C++ Allegro Bitmapping Child Classes

Question

I have two child classes which are calling the same parent function.

One works fine, but the second call of it can't get past the al_convert_mask_to_alpha line.

I'm bamboozled once again.

Does anyone know why this may be happening?

The function below is what they both call. With the declarations of both above it.

Monster* the_monster = new Monster("chard", 10, 10, "assets/monstertrans.bmp");
Hero* the_hero = new Hero(1, "Player", 20, 20, "assets/hero.bmp");

the_monster->Display();
the_hero->Display();


void Creature::Display(void)
{
    //creating the bitmap
    al_init_image_addon(); //allegro image addon

    //FORGETTING THIS LINE WAS A SILLY IDEA!!!!
    creature_bit = al_load_bitmap(m_filename.c_str()); 

    al_convert_mask_to_alpha(creature_bit, al_map_rgb(255,0,255));

    al_draw_bitmap(creature_bit, m_xpos, m_ypos, 0);

    if (!creature_bit)
    {
        cout << "creature creation failed!" << endl;
        cout << "Any key to exit" << endl;
        _getch();
    }
}

`if (!creature_bit)` --- don't you think it's a bit late to check the bitmap after you have converted and drawn it? — n. m. could be an AI, Nov 11 '13 at 16:04

score 0 · Answer 1 · answered Nov 11 '13 at 19:10

Your code is not organized very well.

Initializing the add on should only happen one time at program start
Loading the bitmap should happen as part of the object's constructor (or immediately after, one time only)
Drawing the bitmap should happen once per frame (separate from the logic of updating the creature's x/y data)

Those all belong in separate methods.

If creature_bit is null, then you should read this article as it contains everything you need to know about how to load a bitmap properly.

C++ Allegro Bitmapping Child Classes

1 Answers1