upgrading tank war codebase to allegro 5

upgrading tank war codebase to allegro 5

DarkSlayer

Member #16,585

October 2016

Hi
I'm upgrading tank war to allegro 5 and See this code from old thread on the forum. I use the book, allegro wiki site and 2D Game Development Course site and forum to make it work.I am stuck on error: use of undeclared identifier 'screen' in line 31 and 26.I searched the forum and book and the old source code and I could not find the variable. can someone help me to upgrade it?

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   2void drawtank(int num)/*{{{*/
   3{
  int x = tanks[num].x;
  int y = tanks[num].y;
  int dir = tanks[num].dir;
   7
  //draw tank body and turret 
  al_draw_filled_rectangle(x-11, y-11, x+11, y+11, tanks[num].color);
  al_draw_filled_rectangle(x-6, y-6, x+6, y+6, GREY);
  11
  //draw the treads based on orientation 
  if (dir == 0 || dir == 2)
  {
      al_draw_filled_rectangle(x-16, y-16, x-11, y+16, DARK_GREY);
      al_draw_filled_rectangle(x+11, y-16, x+16, y+16, DARK_GREY);
  }
  else
  if (dir == 1 || dir == 3)
  {
      al_draw_filled_rectangle(x-16, y-16, x+16, y-11, DARK_GREY);
      al_draw_filled_rectangle(x-16, y+16, x+16, y+11, DARK_GREY);
  }
  24
  //draw the turret based on direction 
  switch (dir)
  {
      case 0:
          al_draw_filled_rectangle(x-1, y, x+1, y-16, DARK_GREY);
          break;
      case 1:
          al_draw_filled_rectangle(x, y-1, x+16, y+1, DARK_GREY);
          break;
      case 2:
          al_draw_filled_rectangle(x-1, y, x+1, y+16, DARK_GREY);
          break;
      case 3:
          al_draw_filled_rectangle(x, y-1, x-16, y+1, DARK_GREY);
          break;
  }
  al_flip_display();
  42}/*}}}*/
  43
  44
  45void erasetank(int num)/*{{{*/
  46{
  //calculate box to encompass the tank 
  int left = tanks[num].x - 17;
  int top = tanks[num].y - 17;
  int right = tanks[num].x + 17;
  int bottom = tanks[num].y + 17;
  52
  //erase the tank 
  al_draw_filled_rectangle(left, top, right, bottom, BLACK);
  al_flip_display();
  56}/*}}}*/
  57
  58
  59void movetank(int num)/*{{{*/
  60{
  int dir = tanks[num].dir;
  int speed = tanks[num].speed;
  63
  //update tank position based on direction 
  switch(dir)
  {
      case 0:
          tanks[num].y -= speed;
          break;
      case 1:
          tanks[num].x += speed;
          break;
      case 2:
          tanks[num].y += speed;
          break;
      case 3:
          tanks[num].x -= speed;
  }
  79
  //keep tank inside the screen 
  if (tanks[num].x > WIDTH-22)
  {
      tanks[num].x = WIDTH-22;
      tanks[num].speed = 0;
  }
  if (tanks[num].x < 22)
  {
      tanks[num].x = 22;
      tanks[num].speed = 0;
  }
  if (tanks[num].y > HEIGHT-22)
  {
      tanks[num].y = HEIGHT-22;
      tanks[num].speed = 0;
  }
  if (tanks[num].y < 22)
  {
      tanks[num].y = 22;
      tanks[num].speed = 0;
  }
 101}/*}}}*/
 102
 103
 104void explode(int num, int x, int y)/*{{{*/
 105{
 106
  int n;
 108
  //retrieve location of enemy tank 
  int tx = tanks[!num].x;
  int ty = tanks[!num].y;
 112
  //is bullet inside the boundary of the enemy tank? 
  if (x > tx-16 && x < tx+16 && y > ty-16 && y < ty+16)
      score(num);
 116
  //draw some random circles for the "explosion" 
  for (n = 0; n < 10; n++)
  {
      al_draw_filled_rectangle(x-16, y-16, x+16, y+16, RANDOM_COLOUR);
      /* rest(1); */
  }
 123
  //clear the area of debris 
  al_draw_filled_rectangle(x-16, y-16, x+16, y+16, BLACK);
  al_flip_display();
 127}/*}}}*/
 128
 129int cmp_colour(int x, int y, char r, char g, char b) {/*{{{*/
  unsigned char pixelr, pixelg, pixelb;
 131
  al_unmap_rgb(al_get_pixel(screen, x, y), &pixelr, &pixelg, &pixelb);
  if (r == pixelr && g == pixelg && b == pixelb)
      return 1;
  return 0;
 136}/*}}}*/
 137
 138
 139void updatebullet(int num)/*{{{*/
 140{
  int x = bullets[num].x;
  int y = bullets[num].y;
 143
  if (bullets[num].alive)
  {
      //erase bullet 
      al_draw_rectangle(x-1, y-1, x+1, y+1, BLACK, 0);
 148
      //move bullet 
      bullets[num].x += bullets[num].xspd;
      bullets[num].y += bullets[num].yspd;
      x = bullets[num].x;
      y = bullets[num].y;
 154
      //stay within the screen 
      if (x < 5 || x > WIDTH-5 || y < 20 || y > HEIGHT-5)
      {
          bullets[num].alive = 0;
          return;
      }
 161
      //draw bullet 
      x = bullets[num].x;
      y = bullets[num].y;
      al_draw_rectangle(x-1, y-1, x+1, y+1, YELLOW, 0);
 166
      //look for a hit 
      if (cmp_colour(bullets[num].x, bullets[num].y, 0xff, 0xff, 0xff)) // black 
      {
          bullets[num].alive = 0;
          explode(num, x, y);
      }
 173
      //print the bullet's position 
      //al_draw_textf(font, al_map_rgb(255, 255, 255), WIDTH/2-50, 1, 2, "B1 %-3dx%-3d  B2 %-3dx%-3d", bullets[0].x, bullets[0].y, bullets[1].x, bullets[1].y);
  }
  al_flip_display();
 178}/*}}}*/
 179
 180
 181int checkpath(int x1,int y1,int x2,int y2,int x3,int y3)/*{{{*/
 182{
  if (cmp_colour(x1, y1, 0xff, 0xff, 0xff) ||
          cmp_colour(x2, y2, 0xff, 0xff, 0xff) ||
          cmp_colour(x3, y3, 0xff, 0xff, 0xff))
      return 1;
  else
      return 0;
 189}/*}}}*/

