Allegro DrawSprite() wont function correctly C++

Question

Simple x's and O's game. If 1-9 keys are pressed, draw an X or an O at the right place on the board:

7|8|9

4|5|6

1|2|3

The code is below, the changePlayer() function just changes the player (not included) and i use board[0] to hold which player it is.

When I run the program board is displayed correctly but X's and O's aren't drawn when i press a key.

I have tried to draw everything to the buffer then draw the buffer to the screen but wont work. If I dont use a buffer and just draw everything straight away to screen - it works perfectly!

I'm sure I'm missing something simple :S Here's the code:

int main()
{
int winner = 0;
BITMAP *xSprite;
BITMAP *oSprite;
BITMAP *newSprite;

int board[10];
int i = 0;

for(i=0; i<10; i++)
{
    board[i] = 0;
}

allegro_init();
install_keyboard();
set_color_depth(16);
set_gfx_mode( GFX_AUTODETECT, 1920, 1080, 0, 0);

xSprite = load_bitmap( "x.bmp", NULL);

oSprite = load_bitmap( "o.bmp", NULL);

BITMAP *buffer = create_bitmap(1920, 1080);

//draw black background
rectfill(buffer,0,0,1920,1080,makecol(0,0,0));
//draw white grid
line( buffer, 200, 0, 200, 480, makecol( 255, 255, 255));
line( buffer, 400, 0, 400, 480, makecol( 255, 255, 255));
line( buffer, 0, 150, 680, 150, makecol( 255, 255, 255));
line( buffer, 0, 300, 680, 300, makecol( 255, 255, 255));

acquire_screen();
blit(buffer, screen, 0, 0, 0, 0, 1920, 1080);
clear_bitmap(buffer);
release_screen();

while(!key[KEY_ESC])
{
  clear_keybuf();

  if (board[0] == 0)
    newSprite = xSprite;
  else
    newSprite = oSprite;

  acquire_screen();

  if(key[KEY_7] && board[7] == 0) {draw_sprite( screen, newSprite, 0, 0); board[7] = 1+board[0]; board[0] = changePlayer(board[0]);}
  if(key[KEY_8] && board[8] == 0) {draw_sprite( screen, newSprite, 200, 0); board[8] = 1+board[0]; board[0] = changePlayer(board[0]);}
  if(key[KEY_9] && board[9] == 0) {draw_sprite( screen, newSprite, 400, 0); board[9] = 1+board[0]; board[0] = changePlayer(board[0]);}

  if(key[KEY_4] && board[4] == 0) {draw_sprite( screen, newSprite, 0, 150); board[4] = 1+board[0]; board[0] = changePlayer(board[0]);}
  if(key[KEY_5] && board[5] == 0) {draw_sprite( screen, newSprite, 200, 150); board[5] = 1+board[0]; board[0] = changePlayer(board[0]);}
  if(key[KEY_6] && board[6] == 0) {draw_sprite( screen, newSprite, 400, 150); board[6] = 1+board[0]; board[0] = changePlayer(board[0]);}

  if(key[KEY_1] && board[1] == 0) {draw_sprite( screen, newSprite, 0, 300); board[1] = 1+board[0]; board[0] = changePlayer(board[0]);}
  if(key[KEY_2] && board[2] == 0) {draw_sprite( screen, newSprite, 200, 300); board[2] = 1+board[0]; board[0] = changePlayer(board[0]);}
  if(key[KEY_3] && board[3] == 0) {draw_sprite( screen, newSprite, 400, 300); board[3] = 1+board[0]; board[0] = changePlayer(board[0]);}

  release_screen();
}
return 0;

}   
END_OF_MAIN();

I would suggest a few things that probably will make it a little easier to understand your code: ** Use functions to do "almost the same thing several times". ** Do not write several statements on the same line unless they are REALLY simple. Are you sure any if your `if(key[...] && board [...] == 0)` is ever true? — Mats Petersson, Dec 22 '12 at 14:47
Yeah sorry, was just battering this code out quickly to get to grips with allegro, then it started not working and I was like o.O but yeah all board[0-9] is initialised to zero. Unless key[KEY_.] is always returning false is should work. Very weirdly, while the program loads up if i quickly press numbers - it draws the X's and O's. It just stops doing anything after the grid is visible on the screen :S — JamesB123, Dec 22 '12 at 14:59

score 2 · Accepted Answer · answered Dec 23 '12 at 05:42

Some general pointers given that Allegro 4 is really old and doesn't always work well on modern OS's:

If you're just starting, use Allegro 5
Always use set_color_depth(desktop_color_depth()) for maximum compatibility.
Use GFX_GDI for maximum compatibility. (Obviously not the fastest driver, but for simple games, it doesn't matter.)
Don't use acquire_screen() and release_screen()

For your particular problem, there's nothing much to say because the code you posted apparently works for you. If you are using a buffer, of course you need to be sure to blit it to the screen on every frame.

Thanks, it was the aquire screen and release screen that was causing it — JamesB123, Jan 09 '13 at 22:57

Allegro DrawSprite() wont function correctly C++

7|8|9

4|5|6

1|2|3

1 Answers1