[gameprogrammer] Re: OpenGL + SDL + multi-threading + Theora

["richard sabbarton" <richard.sabbarton@gmail.com>]

Hi There,

 

I ran into similar problem with OpenGL and Multi-Threading.  I was able to generate textures without errors but they never displayed correctly in the application.  I think you run into problems because of the glBegin() and glEnd() in your Main Thread.  You can't manipulate Textures between these (I think from memory) and you cannot guaranty the current status of you main thread when generating the texture.

 

What you could try is decoding the video frames to a Memory Bitmap and then generate the Texture in your main thread from the memory BMP.  Also, you could use a BMP pair and alternate between them for each frame.  You can then set a flag to show which one the main thread should use.  This will avoid errors as you are likely to render each frame a different number of times depending on the speed of your main thread.

 

I have not done this myself but it should be possible.  This was my planned workaround but I never got as far as coding it. My wife had a baby and I haven't looked at a line of code since!  He's two months old now.  Maybe I can start sneaking back to the keyboard while my wife isn't looking...

 

Let me know if it works or if you try it.

 

Rich

 

On 22/08/07, Husam Zakaria <hzcppff@gmail.com> wrote:

Hi, every one

I am working on an application that can play theora ogg file using
OpenGL and SDL, and I looked at the Nebula Device 2 nOggTheoraplayer
class at this link:

http://nebuladevice.cubik.org/documentation/nebula2/classnOggTheoraPlayer.shtml

and build my class the same way they build it, but the problem is that
I don't know how to play the video with such heirarcy.
so I decide to create a thread that decode the video frames and render
the decoded frames to a texture, and in the main thread I will render
this texture to the screen for every frame.

the problem is that I created the texture in the main thread and then
I created the thread that will render to this texture, and when I want
to render to this texture I call the following code to be sure that
the texture has been created:

    assert(glIsTexture(texture_id));

when the application run the assertion will cut the program indecating
that the texture isn't valid, so why does that happend?!! I am sure
that I create the texture in the main thread with the same id, so what
I can do to solve this?

---------------------
To unsubscribe go to http://gameprogrammer.com/mailinglist.html