 191void clearpath(int num)/*{{{*/
 192{
  //shortcut vars 
  int dir = tanks[num].dir;
  int speed = tanks[num].speed;
  int x = tanks[num].x;
  int y = tanks[num].y;
 198
  switch(dir)
  {
      //check pixels north 
      case 0:
          if (speed > 0)
          {
              if (checkpath(x-16, y-20, x, y-20, x+16, y-20))
                  tanks[num].speed = 0;
          }
          else
              //if reverse dir, check south 
          if (checkpath(x-16, y+20, x, y+20, x+16, y+20))
              tanks[num].speed = 0;
          break;
 213
          //check pixels east
      case 1:
          if (speed > 0)
          {
              if (checkpath(x+20, y-16, x+20, y, x+20, y+16))
                  tanks[num].speed = 0;
          }
          else
              //if reverse dir, check west 
          if (checkpath(x-20, y-16, x-20, y, x-20, y+16))
              tanks[num].speed = 0;
          break;
 226
          //check pixels south
      case 2:
          if (speed > 0)
          {
              if (checkpath(x-16, y+20, x, y+20, x+16, y+20 ))
                  tanks[num].speed = 0;
          }
          else
              //if reverse dir, check north 
          if (checkpath(x-16, y-20, x, y-20, x+16, y-20))
              tanks[num].speed = 0;
          break;
 239
          //check pixels west
      case 3:
          if (speed > 0)
          {
              if (checkpath(x-20, y-16, x-20, y, x-20, y+16))
                  tanks[num].speed = 0;
          }
          else
              //if reverse dir, check east 
          if (checkpath(x+20, y-16, x+20, y, x+20, y+16))
              tanks[num].speed = 0;
          break;
  }
 253}/*}}}*/
 254
 255
 256void fireweapon(int num)/*{{{*/
 257{
  int x = tanks[num].x;
  int y = tanks[num].y;
 260
  //ready to fire again? 
  if (!bullets[num].alive)
  {
      bullets[num].alive = 1;
 265
      //fire bullet in direction tank is facing 
      switch (tanks[num].dir)
      {
          //north 
          case 0:
              bullets[num].x = x;
              bullets[num].y = y-22;
              bullets[num].xspd = 0;
              bullets[num].yspd = -BULLETSPEED;
              break;
              //east
          case 1:
              bullets[num].x = x+22;
              bullets[num].y = y;
              bullets[num].xspd = BULLETSPEED;
              bullets[num].yspd = 0;
              break;
              //south
          case 2:
              bullets[num].x = x;
              bullets[num].y = y+22;
              bullets[num].xspd = 0;
              bullets[num].yspd = BULLETSPEED;
              break;
              //west
          case 3:
              bullets[num].x = x-22;
              bullets[num].y = y;
              bullets[num].xspd = -BULLETSPEED;
              bullets[num].yspd = 0;
      }
  }
 298}
 299void forward(int num)/*{{{*/
 300{
  tanks[num].speed++;
  if (tanks[num].speed > MAXSPEED)
      tanks[num].speed = MAXSPEED;
 304}/*}}}*/
 305
 306
 307void backward(int num)/*{{{*/
 308{
  tanks[num].speed--;
  if (tanks[num].speed < -MAXSPEED)
      tanks[num].speed = -MAXSPEED;
 312}/*}}}*/
 313
 314
 315void turnleft(int num)/*{{{*/
 316{
  tanks[num].dir--;
  if (tanks[num].dir < 0)
      tanks[num].dir = 3;
 320}
 321
 322void turnright(int num)/*{{{*/
 323{
  tanks[num].dir++;
  if (tanks[num].dir > 3)
      tanks[num].dir = 0;
 327}
 328void getinput()/*{{{*/
 329{
  ALLEGRO_EVENT ev;
  al_wait_for_event(event_queue, &ev);
  if (ev.type != ALLEGRO_EVENT_KEY_DOWN)
      ;
  else if (ev.keyboard.keycode == ALLEGRO_KEY_ESCAPE)
      gameOver = 1;
  else if (ev.keyboard.keycode == ALLEGRO_KEY_UP)
      forward(1);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_DOWN)
      backward(1);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_RIGHT)
      turnright(1);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_LEFT)
