base.cpp

// From  http://sol.gfxile.net/gp/ch02.html
//
// Call with  g++ test.c -o test $(sdl-config --libs --cflags)
// For SDL2 use sdl2-config... below wont work with it though, UpdateRect and SetVideoMode are shunned in SDL 2.0 land
//
#include <stdlib.h>
#if defined(_MSC_VER)
#include "SDL.h"
#else
#include "SDL/SDL.h"
#endif

SDL_Surface *screen;

void putpixel(int x, int y, int color)
{
  unsigned int *ptr = (unsigned int*)screen->pixels;
  int lineoffset = y * (screen->pitch / 4);
  ptr[lineoffset + x] = color;
}

void render()
{   
  // Lock surface if needed
  if (SDL_MUSTLOCK(screen)) 
    if (SDL_LockSurface(screen) < 0) 
      return;

  // Ask SDL for the time in milliseconds
  int tick = SDL_GetTicks();

  // Declare a couple of variables
  int i, j, yofs, ofs;

  // Draw to screen
  // yofs = 0;
  // for (i = 0; i < 480; i++)
  // {
  //   for (j = 0, ofs = yofs; j < 640; j++, ofs++)
  //   {
  //     ((unsigned int*)screen->pixels)[ofs] = i * i + j * j + tick;
  //   }
  //   yofs += screen->pitch / 4;
  // }

  putpixel(10, 10, 0xff0000);
  putpixel(110, 10, 0x00ff00);
  putpixel(10, 110, 0x0000ff);
  //putpixel(11, 11, 0xff0000);
  // Unlock if needed
  if (SDL_MUSTLOCK(screen)) 
    SDL_UnlockSurface(screen);

  // Tell SDL to update the whole screen
  SDL_UpdateRect(screen, 0, 0, 640, 480);    
}


// Entry point
int main(int argc, char *argv[])
{
  // Initialize SDL's subsystems - in this case, only video.
  if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) 
  {
    fprintf(stderr, "Unable to init SDL: %s\n", SDL_GetError());
    exit(1);
  }

  // Register SDL_Quit to be called at exit; makes sure things are
  // cleaned up when we quit.
  atexit(SDL_Quit);
    
  // Attempt to create a 640x480 window with 32bit pixels.
  screen = SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
  
  // If we fail, return error.
  if ( screen == NULL ) 
  {
    fprintf(stderr, "Unable to set 640x480 video: %s\n", SDL_GetError());
    exit(1);
  }

  // Main loop: loop forever.
  while (1)
  {
    // Render stuff
    render();

    // Poll for events, and handle the ones we care about.
    SDL_Event event;
    while (SDL_PollEvent(&event)) 
    {
      switch (event.type) 
      {
      case SDL_KEYDOWN:
        break;
      case SDL_KEYUP:
        // If escape is pressed, return (and thus, quit)
        if (event.key.keysym.sym == SDLK_ESCAPE)
          return 0;
        break;
      case SDL_QUIT:
        return(0);
      }
    }
  }
  return 0;
}