant to ask was:
>
> Can IDLE - or any python command interpreter for that matter? - be run itself as
> a pythread ?
>   
There have been systems that used Idle connected up to a GUI with 
PyOpenGL running in it.  I seem to recall systems with IPython and a Tk 
OpenGL GUI as well.  I haven't done it myself, nor do I know if they 
actually used threads.  Normally what happens is that you need to 
arrange to have two event loops running.  Some GUIs (wxPython, for 
instance) can handle that using threads as long as you make sure that 
your first import of wxPython is in the secondary thread (IIRC).  
Running an interpreter thread using cmd should allow you to run that in 
a background thread and let the GUI use the main thread AFAICS.

I code my own systems using something like the wxPython shell widget 
hooked up to a wxPython GUI, so the system all runs in the same thread, 
but that has its own challenges when you want a user to code (e.g. they 
want to time.sleep() in a script).

HTH,
Mike

-- 
________________________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com

Re: [PyOpenGL-Users] OPENGL

[Mike C. F. <mcf...@vr...>]

JoN wrote:
> Quoting Jason Ward <ir...@gm...>:
>
>   
>> Python is extensible with C++.
>> So why not just take the gl.h glu.h and friends
>> and mod them so python can call them?
>>     
>
> Isn't that exactly what PyOpenGL does?
>   
It's sort-of what PyOpenGL does.  I believe Jason was asking why we 
don't use C directly to gain speed.  The answer is basically that the 
maintenance headaches outweigh the performance gain (to the extent that 
the system would likely have been abandoned if we'd kept on with the 
hand-coded, and then SWIG-coded wrappers).
>> wouldn't this be faster than your wrapper around ctypes?
>>     
>
> Its hard to imagine anything faster than ctypes, as it binds calls directly to
> the binary code in the .so/.dll's 
>   
Actually, ctypes is quite slow compared to e.g. SWIG.  That's because it 
does a lot more work at run-time for every call than a SWIG or similar 
system does.  OpenGL-ctypes (PyOpenGL) is even slower because it has to 
provide the array and similar semantics that aren't available in ctypes' 
core.

Have fun,
Mike

-- 
________________________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com

Re: [PyOpenGL-Users] IDLE, threads and pyopengl

[JoN <jo...@we...>]

Actually the 'cmd' module seems to fit the bill.
Anybody had experience running it as a thread?

http://docs.python.org/lib/module-cmd.html

Jon


Quoting JoN <jo...@we...>:

> 
> And then he realizes he's asked the completely wrong question.
> 
> What I meant to ask was:
> 
> Can IDLE - or any python command interpreter for that matter? - be run itself
> as
> a pythread ?
> 
> I have a threaded environment.  It would be really nice if I could pretend to
> be
> just another thread and do my locking and unlocking etc as that thread, in
> the
> course of development.
> 
> (Of course not all modules in python are pythread-safe, but I've factored
> that
> in as the threaded environment I'm using makes almost no standard module
> calls,
> and the rest I can deal with case-by-case).
> 
> Jon
> 
> 
> Quoting JoN <jo...@we...>:
> 
> > 
> > Under Linux.
> > 
> > Ok this is really strictly a python question, but its in an opengl context
> > (sic), so I thought I'd start here.  I'll find some python lists to ask as
> > well.
> > 
> > I have an environment under design that drives pyopengl but there is a lot
> > of
> > threaded stuff going on using python threads.  Part of it is a 3d editor
> > (yes
> > yes I know there are good ones already, its just the data model this one
> uses
> > is
> > for solid rendering and i need some custom code).
> > 
> > Now ideally whilst building the editor I'd be able to run IDLE in one X
> > window
> > and have the GL output in another X window (albeit via MESA, but thats
> good
> > enough for debugging).
> > 
> > Question is, can I safely launch threads from inside IDLE?
> > 
> > That's it, that's my Q!
> > 
> > Jon
> > 
> > 
> > 
> > 
> > 
> > 
> > --------------------------------------------------------------------
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> > 
> > 
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> > _______________________________________________
> > PyOpenGL Homepage
> > http://pyopengl.sourceforge.net
> > _______________________________________________
> > PyOpenGL-Users mailing list
> > PyO...@li...
> > https://lists.sourceforge.net/lists/listinfo/pyopengl-users
> > 
> 
> 
> 
> 
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Re: [PyOpenGL-Users] IDLE, threads and pyopengl

[JoN <jo...@we...>]

And then he realizes he's asked the completely wrong question.