      turnleft(1);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_ENTER)
      fireweapon(1);
 346
  else if (ev.keyboard.keycode == ALLEGRO_KEY_W)
      forward(0);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_D)
      turnright(0);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_A)
      turnleft(0);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_S)
      backward(0);
  else if (ev.keyboard.keycode == ALLEGRO_KEY_SPACE)
      fireweapon(0);
 357
  //short delay after keypress         
  /* rest(10); */
 360}
 361void score(int player)/*{{{*/
 362{
  //update score 
  int points = ++tanks[player].score;
 365
  //display score 
  //al_draw_textf(font, BURST, WIDTH-70*(player+1), 1, 0, "P%d: %d", player+1, points);
  al_flip_display();
 369}
 370
 371void setuptanks()/*{{{*/
 372{
  //player 1 
  tanks[0].x = 30;
  tanks[0].y = 40;
  tanks[0].dir = 1;
  tanks[0].speed = 0;
  tanks[0].color = BLUE;
  tanks[0].score = 0;
 380
  //player 2 
  tanks[1].x = WIDTH-30;
  tanks[1].y = HEIGHT-30;
  tanks[1].dir = 3;
  tanks[1].speed = 0;
  tanks[1].color = RED;
  tanks[1].score = 0;
 388}/*}}}*/
 389
 390
 391void setupdebris()/*{{{*/
 392{
  int n,x,y,size,color;
 394
  //fill the battlefield with random debris 
  for (n = 0; n < BLOCKS; n++)
  {
      x = BLOCKSIZE + rand() % (WIDTH-BLOCKSIZE*2);
      y = BLOCKSIZE + rand() % (HEIGHT-BLOCKSIZE*2);
      size = (10 + rand() % BLOCKSIZE)/2;
      al_draw_filled_rectangle(x-size, y-size, x+size, y+size, RANDOM_COLOUR);
  }
  al_flip_display();
 404
 405}/*}}}*/
 406
 407
 408void setupscreen()/*{{{*/
 409{
 410#if 0
  //set video mode     
  int ret = set_gfx_mode(MODE, WIDTH, HEIGHT, 0, 0); 
  if (ret != 0) { 
      allegro_message(allegro_error); 
      return; 
  }
 417#endif
 418
  al_set_target_bitmap(screen);
  //print title 
  //al_draw_textf(font, BURST, 1, 1, 0, "Tank War - %dx%d", WIDTH, HEIGHT);
 422
  //draw screen border         
  al_draw_rectangle(0, 12, WIDTH-1, HEIGHT-1, TAN, 0);
  al_draw_rectangle(1, 13, WIDTH-2, HEIGHT-2, TAN, 0);
  al_flip_display();
 427}/*}}}*/
 428
 429
 430int main(int argc, char **argv)/*{{{*/
 431{
 432
  bool done = false;
  bool render = false;
 435
  float gameTime = 0;
  int frames = 0;
  int gameFPS = 0;
 439
 440
  ALLEGRO_DISPLAY *display = NULL;
  ALLEGRO_EVENT_QUEUE *event_queue = NULL;
  ALLEGRO_TIMER *timer;
  ALLEGRO_FONT *font;
 445
 446
  al_install_keyboard();
  al_init_image_addon();
  al_init_font_addon();
  al_init_ttf_addon();
  al_init_primitives_addon();
 452
 453
 454
  font = al_load_font("arial.ttf", 18, 0);
 456
 457
  event_queue = al_create_event_queue();
  timer = al_create_timer(1.0 / 60);
 460
  al_register_event_source(event_queue, al_get_timer_event_source(timer));
  al_register_event_source(event_queue, al_get_keyboard_event_source());
 463
  al_start_timer(timer);
  gameTime = al_current_time();
 466
  //initialize everything 
 468
  if (!al_init()) {
      printf("Failed to initialize Allegro library.\n");
      return 1;
  }
 473
  if (!al_install_keyboard()) {
      printf("Failed to install keyboard.\n");
      return 1;
  }
 478
  /* install_timer(); */
  srand(time(NULL));
  al_init_font_addon();
  if (!(display = al_create_display(640, 480))) {
      printf("Failed to create display.\n");
      return 1;
  }
 486
  ALLEGRO_PATH *path = al_get_standard_path(ALLEGRO_RESOURCES_PATH);
  al_append_path_component(path, "resources");
  al_change_directory(al_path_cstr(path, '/'));  // change the working directory 
  printf("Should be in %s\n", al_path_cstr(path, '/'));
  font = al_load_ttf_font("Airacobra Alt.ttf", 72, 0);
  if (!font) {
      printf("Error loading Airacobra Alt.ttf.\n");
      return 1;
  }
  al_destroy_path(path);
 497
  setupscreen();
  setupdebris();
  setuptanks();
 501
  //game loop 
  while(!gameOver)
  {
 505#if 0
      //erase the tanks 
      erasetank(0); 
      erasetank(1); 
       
