Thread: A small problem with bitmaps and classes in Alllegro 5

Hello. I'm programming a 2D game in Allegro, and I'm stuck in the very beggining. I have a main program and a class for the player. In that class, I have a function who draws a circle:

Code:

void PlayerBen::draw() {
         al_draw_filled_circle(x,y,30,al_map_rgb(0,0,0));
//x and y are two variables that belong to the class
     }

In my main program I have initialized some allegro stuff, and I have a circle who moves throught the screen. Everything works fine.
The problem starts when I want to create a bitmap variable to change the primitive circle for something else. I created, inside of the class, a variable ALLEGRO_BITMAP *bitmap; and I changed the code in the function draw for that:

Code:

void PlayerBen::draw() {
         al_draw_bitmap(bitmap,x,y,0);
      }

Well, the problem could be the way I inicialize the *bitmap variable. This is the constructor of the class:

Code:

PlayerBen::PlayerBen(int Vidas, int Speed, int X, int Y,ALLEGRO_BITMAP *Bitmap) {
         vidas= Vidas;
         speed= Speed;
         x= X;
         y= Y;
         bitmap= Bitmap;
     }

The parameter *Bitmap is correctly inicialized in the main program. I also draw that bitmap in the main program with the same order that I use inside my class,just for testing, and it works. But when I call the function draw, the program crash. What's happening here?

I tried to be as specific as I could, to make things easier if anyone wants to help, or ask something. Thank you in advance for the help.

Yes, I create a pointer to an ALLEGRO_BITMAP, and that pointer is what I pass to my constructor. The code is here_

In the main program, I use that part of the code to create and initialize a bitmap variable:

Code:

ALLEGRO_BITMAP *bitmap_Ben;
al_init_image_addon();
bitmap_Ben=al_create_bitmap(BITMAP_BEN_WIDTH,BITMAP_BEN_HEIGHT);
bitmap_Ben=al_load_bitmap("GuyBen.png");

And then I use the constructor to create my player:

Code:

PlayerBen player(PLAYER_INIT_LIVES, PLAYER_INIT_SPEED, PLAYER_INIT_X_POS, PLAYER_INIT_Y_POS, bitmap_Ben);

Here is also the full header file of the PlayerBen class:

Code:

#ifndef PLAYER_BEN
#define PLAYER_BEN

#include <allegro5\allegro5.h>
#include <allegro5\allegro_primitives.h>
#include <allegro5\allegro_image.h>
#include <allegro5\allegro_native_dialog.h>

namespace myPlayerBen {
    class PlayerBen {
    public:
        PlayerBen();
        PlayerBen(int Vidas, int Speed, int X, int Y,ALLEGRO_BITMAP *Bitmap);

        void moveToLeft();
        void moveToRight();

        int getLives();
        void setLives(int lives);

        void draw(ALLEGRO_DISPLAY *Display);

    private:
        ALLEGRO_BITMAP *bitmap;
        int vidas;
        int speed;
        int x;
        int y;
    };
}
#endif

I can put the full main program and the PlayerBen.cpp file if you want it.

I checked it. In the main function it's ok, but in the class variable the bitmap is NULL. I don't get it...

Oh, I found the mistake....I'm so silly... I had the initialation code separated in a function called init(), and in the main function I was calling init() AFTER the class constructor... ¬¬ (Oh, C'mon, I'm better than this) Thank you, anyway. Now it works completely fine.