If on bitmaps

If on bitmaps

paparam

Member #16,847

April 2018

Hello.
Im trying to make if on bitmap.
I have randomly loaded bitmap in loop and i want to do so if it rolls a certain one, lets call it xxx.bmp i want to make something different than others but i can't quite find out how to make a instruction.

If i do like this

if(something=="xxx.bmp"){
(...do something)
}else
(...do something)

it doesnt work so i guess im doing it the wrong way.
What's the proprer way to do thing like this?

Edgar Reynaldo

Major Reynaldo

May 2007

#SelectExpand
  1ALLEGRO_BITMAP* bmp1 = al_load_bitmap("xxx.bmp");
  2ALLEGRO_BITMAP* bmp2 = al_load_bitmap("xxy.bmp");
  3ALLEGRO_BITMAP* bmp = bmp1;
  4
  5bool quit = false;
  6
  7while (!quit) {
 al_set_target_backbuffer(display);
 al_clear_to_color(al_map_rgb(0,0,0));
 if (bmp) {
    al_draw_bitmap(bmp , 0 , 0 , 0);
 }
 al_flip_display();

 do {
    ALLEGRO_EVENT ev;
    al_wait_for_event(queue , &ev);
    if (ev.type == ALLEGRO_EVENT_KEY_DOWN && ev.keyboard.keycode == ALLEGRO_KEY_Y) {
       bmp = bmp2;
    }
    if (ev.type == ALLEGRO_EVENT_KEY_DOWN && ev.keyboard.keycode == ALLEGRO_KEY_X) {
       bmp = bmp1;
    }
    if (ev.type == ALLEGRO_EVENT_KEY_DOWN && ev.keyboard.keycode == ALLEGRO_KEY_SPACE) {
       bmp = 0;
    }
    if (ev.type == ALLEGRO_EVENT_KEY_DOWN && ev.keyboard.keycode == ALLEGRO_KEY_ESCAPE) {
       quit = true;
    }
 } while (!al_is_event_queue_empty(queue));
 31}

EDIT
Perhaps I misunderstood. Maybe you meant how do I choose a certain bitmap?

Have you ever heard of enums or arrays? switch statements? those would be useful here. you can also use string comparisons, for example in a std::map.

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Audric

Member #907

January 2001

From looking at your other post, I think you're making the mistake of mixing the loading of resources with the identification of things (what the user is clicking, what he clicked last)
You should really separate :

#SelectExpand
  1// The storage of graphic resources. If you have many, you may prefer an array.
  2BITMAP* sprite_king;
  3BITMAP* sprite_knight;
  4
  5// The current state of what the player has selected
  6int selected_piece=0; // 0= none, 1=king, 2=knight
  7BITMAP * current_image=NULL; // image relevant to the selected piece 
  8
  9// The loading of resources, should run only once, when program starts (but after allegro init)
 10load_graphics()
 11{
 12  sprite_king = load_bitmap("king.bmp");
 13  sprite_knight = load_bitmap("knight.bmp");
 14}
 15
 16// Collision detection : when you detect the player points at something
 17if(mouse_x>45&&mouse_x<370&&mouse_y>132&&mouse_y<190)
 18  if(mouse_b==1){ // king
 19    selected_piece=1;
 20    current_image = sprite_king;
 21  }
 22}
 23if(/*other coordinates*/)
 24  if(mouse_b==1){ // knight
 25    selected_piece=2;
 26    current_image = sprite_knight;
 27  }
 28}
 29
 30// Checking this information, for gameplay purpose
 31if (selected_piece == 1) // when the king is selected
 32{
 33  ....
 34}
 35
 36// drawing whatever piece is currently selected
 37if (current_image)
 38{
 39   draw_sprite(screen, current_image , x, y);
 40}