SDL2

#include <iostream>
#include <math.h>
#include <stdlib.h>
#include "SDL2/SDL.h"
#include "SDL2/SDL_image.h"
using std::cerr;
using std::endl;
using std::string;

bool sRunning;

bool sLoop(); //sLoop handles events and returns "true" if the program should run another frame.
void sInit(); //initializes the screen
void sHandleEvents(); //modify to handle events
void sSync(); //flip the screen
void sQuit(); //uninitialize screen resources

const int scwidth=640;
const int scheight=480;

SDL_Window* gWindow=NULL;
SDL_Renderer *gRenderer = NULL;


SDL_Texture* loadTexture( string path )
{
    //The final optimized image
    SDL_Texture* newTexture = NULL;

    //Load image at specified path
    SDL_Surface* loadedSurface = IMG_Load( path.c_str() );
    if( loadedSurface == NULL )
    {
        cerr<<"Unable to load image "<<path<<". Error: "<<IMG_GetError()<<endl;
        return NULL;
    }

    newTexture = SDL_CreateTextureFromSurface( gRenderer, loadedSurface);
    if( newTexture == NULL )
    {
        cerr<<"Unable to create texture from image "<<path<<". Error: "<<SDL_GetError()<<endl;
    }

    //Get rid of old loaded surface
    SDL_FreeSurface( loadedSurface );

    return newTexture;
}



int main(int argc, char** argv)
{
    sInit();

    SDL_Texture *myTexture=loadTexture("viewport.png");
    SDL_Rect v1={scwidth/2,0,scwidth/2,scheight/2};
    SDL_Rect v2={0,scheight/2,scwidth,scheight/2};
    SDL_Rect v0={0,0,scwidth/2,scheight/2};

    while(sLoop())
    {
        SDL_RenderClear( gRenderer );
        SDL_RenderSetViewport(gRenderer,&v0);
        SDL_RenderCopy( gRenderer, myTexture, NULL, NULL );
        SDL_RenderSetViewport(gRenderer,&v1);
        SDL_RenderCopy( gRenderer, myTexture, NULL, NULL );
        SDL_RenderSetViewport(gRenderer,&v2);
        SDL_RenderCopy( gRenderer, myTexture, NULL, NULL );
        sSync();
    }
    SDL_DestroyTexture(myTexture);
    myTexture=NULL;
    sQuit();
    return 0;
}
bool sLoop()
{
    sHandleEvents();
    return sRunning;
}
void sInit()
{
    sRunning=true;
    if(SDL_Init(SDL_INIT_VIDEO)<0){
        cerr<<"Video initialization failed: "<<SDL_GetError()<<endl;
        sRunning=false;
        return;
    }
    gWindow=SDL_CreateWindow("SDL Tutorial",
        SDL_WINDOWPOS_UNDEFINED,SDL_WINDOWPOS_UNDEFINED,
        scwidth,scheight,SDL_WINDOW_SHOWN);
    if(gWindow==NULL){
        cerr<<"Window creation failed: "<<SDL_GetError()<<endl;
        sRunning=false;
        return;
    }

    gRenderer=SDL_CreateRenderer(gWindow,-1,SDL_RENDERER_ACCELERATED);
    if(gRenderer==NULL){
        cerr<<"Renderer Creation Failed: "<<SDL_GetError()<<endl;
        sRunning=false;
        return;
    }
    SDL_SetRenderDrawColor( gRenderer, 0xFF, 0xFF, 0xFF, 0xFF );

    int imgFlags=IMG_INIT_PNG;
    if(!(IMG_Init(imgFlags)&imgFlags)){
        cerr<<"SDL_image initialization failed. "<<IMG_GetError<<endl;
        sRunning=false;
        return;
    }

}

void sHandleEvents()
{
    SDL_Event e;
    while(SDL_PollEvent(&e))
    {
        switch(e.type)
        {
            case SDL_QUIT:
                sRunning=false;
                break;
            case SDL_KEYDOWN:
                switch(e.key.keysym.sym)
                {
                    case SDLK_ESCAPE:
                        sRunning=false;
                        break;
                    default:
                        break;
                }
                break;
            default:
                break;
        }
    }
}
void sSync(){
    //Update screen
    SDL_RenderPresent( gRenderer );
}
void sQuit()
{
    SDL_DestroyWindow(gWindow);
    gWindow=NULL;
    SDL_Quit();
}