      //check for collisions 
      clearpath(0); 
      clearpath(1); 
       
      //move the tanks 
      movetank(0); 
      movetank(1);
 517#endif
 518
      //draw the tanks 
      drawtank(0);
      drawtank(1);
 522
 523#if 0
      //update the bullets 
      updatebullet(0); 
      updatebullet(1);
 527#endif
 528
      //check for keypresses 
      ALLEGRO_EVENT ev;
      al_wait_for_event(event_queue, &ev);
      if (ev.type == ALLEGRO_EVENT_KEY_DOWN)
          getinput();
 534
      //slow the game down (adjust as necessary) 
      al_rest(30);
  }
 538
  //end program 
  return 0;
 541}/*}}}*/

Edgar Reynaldo

Major Reynaldo

May 2007

In Allegro 4, references to screen are used to draw directly to the screen. In Allegro 5, when you want to draw to the screen, you need to set the target bitmap to the back buffer of the display you are using.

/// OLD Allegro 4 code
blit(bmp , screen , 0 , 0 , 0 , 0 , bmp->w , bmp->h);

/// Equivalent Allegro 5 Code
al_set_target_bitmap(al_get_backbuffer(display));
al_draw_bitmap(bmp , 0 , 0 , 0);

Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide
King Piccolo will make it so Then I could just flip it with some sweet, sweet matrix math. In either case, I’ll ride this wagon until the wheels fall off. Thanks to those that keep it running