OpenGL Weirdness

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Try this:

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    dispList = glGenLists(1);

    glNewList(dispList, GL_COMPILE);

    for(int x=-768; x<768; x++)
    for(int y=-768; y<768; y++)
    {
        glBegin(GL_QUADS);
            glColor3f((double)(rand() % 100) / 500,
      (double)(rand() % 100) / 100, 0);
            glVertex3i((x)  * 1, (y)  * 1, 0);
            glVertex3i((x+1)* 1, (y)  * 1, 0);
            glVertex3i((x+1)* 1, (y+1)* 1, 0);
            glVertex3i((x)  * 1, (y+1)* 1, 0);
        glEnd();
    }

    glEndList();

and render your display list. Then, try this:

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    dispList = glGenLists(1);

    glNewList(dispList, GL_COMPILE);
    glBegin(GL_QUADS);    // <- the subtle difference is here

    for(int x=-768; x<768; x++)
    for(int y=-768; y<768; y++)
    {
            glColor3f((double)(rand() % 100) / 500,
      (double)(rand() % 100) / 100, 0);
            glVertex3i((x)  * 1, (y)  * 1, 0);
            glVertex3i((x+1)* 1, (y)  * 1, 0);
            glVertex3i((x+1)* 1, (y+1)* 1, 0);
            glVertex3i((x)  * 1, (y+1)* 1, 0);
    }
    glEnd();        // <- and here

    glEndList();

I don’t know if its my graphics drivers, or graphics card or perhaps just me, but the top code maxed out at 60 fps while the bottom code ran at ~10 fps.

Oh, and don’t ask me why I’m using display lists.

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