Thanks Guys!

I change a little bit the code (move the code to another function), and now
works... glFlush or glFinish were not required anymore... It is like a VC++
Bug... or might be a side effect....

Cheers
RIX



----- Original Message -----
To: "Multiple recipients of list OPENGL-GAMEDEV-L"
<OPENGL-GAMEDEV-L@...>
Sent: Friday, October 07, 2005 1:04 PM


>
> Hi Rix and Matthäus,
>
>  Evan is right.  If sleep() affects your ReadPixels() result,
> something is probably wrong in the driver. (Unless you're using
> an asynch extension like PDR that requires the app to use fences
> or similar.)
>
>  Perhaps you can contact me offline?
>
> Thanks -
> Cass
>
>> -----Original Message-----
>> From: ml-errors@... [mailto:ml-errors@...] On
>> Behalf Of Evan Hart
>> Sent: Friday, October 07, 2005 10:39 AM
>> To: Multiple recipients of list OPENGL-GAMEDEV-L
>> Subject: RE: GLSL + 6800 + Multiple steps by frame
>>
>>
>>
>> Actually, assuming that the read is done with a normal
>> glReadPixels, neither glFlush nor glFinish are required,
>> because OpenGL commands are guaranteed (to appear) to
>> complete in-order given a single context. It sounds like a
>> driver bug to me, or you are doing something that explicitly
>> allows synchronous operations and not accounting for it.
>>
>>   -Evan
>>
>>
>> -----Original Message-----
>> Sent: Friday, October 07, 2005 3:09 AM
>> To: Multiple recipients of list OPENGL-GAMEDEV-L
>>
>> You need to call glFinish (), not glFlush (). glFlush ()
>> means that all
>> commands are passed to OpenGL for processing - not that the
>> processing
>> has finished (for example, if you use OpenGL via Network, glFlush ()
>> send all commands in a packet). glFinish () on the other hand
>> does wait
>> until the rendering has finished.
>>
>> Cheers
>>
>> Matthäus Chajdas
>>
>> Rhadamés Carmona schrieb:
>> > Hello Everybody
>> >
>> > I am programming with 3D textures and GLSL. At some point, I was
>> > interested
>> > in making 2 renderings in one frame, for comparrison...
>> >
>> > void DrawScene()
>> > {
>> >   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
>> >   Render();
>> >   glFlush();
>> >   ReadFrameBuffer(A);
>> >   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
>> >   Render();
>> >   glFlush();
>> >   ReadFrameBuffer(B);
>> >   difference = B-A;
>> >   // Do something with difference, here!....
>> >   glFlnish();
>> >   glutSwapBuffer();
>> > }
>> >
>> > The second rendering is not correct... I get a mess. But,
>> If I put an
>> > Sleep(200) after every glFluch, everything is ok!.... Coudl
>> you give me any
>> > clue about what the hell is goiing on?
>> >
>> > Cheers Guys!
>> >
>> > Rix
>> >
>> > Note: I am using latest drivers....
>> >
>> > -----
>> > FAQ and OpenGL Resources at:
>> >   http://www.geocities.com/SiliconValley/Hills/9956/OpenGL
>> >
>> -----
>> FAQ and OpenGL Resources at:
>>   http://www.geocities.com/SiliconValley/Hills/9956/OpenGL
>>
>> --
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>>
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> -----
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> --
> Author: Cass Everitt
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--
Author: =?iso-8859-1?Q?Rhadam=E9s_Carmona?=
   INET: rcarmona@...

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