What I meant to ask was:

Can IDLE - or any python command interpreter for that matter? - be run itself as
a pythread ?

I have a threaded environment.  It would be really nice if I could pretend to be
just another thread and do my locking and unlocking etc as that thread, in the
course of development.

(Of course not all modules in python are pythread-safe, but I've factored that
in as the threaded environment I'm using makes almost no standard module calls,
and the rest I can deal with case-by-case).

Jon


Quoting JoN <jo...@we...>:

> 
> Under Linux.
> 
> Ok this is really strictly a python question, but its in an opengl context
> (sic), so I thought I'd start here.  I'll find some python lists to ask as
> well.
> 
> I have an environment under design that drives pyopengl but there is a lot
> of
> threaded stuff going on using python threads.  Part of it is a 3d editor
> (yes
> yes I know there are good ones already, its just the data model this one uses
> is
> for solid rendering and i need some custom code).
> 
> Now ideally whilst building the editor I'd be able to run IDLE in one X
> window
> and have the GL output in another X window (albeit via MESA, but thats good
> enough for debugging).
> 
> Question is, can I safely launch threads from inside IDLE?
> 
> That's it, that's my Q!
> 
> Jon
> 
> 
> 
> 
> 
> 
> --------------------------------------------------------------------
> Come and visit Web Prophets Website at http://www.webprophets.net.au
> 
> 
> -------------------------------------------------------------------------
> Take Surveys. Earn Cash. Influence the Future of IT
> Join SourceForge.net's Techsay panel and you'll get the chance to share your
> opinions on IT & business topics through brief surveys-and earn cash
> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
> _______________________________________________
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> http://pyopengl.sourceforge.net
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> PyO...@li...
> https://lists.sourceforge.net/lists/listinfo/pyopengl-users
> 




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Re: [PyOpenGL-Users] OPENGL

[JoN <jo...@we...>]

Quoting Jason Ward <ir...@gm...>:

> Python is extensible with C++.
> So why not just take the gl.h glu.h and friends
> and mod them so python can call them?

Isn't that exactly what PyOpenGL does?

> wouldn't this be faster than your wrapper around ctypes?
> 

Its hard to imagine anything faster than ctypes, as it binds calls directly to
the binary code in the .so/.dll's 



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[PyOpenGL-Users] OPENGL

[Jason W. <ir...@gm...>]

Python is extensible with C++.
So why not just take the gl.h glu.h and friends
and mod them so python can call them?
wouldn't this be faster than your wrapper around ctypes?

[PyOpenGL-Users] Low traffic on this list?

[JoN <jo...@we...>]

By the way, has the traffic on this list dropped dramatically or are my mail
filter rules up the duff?

I seem to only have 21 messages stored since 12 feb 2007.

Jon


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[PyOpenGL-Users] IDLE, threads and pyopengl

[JoN <jo...@we...>]

Under Linux.

Ok this is really strictly a python question, but its in an opengl context
(sic), so I thought I'd start here.  I'll find some python lists to ask as well.

I have an environment under design that drives pyopengl but there is a lot of
threaded stuff going on using python threads.  Part of it is a 3d editor (yes
yes I know there are good ones already, its just the data model this one uses is
for solid rendering and i need some custom code).

Now ideally whilst building the editor I'd be able to run IDLE in one X window
and have the GL output in another X window (albeit via MESA, but thats good
enough for debugging).

Question is, can I safely launch threads from inside IDLE?

That's it, that's my Q!

Jon






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[PyOpenGL-Users] Vertex Buffer Objects

[J. A. <ja...@ca...>]

I've been fiddling around trying to get the Nehe example code for lesson 45 
working with PyOpenGl 3.xxx, however I can't seem to work out how to get it 
to work - I keep getting memory read errors.

Has anybody managed to get VBOs working? Any pointers? Example code?

Thanks,

Jeremy Appleyard

Re: [PyOpenGL-Users] software render

[JoN <jo...@we...>]

Hi Andrew

I think if you use MESA everything is in software.

However, how you install and setup (and specify) Mesa would depend on your OS
and available packages.  There my knowledge runs out sorry.

