Can't draw with opengl version greater then 3.1 with SDL

Question

I'm making a simple application using OpenGL, GLEW and SDL2 which draws a simple quad on screen (I'm following the example on lazyfoo site with modern OpenGL). When I use opengl version 3.1 everything works fine, but if I use OpenGL version 3.2+ draw commands don't work (triangle doesn't appear). Does someone know what I am doing wrong?

This is how I setup everything:

    if (SDL_Init(SDL_INIT_VIDEO) != 0) {

        return false;
    }
    SDL_GL_SetAttribute(SDL_GL_ACCELERATED_VISUAL, 1);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
m_pWindow = SDL_CreateWindow("Hello World!", 100, 100, 800, 600, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN );
m_pGLContext = SDL_GL_CreateContext(m_pWindow);
    glewExperimental = GL_TRUE;
    GLenum glewError = glewInit();
    if (glewError != GLEW_OK)
    {
        return false;
    }

    //Use Vsync
    if (SDL_GL_SetSwapInterval(1) < 0)
    {
        return false;
    }

If you want to check it grab one-file cpp source from http://lazyfoo.net/tutorials/SDL/51_SDL_and_modern_opengl/index.php (on site bottom), and try to change version of opengl from 3.1 to 3.2.

Answer 1

In OpenGL 3.2, the OpenGL profiles were introduced. The core profile actually removes all of the deprecated functions, which breaks compaitibily with older GL functions. The compatibility profile retains backwards compatibility.

To create "modern" OpenGL context, the extensions like GLX_create_context (Unix/X11) or WGL_create_context (Windows) have to be used (and SDL does that for you internally). Citing these extensions specifications gives the answer to your question:

The attribute name GLX_CONTEXT_PROFILE_MASK_ARB requests an OpenGL context supporting a specific profile of the API. If the GLX_CONTEXT_CORE_PROFILE_BIT_ARB bit is set in the attribute value, then a context implementing the core profile of OpenGL is returned. If the GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB bit is set, then a context implementing the compatibility profile is returned. If the requested OpenGL version is less than 3.2, GLX_CONTEXT_PROFILE_MASK_ARB is ignored and the functionality of the context is determined solely by the requested version.

[...]

The default value for GLX_CONTEXT_PROFILE_MASK_ARB is GLX_CONTEXT_CORE_PROFILE_BIT_ARB. All OpenGL 3.2 implementations are required to implement the core profile, but implementation of the compatibility profile is optional.

SInce you did not explicitely request a compatibility profile (and SDL does neither), you got a core profile, and it seems like your code is invalid in a core profile.

You might try requesting a compaitbility profile by adding the

SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_COMPATIBILITY);

hint before creating the context.

But be warned that this is not universally supported - MacOS generally supports only GL up to 2.1 OR GL >= 3.2 core profile only. THe open source drivers on Linux only support OpenGL >= 3.2 only in core profile, too. So my recommendation is that you actually fix your code and switch to a core profile.