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glGenVertexArrays causes a segmentation fault, how do I properly set up an OpenGL context?

I'm trying to code a simple triangle. However glGenVertexArrays(1, &VertexArrayID) casues a segmentation fault whenever I run it.

SDL_Init(SDL_INIT_VIDEO);

SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);

SDL_Window* window = SDL_CreateWindow("OpenGL", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_OPENGL);
SDL_GLContext context = SDL_GL_CreateContext(window);

SDL_Event event;
SDL_bool quit = SDL_FALSE;

GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID); // This causes crash

I found the exact same thing here OpenGL Segfaults on glGenVertexArrays but

I forgot to setup an OpenGL context. All fixed now.

doesn't help, as I believe I have already created an OpenGL context SDL_GLContext context = SDL_GL_CreateContext(window);.

How do I properly set up an OpenGL context?

Solution

  • You have to Initialize GLEW. Call glewInit immediately after creating the OpenGL context:

    SDL_GLContext context = SDL_GL_CreateContext(window);

if (glewInit() != GLEW_OK)
{
    // error handling
    // [...]
}

    Note, that glewInit will return GLEW_OK f it was successful. glewInit initializes the function pointers for the OpenGL functions. If you try to call the function through an uninitialized function pointer, a segmentation fault occurs.