OpenGL display problems on SGI Fuel

OpenGL display problems on SGI Fuel

Post by netnews.attbi.co » Tue, 21 Jan 2003 07:20:36



I have a 2D graphic program built on SGi irix, using X window, motif, and
openGL. It runs okay on SGI indigo or octane, but it has display problems
running on Fuel with V10 graphic board.The OS is 6.5.15. This problem is
very critical to us.

The problem descriptions:

When the program starts up, or new window initialized, There are always some
garbage windows  (ghosts of previous windows) left on openGl drawing area
(canvas). Resizing, Zooming or Moving window around won't get rid of them.
The garbage window will be gone when you drawing some  objects on the
screen. After that, everything seems back to normal. If you start another
window, same problems will appear again. Our program uses double planes
(normal and overlay), double  buffers and RGB color index. I have tried
several ways to solve this problems, such as clean up buffers when
initializing or resizing, turn off double buffer, use only one plane, none
of them works. It seems glViewport doesn't get set correctly even though the
program passes it correct data.I don't know why.

I like to know what could be the root cause for this problems, why it only
happens on Fuel machine. Any hard ware or software specialties I should look
at? Or any code defect  could cause this kind of machine related problems.
Any suggestions and help would be very appreciated.

Haitong

 
 
 

OpenGL display problems on SGI Fuel

Post by César Blecua Udía » Tue, 21 Jan 2003 08:10:17



> I have a 2D graphic program built on SGi irix, using X window, motif, and
> openGL. It runs okay on SGI indigo or octane, but it has display problems
> running on Fuel with V10 graphic board.The OS is 6.5.15. This problem is
> very critical to us.

> The problem descriptions:

> When the program starts up, or new window initialized, There are always some
> garbage windows  (ghosts of previous windows) left on openGl drawing area
> (canvas).

Do you know whether these "ghosts" are in the normal or in the overlay
planes?

Quote:

[...]

> I like to know what could be the root cause for this problems, why it only
> happens on Fuel machine.

It can be either a bug in your program or a bug in the OS. Some program
bugs are sometimes noticeable on some machines but not in others.

Can you run your program through 'ogldebug' in order to catch errors? If
not, I suggest that you use glGetError() in your rendering loop, in
order to be sure that you're not causing OpenGL errors.

Note that your program can have a graphics bug even if 'ogldebug' and
glGetError() don't catch errors.

Quote:

> Any hardware or software specialties I should look at?

Your OS version is not current, although I don't whether newer versions
have graphics bugfixes for Fuel or not. You may want to try to update,
though.

Btw, if I were you, I'd post also this problem at comp.sys.sgi.graphics,
because you might be able to get more SGI-specific help there.

Csar


 
 
 

OpenGL display problems on SGI Fuel

Post by J Wes » Wed, 22 Jan 2003 12:33:06


Quote:> > When the program starts up, or new window initialized, There are always
some
> > garbage windows  (ghosts of previous windows) left on openGl drawing
area
> > (canvas).

Yeah, happens all the time. The contents of the window are undefined until
you do a glClear() & swapbuffers.
Do it immediately after the window is realized, eg, in the widget's init
callback.

Also, look at GLwNallocateBackground, e.g.,  I don't quite remember what it
does ...

   glxArea = XtVaCreateManagedWidget ("glxArea", glwMDrawingAreaWidgetClass,
          scrolledWindow,
          GLwNdoublebuffer, True,
          GLwNrgba, True,
          GLwNredSize, 4,
          GLwNgreenSize, 4,
          GLwNblueSize, 4,
          GLwNstencilSize, 1,
          GLwNdepthSize, 16,
          GLwNallocateBackground, 1,
          GLwNvisualInfo,visinfo,
          NULL);




> > I have a 2D graphic program built on SGi irix, using X window, motif,
and
> > openGL. It runs okay on SGI indigo or octane, but it has display
problems
> > running on Fuel with V10 graphic board.The OS is 6.5.15. This problem is
> > very critical to us.

> > The problem descriptions:

> > When the program starts up, or new window initialized, There are always
some
> > garbage windows  (ghosts of previous windows) left on openGl drawing
area
> > (canvas).

> Do you know whether these "ghosts" are in the normal or in the overlay
> planes?

> [...]

> > I like to know what could be the root cause for this problems, why it
only
> > happens on Fuel machine.

> It can be either a bug in your program or a bug in the OS. Some program
> bugs are sometimes noticeable on some machines but not in others.

> Can you run your program through 'ogldebug' in order to catch errors? If
> not, I suggest that you use glGetError() in your rendering loop, in
> order to be sure that you're not causing OpenGL errors.

> Note that your program can have a graphics bug even if 'ogldebug' and
> glGetError() don't catch errors.

> > Any hardware or software specialties I should look at?

> Your OS version is not current, although I don't whether newer versions
> have graphics bugfixes for Fuel or not. You may want to try to update,
> though.

> Btw, if I were you, I'd post also this problem at comp.sys.sgi.graphics,
> because you might be able to get more SGI-specific help there.

> Csar


 
 
 

OpenGL display problems on SGI Fuel

Post by César Blecua Udía » Wed, 22 Jan 2003 18:04:44



> > > When the program starts up, or new window initialized, There are always
> some
> > > garbage windows  (ghosts of previous windows) left on openGl drawing
> area
> > > (canvas).

> Yeah, happens all the time. The contents of the window are undefined until
> you do a glClear() & swapbuffers.
> Do it immediately after the window is realized, eg, in the widget's init
> callback.

The OP said that the program runs fine on Indigo2 and Octane (which
should also have "windows ghosts" if he's actually forgetting to
glClear), so I guess that the problem is not caused by lack of glClear()
(moreover, the OP also said that he's clearing buffers at
initialization).

However, without seeing it working nor having more clues from the OP,
it's hard to tell what's causing it (besides, I know of another Fuel
user who apparently is also suffering these "windows ghosts", so I don't
know if it's an OS issue or that both of them are forgetting to do some
important thing at initialization).

Csar

 
 
 

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