pyopengl-users

[PyOpenGL-Users] get segmentation fault using threading

[Alexandre L. <ale...@gm...>]

Hi.
First : Many thanks for this great python bindings !!

I'm trying to thread my opengl class but it is not working. I get
segmentation fault at glutInit or glutInitDisplayMode

here is the simplest example I was able to build. It never gets to the :
print "end" part.... It seg fault before.

#########################
# code begins here
#########################
from OpenGL.GLUT import *
from threading import *
import time


class GlObject(Thread):

    def __init__(self):
        Thread.__init__(self)

    def run(self):
        print "glutInit"
        glutInit(sys.argv)
        print "initDisplay"
        glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH )
        print "end" # never reach that part...


glObject = GlObject()
print "starting object"
glObject.start()


while True:
    print "waiting"
    time.sleep(1)
##########################

Can any body tell me what I am doing wrong. Is there a way around this ?

I need to get the opengl stuff in a different thread. In my program it is
only a eye candy that print out the state of my algorithm that need to be
running all the time...

please help

thanks all ;)

ªŁ€×

Re: [PyOpenGL-Users] get segmentation fault using threading

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

Alexandre Lacoste wrote:
> Hi.
> First : Many thanks for this great python bindings !!
>
> I'm trying to thread my opengl class but it is not working. I get 
> segmentation fault at glutInit or glutInitDisplayMode
>
> here is the simplest example I was able to build. It never gets to the 
> : print "end" part.... It seg fault before.
Most GUI libraries are inherently single-threaded.  You can often get 
around the problem by *first* importing the GUI library in the GUI 
thread (i.e. *not* in the main thread).  That is, the first time GLUT 
(or wx, or Tk, or any GUI lib I've seen recently) is imported needs to 
be within the GUI thread so that it will create its global state inside 
that thread, rather than the main thread.

The attached version of the code runs fine on my machine.  The only 
change is to move *all* imports of GLUT into the background/GUI thread 
by separating it out into a separate module.  You may want to set up a 
few queues to transfer data  in the call to "run" so that your two 
threads can communicate easily.

HTH,
Mike

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

Re: [PyOpenGL-Users] get segmentation fault using threading

[Alexandre L. <ale...@gm...>]

yess, yess, yessssss !!!!
it's working :D

And this makes so much sense

Thanks for your time Mike.

P.S.: The tool for searching the mailing list archive (on sourceforge)
doesn't work for me... It always return : "PyOpenGL: Searching mail lists
gives *0* results" even if I type a word that is in some mails.


ªŁ€×


On Sun, Sep 21, 2008 at 10:50 AM, Mike C. Fletcher
<mcf...@vr...>wrote:

> Alexandre Lacoste wrote:
>
>> Hi.
>> First : Many thanks for this great python bindings !!
>>
>> I'm trying to thread my opengl class but it is not working. I get
>> segmentation fault at glutInit or glutInitDisplayMode
>>
>> here is the simplest example I was able to build. It never gets to the :
>> print "end" part.... It seg fault before.
>>
> Most GUI libraries are inherently single-threaded.  You can often get
> around the problem by *first* importing the GUI library in the GUI thread
> (i.e. *not* in the main thread).  That is, the first time GLUT (or wx, or
> Tk, or any GUI lib I've seen recently) is imported needs to be within the
> GUI thread so that it will create its global state inside that thread,
> rather than the main thread.
>
> The attached version of the code runs fine on my machine.  The only change
> is to move *all* imports of GLUT into the background/GUI thread by
> separating it out into a separate module.  You may want to set up a few
> queues to transfer data  in the call to "run" so that your two threads can
> communicate easily.
>
> HTH,
> Mike
>
> --
> ________________________________________________
>  Mike C. Fletcher
>  Designer, VR Plumber, Coder
>  http://www.vrplumber.com
>  http://blog.vrplumber.com
>
>