void linia1(int x1, int y1, int x2, int y2, Uint8 R, Uint8 G, Uint8 B) {

setPixel(x1, y1, 255, 0, 0);
setPixel(x2, y2, 255, 0, 192);


    int dy = y2;
    int dx = x2;
    int x = 0;
    int y = 0;
    setPixel(x, y, R, G, B);

    //dla górnego kąta 45 stopni
    if(dx > dy){

        while(x < x2){

                x++;
                y=(dy/dx)*x;

            setPixel(x, y, R, G, B);
        }
    }

    //dla dolnego kąta
    else{

        while(y < y2){

                y++;
                x=(dx/dy)*y;

            setPixel(x, y, R, G, 255-B);
        }
    }
    SDL_Flip(screen);
}