Fwd: [XForms] OpenGL and Threads- again

Nicolas Castagné nicolas.castagne at imag.fr
Fri Jun 27 14:57:00 EDT 2003

Hi all,

Thx for trying David. I decided to fwd your mail on the mail list (see 
below), since it may be of interest for other.

The behaviour you obtained is somehow the one I get on octane - appart 
the fact SGi octane is a bit slower ;-)

The questions then are :
	1) is multithreading correctly supported by OpenGL in case of 
non-direct rendering ?
	2) if so, where is the fault in my program ?

Wish some of you may answer !

Once again, I would ask those who have already implemented a 
'multithreaded' GL canvas under XForms to test their program with 
non-direct rendering (Canvas's direct field set to 0 or distant 



Début du message réexpédié :

> De: David Scriven <davidwriter at yahoo.com>
> Date: Ven 27 jun 2003  20:42:26 Europe/Paris
> À: "Nicolas_Castagné" <nicolas.castagne at imag.fr>
> Objet: Rép : [XForms] OpenGL and Threads- again
> Hi Nicolas,
> I tried your program on a platform running RedHat 9 with XFree86 4.3.0
> on an NVIDIA Ti 4200 (NVIDIA supply their own drivers and GL libraries)
> 1. With DIRECT = 1 the program ran fine although the rate in the
> left hand window was so fast that the cube was blurred. The rate
> in the right window was much slower.
> 2. With DIRECT = 0 the program still worked, BUT, the program would
> not respond to the buttons once Go! was pressed and the cube on
> the right did not move. In addition, when I covered and then uncovered
> the window, the right hand screen was not redrawn (ie it remained
> black). In addition I got messages like:
> Xlib: unexpected async reply (sequence 0x288ad)!
> 3,. In light of the above I didn't try remote execution.
> I compiled the program with
> gcc ThreadGL.c -o ThreadGL  -I /usr/X11R6/include -O2 -L/usr/X11R6/lib
> -lforms -lformsGL -lpthread -lGL  -lGLU
> using gcc ver 3.2.2
> I'll try and look through your code this weekend if I get a chance.
> DS
> : > To subscribers of the xforms list
>> 	This mail is addressed to those that use OpenGL within XForms.
>> 	I have had no answer concerning my last message, but I really think
>> the subject of threads and openGL is of interest for the XForms
>> community.....
>> 	My aim concerning this question is to add a small demo to the XForms
>> demo programs.
>> 	So, let's play again !
>> -------
>> 	You will find enclosed a short program which implements a GLCanvas
>> drawn by a thread.
>> 	This program is stable with direct rendering. However, it is not
>> stable on my IRIX system in case of rendering through the X sever,
>> especially in case of a distant execution.
>> 	-> Could some of you try to compile this program and run it locally
>> and on a distant machine ? 10 min. work !
>> -------
>> 	The next part of the message is addressed to those who have
>> successfully implemented a GLCanvas drawn by a thread.
>> 	Did you tried non-direct rendering on these canvas ?
>> 	If it runs properly, it would be very helpful if you could have a
>> look
>> to my code and give advices !
>> 	Thx ,
>> 	Nicolas
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