Software Renderer Design

#include <ctime>#include <cstdlib>#include "SDL.h"int * screen_pixels;int screen_width = 640;int screen_height = 480;int screen_bpp = 32;int main(int argc, char ** argv){  if (SDL_Init(SDL_INIT_VIDEO) == -1) { return 1; } //initializes SDL (this should be the first SDL call you do), and if -1, then error occurred  SDL_Surface * screen = SDL_SetVideoMode(screen_width, screen_height, screen_bpp, SDL_SWSURFACE|SDL_DOUBLEBUF); //sets up a window for you, allocated in main memory so you don't have to lock the surface before manipulating the pixels  if (screen == NULL) { SDL_Quit(); return 1; }  screen_pixels = reinterpret_cast<int*>(screen->pixels); //point the screen_pixels pointer to the screen structure's pixels  srand(time(0));  do{    //example of pixel manipulation using the screen_pixels pointer    for (int y = 0; y < screen_height; ++y){      int * dst = screen_pixels +(screen_width*y); //gets y row      for (int x = 0; x < screen_width; ++x){        dst[x] = rand(); //sets pixel color randomly      }    }    SDL_Flip(screen); //updates the contents of the window  }while (!QuitEvent()); //QuitEvent() is just made up  SDL_FreeSurface(screen); //deallocates the screen (do this before calling SDL_Quit)  SDL_Quit(); //closes SDL (this should be the last SDL call you do)  return 0;}

union color32{  unsigned int value;  struct { unsigned char blue, green, red, alpha; } channels;};