ASCII Raycasting

ascii-raycasting.c

#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include <math.h>

int quit = 0;
/*int screen_width = 640, screen_height = 480, screen_bpp = 32;*/
int screen_width = 1280, screen_height = 720, screen_bpp = 32;

int char_width = 8, char_height = 12;
int text_width = 80;
int text_height = 40;

SDL_Surface * screen = NULL;
SDL_Surface * characters = NULL;
SDL_Surface * world_map = NULL;
SDL_Event event;

#define PI 3.1415926535897932384626
#define MAX(x, y) (x > y) ? x : y

void apply_surface(int x, int y, SDL_Surface * source, SDL_Surface * destination, SDL_Rect * clip)
{
  SDL_Rect offset;
    
  offset.x = x;
  offset.y = y;
    
  SDL_BlitSurface(source, clip, destination, &offset);
}

Uint32 getpixel(SDL_Surface * surface, int x, int y)
{
    Uint32 * pixels = (Uint32 *)surface->pixels;
    
    return pixels[(y * surface->w) + x];
}

void draw_char(SDL_Rect r, Uint32 color, int x, int y)
{
  int i, j;

  Uint32 * pixels = (Uint32 *)screen->pixels;

  for(i = 0; i < char_height; i++)
    {
      for(j = 0; j < char_width; j++)
	{
	  Uint32 pixel = getpixel(characters, r.x + j, r.y + i);

	  if(pixel == 0xFFFFFF)
	    pixels[((y + i) * screen->w) + (x + j)] = color;
	}
    }
}

void draw_text(unsigned char * text)
{
  SDL_Rect r2 = {0, 0, 8, 12};
  int i, j;

  for(i = 0; i < text_height; i++)
    {
      for(j = 0; j < text_width; j++)
	{
	  r2.x = (text[i * text_width + j] % 16) * char_width;
	  r2.y = (text[i * text_width + j] / 16) * char_height;
	  
	  /*SDL_FillRect(screen, &r, 0xFF << (text[i * text_width + j] * 8));*/
	  /*apply_surface(r.x, r.y, characters, screen, &r2);*/
	  draw_char(r2, (text[i * text_width + j] == 247) ? 0xFF : ((text[i * text_width + j] == '#') ? 0xFF00: 0xFFFFFF), j * char_width, i * char_height);
	}
    }
}

/* ----------------------- IMPORTANT PART ------------------ */
double camera_x, camera_y, camera_rot;

int raycast(int x, int y)
{
  int rt = 0;
  double lx = 1, ly = 0, lz = 0, ll;
  double cx = 8 - camera_x, cy = camera_y, cz = 0;
  double r = 4;
  double lc, cc;
  double br, d, lat;
  int mx, my;

  double step = 0.1 / (text_width / 2.);

  ly = (x - (text_width / 2.)) * step;
  lz = (y - (text_width / 2.)) * step;

  ll = sqrt(lx * lx + ly * ly + lz * lz);

  lx /= ll;
  ly /= ll;
  lz /= ll;

  lc = (cx * lx) + (cy * ly) + (cz * lz);
  cc = (cx * cx) + (cy * cy) + (cz * cz);


  br = (lc * lc) - cc + (r * r);
  if(br < 0)
    return 0;

  d = lc - sqrt(br);
  
  mx = (int)((atan2((lx * d) - cx, (ly * d) - cy) + camera_rot) * (180 / PI)) % 360;

  lat = ((lz * d) - cz) / r;
  if(lat >= 1) lat =   0.99999;
  if(lat <= -1) lat = -0.99999;
  my = 180 - (int)(acos(lat) * (180 / PI));

  if(mx < 0)
    mx += 360;

  /*printf("my:%i\t-\t%f %f %f %f\n", my, acos(((lz * d) - cz) / r), ((lz * d) - cz), r, ((lz * d) - cz) / r);*/

  rt = (getpixel(world_map, mx * world_map->w / 360, my * world_map->h / 180) != 0x007F00) ? 1 : 0;

  return rt + 1;
}

/* ---------- END OF IMPORTANT PART ---------- */

SDL_Surface * load_image(char * filename)
{
  SDL_Surface * loadedImage = NULL;
  SDL_Surface * optimizedImage = NULL;
  loadedImage = IMG_Load(filename);
  if(loadedImage != NULL)
    {
      optimizedImage = SDL_DisplayFormat(loadedImage);
      SDL_FreeSurface(loadedImage);
    }
  return optimizedImage;
}

int init()
{
  if(SDL_Init(SDL_INIT_EVERYTHING) ==  -1)
    return 1;

  screen = SDL_SetVideoMode(screen_width, screen_height, screen_bpp, SDL_SWSURFACE);

  if(screen == NULL)
    return 1;

  text_width = screen_width / char_width;
  text_height = screen_height / char_height;

  return 0;
}

int main(int argc, char ** argv)
{
  Uint32 lastt, newt;
  int i;
  unsigned char * text = NULL;
  if(init())
    return 1;

  text = malloc(text_height * text_width);
  characters = load_image("characters.bmp");
  SDL_SetColorKey(characters, SDL_SRCCOLORKEY, 0xFF00FF);

  world_map = load_image("wmap2.png");

  for(i = 0; i < text_height * text_width; i++)
    text[i] = (i % (strlen("Hello, World!") + 1))["Hello, World!"];

  lastt = SDL_GetTicks();

  while(!quit)
    {
      Uint32 delta;
      Uint8 * keystate = NULL;
      if(SDL_PollEvent(&event))
	{
	  if(event.type == SDL_QUIT)
	    quit = 1;
	}

      newt = SDL_GetTicks();
      delta = newt - lastt;

      keystate = SDL_GetKeyState(NULL);

      if(keystate[SDLK_w])
	camera_x += 0.04 * delta;
      else if(keystate[SDLK_s])
	camera_x -= 0.04 * delta;
      if(keystate[SDLK_a])
	camera_y += 0.01 * delta;
      else if(keystate[SDLK_d])
	camera_y -= 0.01 * delta;

      if(keystate[SDLK_q])
	camera_rot += 0.001 * delta;
      else if(keystate[SDLK_e])
	camera_rot -= 0.001 * delta;
      
      SDL_FillRect(screen, NULL, 0);
      memset(text, 0, text_height * text_width);
      
      for(i = 0; i < text_height * text_width; i++)
	{
	  switch(raycast(i % text_width, i / text_height))
	    {
	    case 0:
	      text[i] = ' ';
	      break;

	    case 1:
	      text[i] = '#';
	      break;

	    case 2:
	      text[i] = (char)(247);
	      break;
	    }
	}

      draw_text(text);

      if(SDL_Flip(screen))
	return 1;

      lastt = newt;
    }

  return 0;
}