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OpenGL Multi-threaded texture problems.

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bluntman    255
In my app I am running a few different threads, all with thier own GL contexts, and lists shared (using wglShareLists) with the main thread. In one thread I am calling glTexImage2D and it is returning GL_INVALID_OPERATION. The only way (according to the MSDN docs anyway) that this can return is if glTexImage2D is called between glBegin and glEnd. I am certain that in its own thread that is not the case, but can other threads interfere with this operation? Also the call is actually working, so whats with the error? I could just ignore it but it probably signifies some deeper problem which will come back to bite me at some point. This is the call:
// enable this texture
glBindTexture(GL_TEXTURE_RECTANGLE_ARB, m_nOpenGLReference);

glTexImage2D(GL_TEXTURE_RECTANGLE_ARB, 0, glformat, 
    image->GetWidth(), image->GetHeight(), 0, gliformat, 
    gltype, image->GetBitsPointer());

// check for errors
err = glGetError();

if(err == GL_INVALID_ENUM)
     m_sLastError = "Cannot create OpenGL "
          "texture, error in OpenGL parameters.";
else if(err == GL_INVALID_VALUE)
     m_sLastError = "Cannot create OpenGL texture"
          ", data is incorrect.";
else if(err == GL_INVALID_OPERATION)
     m_sLastError = "Cannot create OpenGL texture"
          ", called between glBegin and glEnd.";

Also, I create all my texture references in the main thread using the main HGLRC, this is correct right? Thanks!

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bpoint    464
glGetError returns the last error flagged by any function, not just the previously called function. I'm willing to bet that glTexImage2D is not what is returning your GL_INVALID_OPERATION. Put in another glGetError check before calling glTexImage2D, and make sure there's no error carried over from a previous function.

That being said, as long as your contexts are different, there is no reason a different thread would interfere with your GL state and raise spurious errors.

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GamerSg    378
For such problems i would reccommend you use GLIntercept, it helps detects OpenGL errors and even texture/VBO/shader leaks. Also you need not touch your source code.

Also, I create all my texture references in the main thread using the main HGLRC, this is correct right?

I dont use GL in multiple threads so i wouldnt know but i get the feeling that texture references should be created in the thread where it is used.

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