main.cpp

// On linux compile with:
// g++ -std=c++17 main.cpp glad/src/glad.c -I./glad/include -o prog -lSDL2 -ldl
// On windows compile with (if using mingw)
// g++ main.cpp ./glad/src/glad.c -I./glad/include -o prog.exe -lmingw32 -lSDL2main -lSDL2

// C++ Standard Libraries
#include <iostream>

// Third-party library
#include <SDL2/SDL.h>
// Include GLAD
#include <glad/glad.h>

int main(int argc, char* argv[]){

    // Create a window data type
    // This pointer will point to the 
    // window that is allocated from SDL_CreateWindow
    SDL_Window* window=nullptr;

    // Initialize the video subsystem.
    // If it returns less than 1, then an
    // error code will be received.
    if(SDL_Init(SDL_INIT_VIDEO) < 0){
        std::cout << "SDL could not be initialized: " <<
                  SDL_GetError();
    }else{
        std::cout << "SDL video system is ready to go\n";
    }
    // Before we create our window, specify OpenGL version
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
    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_DEPTH_SIZE,24);

    // Request a window to be created for our platform
    // The parameters are for the title, x and y position,
    // and the width and height of the window.
    window = SDL_CreateWindow("C++ SDL2 Window",
            20,
            20,
            640,
            480,
            SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL);

    // OpenGL setup the graphics context
    SDL_GLContext context;
    context = SDL_GL_CreateContext(window);

    // Setup our function pointers
    gladLoadGLLoader(SDL_GL_GetProcAddress);

    // Infinite loop for our application
    bool gameIsRunning = true;
    while(gameIsRunning){
        glViewport(0,0,640,480);

        SDL_Event event;
        // Start our event loop
        while(SDL_PollEvent(&event)){
            // Handle each specific event
            if(event.type == SDL_QUIT){
                gameIsRunning= false;
            }
            if(event.type == SDL_MOUSEMOTION){
                std::cout << "mouse has been moved\n";
            }
            if(event.type == SDL_KEYDOWN){
                std::cout << "a key has been pressed\n";
                if(event.key.keysym.sym == SDLK_0){
                    std::cout << "0 was pressed\n";
                }else{
                    std::cout << "0 was not pressed\n";
                }
            }
            // Retrieve the state of all of the keys
            // Then we can query the scan code of one or more
            // keys at a time
            const Uint8* state = SDL_GetKeyboardState(NULL);
            if(state[SDL_SCANCODE_RIGHT]){
                std::cout << "right arrow key is pressed\n";
            }
        }

        glClearColor(1.0f,0.0f,0.0f,1.0f);
        glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

        SDL_GL_SwapWindow(window);
    }

    // We destroy our window. We are passing in the pointer
    // that points to the memory allocated by the 
    // 'SDL_CreateWindow' function. Remember, this is
    // a 'C-style' API, we don't have destructors.
    SDL_DestroyWindow(window);
    
    // We safely uninitialize SDL2, that is, we are
    // taking down the subsystems here before we exit
    // We add a delay in order to see that our window
    // has successfully popped up.
    SDL_Delay(3000);
    // We add a delay in order to see that our window
    // has successfully popped up.
    SDL_Delay(3000);
    // We add a delay in order to see that our window
    // has successfully popped up.
    SDL_Delay(3000);
    // We add a delay in order to see that our window
    // has successfully popped up.
    SDL_Delay(3000);
    // We add a delay in order to see that our window
    // has successfully popped up.
    SDL_Delay(3000);
    // our program.
    SDL_Quit();
    return 0;
}