Thread: [PyOpenGL-Users] A puzzle regarding running PyOpenGL interactively
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From: Perry G. <pe...@st...> - 2003-02-11 23:07:02
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We have had problems with PyOpenGL for more recent releases of Redhat (e.g., 6.x,7.x, 8.x) that manifest themselves in odd ways. This is the simplest illustration of something that works for some OpenGL implementations and not others. If you start an interactive Python session and types the following sequence of commmands: >>> import OpenGL >>> from OpenGL.GL import * >>> from OpenGL.Tk import * >>> o=Opengl() >>> Exception in Tkinter callback Traceback [...] AttributeError: 'Opengl' instance has no attribute 'redraw' [window turns pink] >>> glClearColor(1,0,0,0) >>> glClear(GL_COLOR_BUFFER_BIT) On some installations, this results in a Tk window appearing, and the last command changes the background color to red. On other installstions, nothing happens with the last command. (Nor does the window turn pink on o=Opengl()). The above will not work for the default installations of OpenGL for Redhat 8 for example (The SGI library apparently). [A natural question is why anyone would run OpenGL in this manner. We use OpenGL to generate plot windows from an interactive command line for a scientific command-line-oriented analysis environment. We do not use it in the usual way of generating a standalone GUI application. The above test illustrates the installations for which the plotting windows are nonfunctional or not] Does anyone understand what it is that causes PyOpenGL to stop working with Python's interactive mode? When we use Mesa instead on Redhat, it works. Unfortunately some users have NVIDIA cards that require the NVIDIA OpenGL library which does not work. We would like to understand what the fundamental problem is and whether there is any solution. Thanks, Perry Greenfield |
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From: <il...@ya...> - 2003-02-11 23:33:52
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I'm not sure about tk; but I use pygame interactively a lot. Maybe you need to call the buffer flip functions, or define a redraw function? In my code I have display objects with start, and stop video method calls. Which basically call pygame.display.init() and pygame.display.quit() ( which opens and closes the display). Then I have a draw method. This all works nicely with nvidia drivers on linux. I get the same behaviour with your tk example. Sorry I'm of not much help. --- Perry Greenfield <pe...@st...> wrote: > We have had problems with PyOpenGL for more recent > releases > of Redhat (e.g., 6.x,7.x, 8.x) that manifest > themselves in odd ways. > This is the simplest illustration of something that > works for > some OpenGL implementations and not others. > > If you start an interactive Python session and types > the following > sequence of commmands: > > >>> import OpenGL > >>> from OpenGL.GL import * > >>> from OpenGL.Tk import * > >>> o=Opengl() > > >>> Exception in Tkinter callback > Traceback > [...] > AttributeError: 'Opengl' instance has no attribute > 'redraw' > [window turns pink] > > >>> glClearColor(1,0,0,0) > >>> glClear(GL_COLOR_BUFFER_BIT) > > On some installations, this results in a Tk window > appearing, and > the last command changes the background color to > red. > On other installstions, nothing happens with the > last command. > (Nor does the window turn pink on o=Opengl()). > The above will not work for the default > installations of OpenGL > for Redhat 8 for example (The SGI library > apparently). > > [A natural question is why anyone would run OpenGL > in this manner. > We use OpenGL to generate plot windows from an > interactive > command line for a scientific command-line-oriented > analysis > environment. We do not use it in the usual way of > generating > a standalone GUI application. The above test > illustrates the > installations for which the plotting windows are > nonfunctional > or not] > > Does anyone understand what it is that causes > PyOpenGL to stop > working with Python's interactive mode? > > When we use Mesa instead on Redhat, it works. > Unfortunately some > users have NVIDIA cards that require the NVIDIA > OpenGL library > which does not work. > > We would like to understand what the fundamental > problem is and > whether there is any solution. > > Thanks, Perry Greenfield > > > > __________________________________________________ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com |
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From: Douglas S. B. <db...@br...> - 2003-02-12 00:27:19
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I have confirmed that Perry's problem listed below is also a problem on my
RedHat 8.0 with an NVIDIA video binary. But I don't think that has too much to
do with the problem (except that I think it is a timing issue).
I think that this is an issue in interactive mode, but only if the system has
time to attempt a redraw before one can assign the o.redraw method. For
example, if I paste the following code all at once into the Python
interpreter, it sometimes works, sometimes doesn't:
def redraw(win = 0):
print win
import OpenGL
from OpenGL.GL import *
from OpenGL.Tk import *
o=Opengl()
o.redraw = redraw
If I pause just a little before the last line, I get the same error.
The solution: I think that OpenGL/Tk/__init__.py should have a default redraw
method that just has a pass, like:
def redraw(self, *dummy):
pass
If this is added, then the error never occurs, because there is a redraw
method now. This also doesn't require a "try" to see if there is a redraw
(that could slow it down), and doesn't seem to have any adverse effects.
Hope that helps,
-Doug
Perry Greenfield <pe...@st...> said:
> We have had problems with PyOpenGL for more recent releases
> of Redhat (e.g., 6.x,7.x, 8.x) that manifest themselves in odd ways.
> This is the simplest illustration of something that works for
> some OpenGL implementations and not others.
>
> If you start an interactive Python session and types the following
> sequence of commmands:
>
> >>> import OpenGL
> >>> from OpenGL.GL import *
> >>> from OpenGL.Tk import *
> >>> o=Opengl()
>
> >>> Exception in Tkinter callback
> Traceback
> [...]
> AttributeError: 'Opengl' instance has no attribute 'redraw'
> [window turns pink]
>
> >>> glClearColor(1,0,0,0)
> >>> glClear(GL_COLOR_BUFFER_BIT)
>
> On some installations, this results in a Tk window appearing, and
> the last command changes the background color to red.
> On other installstions, nothing happens with the last command.
> (Nor does the window turn pink on o=Opengl()).
> The above will not work for the default installations of OpenGL
> for Redhat 8 for example (The SGI library apparently).
>
> [A natural question is why anyone would run OpenGL in this manner.
> We use OpenGL to generate plot windows from an interactive
> command line for a scientific command-line-oriented analysis
> environment. We do not use it in the usual way of generating
> a standalone GUI application. The above test illustrates the
> installations for which the plotting windows are nonfunctional
> or not]
>
> Does anyone understand what it is that causes PyOpenGL to stop
> working with Python's interactive mode?
>
> When we use Mesa instead on Redhat, it works. Unfortunately some
> users have NVIDIA cards that require the NVIDIA OpenGL library
> which does not work.
>
> We would like to understand what the fundamental problem is and
> whether there is any solution.
>
> Thanks, Perry Greenfield
>
>
>
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--
Douglas S. Blank, Assistant Professor
db...@br..., (610)526-6501
Bryn Mawr College, Computer Science Program
101 North Merion Ave, Park Science Building
Bryn Mawr, PA 19010 dangermouse.brynmawr.edu
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