Jon


Quoting Andrew Wilson <and...@al...>:

> Hello,
>   Is it possible to force opengl to switch from a hardware render mode to a
> software render mode.  For example, I have some code that won't work on some
> older hardware as some of the calls are to functions that aren't supported
> on that card.  Is there a software driver that I can use in those cases
> without much recoding?
>   Thanks
>   Andrew
> 




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[PyOpenGL-Users] GLError( err=1282, description='invalid operation', baseOperation = glNewList, cArguments = (298L, GL_COMPILE))

[Achim D. <do...@pr...>]

Hi,

I'm developing a wx app which uses OpenGL. I updated python to version 
2.5 and have installed PyOpenGL-3.0.0a5-py2.5.egg via easy_install. If I 
execute my app with python 2.5 I get the following error:


   File "E:\Diplom2\displaylists.py", line 14, in field_arrow
     glNewList(name,GL_COMPILE)
   File 
"c:\python25\lib\site-packages\PyOpenGL-3.0.0a5-py2.5.egg\OpenGL\error.py
", line 188, in glCheckError
     baseOperation = baseOperation,
OpenGL.error.GLError: GLError(
         err = 1282,
         description = 'invalid operation',
         baseOperation = glNewList,
         cArguments = (298L, GL_COMPILE)


Any hint what's going on!

regards,
Achim

[PyOpenGL-Users] software render

[Andrew W. <and...@al...>]

Hello,
  Is it possible to force opengl to switch from a hardware render mode to a
software render mode.  For example, I have some code that won't work on some
older hardware as some of the calls are to functions that aren't supported
on that card.  Is there a software driver that I can use in those cases
without much recoding?
  Thanks
  Andrew

[PyOpenGL-Users] Documentation on versioning?

[James H. <jam...@no...>]

Hi All,

I've spent a reasonable amount of time searching for this information before
e-mailing the list, but I'm really not finding what I'm looking for.

I am doing some project planning and am wondering if could someone point me
in the direction as to where I may find pyopengl versioning information. 
I.e. I'd like to know which versions of pyopengl support which GL/GLU/etc.
API versions, what version of python are required for each, etc.  I would
expect this to be in the PKG-INFO or README files, but I'm not finding
anything.

Any help that you can offer would be appreciated.

~James Hiebert

Re: [PyOpenGL-Users] Q: example for offscreen rendering?

[<con...@ce...>]

> What would help me maximally is an example of how to init, render and
> readback sth from an offscreen buffer of any kind.
>

you can use an fbo, here is  an example, hope this helps.
Regards.

=EF=BF=BC
--
St=C3=A9phane Conversy
Ecole Nationale de l'Aviation Civile, Toulouse, France
http://www.tls.cena.fr/~conversy
enac: +33 5 62 17 40 19
dgac r&d: +33 5 62 25 96 48

[PyOpenGL-Users] Bezier curves, anyone?

[Amy L. <al...@ms...>]

Hi,

=20

I'm currently working on implementing a program for Free-Form =
Deformation
using Bezier curves.  I *think* I have all of the pieces that I need to =
get
this program functioning, but I'm definitely missing something.  =
Basically
everything that is drawn to the screen is done so based on a given input
mesh (say an airfoil).  Then, from this airfoil, a bounding box is =
found,
and a list of control points is generated.  Then these control points =
are
used to create a Bezier-based lattice. =20

=20

Now my problem is that I'm not sure when/where to draw the control =
points so
that they are seen as separate entities that still tie in to the Bezier
surface.  And, I'm not sure how to go about manipulating these points =
with
my mouse.=20

=20

BTW, I'm a newbie to both Python and OpenGL. what I've learned in the =
past 6
months, I've taught myself. :0)

=20

Thanks,

Amy

[PyOpenGL-Users] how to use array with glsl ?

