text: //
  //  graphics.h
  //  OHVM
  //  issue at :https://stackoverflow.com/questions/28016258/using-homebrew-installed-sdl2-with-xcode
  //  Created by wwhai on 2020/12/25.
  //
  
  #ifndef graphics_h
  #define graphics_h
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <stdlib.h>
  #include <SDL2/SDL.h>
  #include "SDL2/SDL_ttf.h"
  #define GRAPHICS_WIDTH 640
  #define GRAPHICS_HEIGHT 480
  //
  SDL_Window *main_indow = NULL;
  SDL_Renderer *main_renderer = NULL;
  TTF_Font *font = NULL;
  //
  void init_graphics(SDL_Window *window, SDL_Renderer *renderer);
  //
  void enter_graphics(void);
  //
  void exit_graphics(SDL_Window *window, SDL_Renderer *renderer);
  //
  void points(SDL_Point points[]);
  //
  void lines(SDL_Renderer *renderer, SDL_Point points[]);
  //
  void rectangle(SDL_Renderer *renderer,
                 int x, int y,
                 int w, int h,
                 SDL_bool filled);
  //
  void draw_text(SDL_Renderer *renderer,
                 TTF_Font *font,
                 int x, int y,
                 char text[],
                 int r, int g, int b);
  //
  void refresh_graphics(SDL_Renderer *renderer);
  //
  void clear_graphics(SDL_Renderer *renderer);
  #endif
  /* graphics_h */
  