drawArrays

#include <iostream>
#include <ctime>
#include <SDL.h>
#include <OpenGL/gl.h>

using namespace std;


SDL_Window* win;
Args args;

typedef struct _Args {
    bool debug;
} Args;

typedef struct _Input {
    bool quit;
} Input;

int parse_args(int argc, char** argv, Args* outArgs)
{
    for (int i = 0; i < argc; ++i)
    {
      char* arg = argv[i];
      char first = arg[0];
      if (first == '-')
      {
        if (arg[1] == 'd')
          outArgs->debug = true;
      }
    }

    return 0;
}

Input handle_input()
{
    SDL_Event event;
    Input ret;
    while (SDL_PollEvent(&event) )
    {
        if (event.type == SDL_QUIT) ret.quit = true;
        if (event.type == SDL_KEYDOWN) ret.quit = true;
    }
    return ret;
}
void loop()
{
    // Set up VBO
    const float vertexPositions[] = {
          0.75f, 0.75f, 0.0f, 1.0f,
          0.75f, -0.75f, 0.0f, 1.0f,
          -0.75f, -0.75f, 0.0f, 1.0f,
    };
    GLuint vbo;
    glGenBuffers(1, &vbo);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPositions), vertexPositions, GL_STATIC_DRAW);
    glBindBuffer(GL_ARRAY_BUFFER, 0);

    // TODO init shaders

    // Misc setup
    glViewport(-1, -1, 20, 20);
    glClearColor(0.0f, 1.0f, 1.0f, 0.0f);

    while (true)
    {
        // Input
        Input input = handle_input();
        if (input.quit) break;

        // Clear
        glLoadIdentity();
        glClear(GL_COLOR_BUFFER_BIT);

        // Render
        glColor3f(0, 0, 1.0);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
        glDrawArrays(GL_TRIANGLES, 0, 3);
        glDisableVertexAttribArray(0);

        // Commit
        SDL_GL_SwapWindow(win);

        SDL_Delay(50);
    }
}

void print_info()
{
    SDL_version version;
    SDL_VERSION(&version);
    cout << "SDL version: " << (int)version.major << "." << (int)version.minor << (int)version.patch << endl;
    SDL_GetVersion(&version);
    cout << "runtime version: " << (int)version.major << "." << (int)version.minor << (int)version.patch << endl;
    printf("OpenGL vendor: "  "'%s'\n" , glGetString(GL_VENDOR));
    printf("OpenGL renderer: "  "'%s'\n" , glGetString(GL_RENDERER));
    printf("OpenGL version: "  "'%s'\n" , glGetString(GL_VERSION));
    printf("GLSL version: "  "'%s'\n" , glGetString(GL_SHADING_LANGUAGE_VERSION));
}

int main ( int argc, char** argv )
{
    int ret = parse_args(argc, argv, &args);
    if (ret) return ret;

    srand(time(NULL));

    if (SDL_Init(SDL_INIT_VIDEO) < 0) 
    {
        cerr << "Couldn't init SDL";
        return 1;
    }

    win = SDL_CreateWindow("SDL2/GL4.3", 0, 0, 200, 200, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);    
    if (win == NULL) 
    {
        cerr << "Couldn't set video mode";
        return 2;
    }

    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
    SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
    SDL_GLContext context = SDL_GL_CreateContext(win);
    if (context == NULL)
    {
        cerr << "Couldn't get a gl context: " << SDL_GetError();
        return 3;
    }

    print_info();

    loop();

    SDL_GL_DeleteContext(context);
    SDL_Quit();
    return 0;
}