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SDL_Render's internal code sets the value of GL_UNPACK_ROW_LENGTH to the number of pixels in a SDL texture when you create or modify one.

SDL makes no guarantees about the OpenGL state for the context it uses for SDL_Render operations outside of internal SDL_Render API calls – using raw OpenGL with SDL_Render is effectively not supported.

I am not using SDL_Render in my code at all. This is the code setting up SDL.

    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
        fprintf(stderr, "Failed to initialize SDL: Error = %s\n", SDL_GetError());
        return -1;
    }

    app.window = SDL_CreateWindow("SDL GL Test",
                                  SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
                                  SCREEN_WIDTH, SCREEN_HEIGHT,
                                  SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN);
    
    if (!app.window) {
        fprintf(stderr, "Failed to create window, error = %s\n", SDL_GetError());
        return -1;
    }

    // Create context
    // Use OpenGL 3.1 core
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 1);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 4);
    
    app.glcontext = SDL_GL_CreateContext(app.window);
    if (app.glcontext == NULL)
    {
        fprintf(stderr, "OpenGL context could not be created! SDL Error: %s\n", SDL_GetError());
    }


Followed by setting up glew

        // Initialize GLEW
        glewExperimental = GL_TRUE;
        GLenum glewError = glewInit();
        if (glewError != GLEW_OK) {
            fprintf(stderr,  "Error initializing GLEW! %s\n", glewGetErrorString(glewError));
        }

This does not reproduce here with SDL 2.0.5 or the latest in revision control, on macOS 10.12.4.

Is it possible GLEW, or something else, changed it?

(we _will_ change it with the Render API, but this attached program does not.)

--ryan.

Created attachment 2743 [details]
test program

Closing this bug, but please reopen it if we can find a way to reproduce it!

Thanks,
--ryan.