[<con...@ce...>]

Hello,

is there a new way to use arrays, or is the following a bug.

this code used to work with pyopengl2:

                 kernel =3D [
                     1, 4, 7, 4, 1,
                     4, 16, 26, 16, 4,
                     7, 26, 41, 26, 7,
                     4, 16, 26, 16, 4,
                     1, 4, 7, 4, 1,
                     ])
                 for i in range(0,boxsize):
                     kernel[i] /=3D 273.
                 glUniform1fvARB(loc, boxsize, kernel)

but with opengl-ctypes I get:

ValueError: ('Expected 1 item array, got 25 item array', array=20
([ 0.003663  ,  0.01465201,  0.02564103,  0.01465201,  0.003663  ,
         0.01465201,  0.05860806,  0.0952381 ,  0.05860806,  0.01465201,
         0.02564103,  0.0952381 ,  0.15018316,  0.0952381 ,  0.02564103,
         0.01465201,  0.05860806,  0.0952381 ,  0.05860806,  0.01465201,
         0.003663  ,  0.01465201,  0.02564103,  0.01465201,  =20
0.003663  ], dtype=3Dfloat32))

I join the increminated program.
This is on MacOSX 10.4, python 2.5, last opengl-ctypes.

best regards,


=EF=BF=BC
--
St=C3=A9phane Conversy
Ecole Nationale de l'Aviation Civile, Toulouse, France
http://www.tls.cena.fr/~conversy
enac: +33 5 62 17 40 19
dgac r&d: +33 5 62 25 96 48

[PyOpenGL-Users] How do I get off?

[Jason W. <ir...@gm...>]

I want to get off this list. How do I unsubscribe

Re: [PyOpenGL-Users] Ctypes work on any DLL?

[Mike C. F. <mcf...@vr...>]

Jason Ward wrote:
> Will ctypes work on any dll. ie One that is not written in C or C++?
>  
> Like will I be able to write a DLL in assembler and ctypes can still 
> read it.
I believe you need to use the "C" calling convention in your interfaces 
(i.e. extern C or whatever the equivalent is in assembler).  Haven't 
done enough assembler to know what that would involve in coding your 
DLL.  ctypes doesn't AFAIK work with C++-coded DLLs unless they happen 
to provide a C interface... and I'm not even sure it would work then 
(name mangling might cause problems).

Probably better to ask on ctypes-users than PyOpenGL-users for this kind 
of question, probably only 5 or 6 of us here use ctypes directly, after all.

Good luck,
Mike

-- 
________________________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com

[PyOpenGL-Users] Ctypes work on any DLL?

[Jason W. <ir...@gm...>]

Will ctypes work on any dll. ie One that is not written in C or C++?

Like will I be able to write a DLL in assembler and ctypes can still read
it.

[PyOpenGL-Users] problems with tesselation w/Python 2.5?

[Maciej K. <mka...@gm...>]

Hi,

I seem to be having trouble with tesselation on my system.

When I run "python tests\test_tess.py", I get this:

begin (4L,)
vertex ((0, 0, 0),)
vertex ((1, 0, 0),)
vertex ((1, 1, 0),)
end ()
error 10397856
Traceback (most recent call last):
  File "test_tess.py", line 38, in <module>
    gluTessEndPolygon(tobj);
WindowsError: exception code 0x9ea8a0

My own code likewise suffers from the mysterious error# and
WindowsError exceptions.  Is this a known issue?  Does a workaround
exist?

Specs of my setup:
- Windows XP SP2
- Python 2.5
- PyOpenGL:  PyOpenGL-3.0.0a5-py2.5.egg

Python exact version:
Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit
(Intel)] on win32

-- 
Maciej Kalisiak
mac [at] dgp.toronto.edu
http://www.dgp.toronto.edu/~mac

Re: [PyOpenGL-Users] glEnable(GL_POLYGON_SMOOTH)

[Mike C. F. <mcf...@vr...>]

Jason Ward wrote:
> I used this and it makes lines across my quad or any other shape for 
> that matter.
>  
> glEnable(GL_POLYGON_SMOOTH)
>  
> I tested it as well in my asm versions of NeHe tuts and it doesn't do 
> this.
> It must be a PyOpenGL bug.
It could be, I suppose.  I'm a bit surprised to see a bug in such a 
well-used function (glEnable being one of the more common functions in 
OpenGL).  Do you have a test case I can run to demonstrate the error?  I 
get very little time to work on PyOpenGL and having a read-made 
test-case makes it far more likely I can track down the problem.

Have fun,
Mike

-- 
________________________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com

[PyOpenGL-Users] glEnable(GL_POLYGON_SMOOTH)

[Jason W. <ir...@gm...>]

I used this and it makes lines across my quad or any other shape for that
matter.

glEnable(GL_POLYGON_SMOOTH)

I tested it as well in my asm versions of NeHe tuts and it doesn't do this.
It must be a PyOpenGL bug.