Just as a little learning project, I want to make an allegro program that just has a sprite on the display, and it walks left when press left, right when I press right etc. Basically all I have done so far is make a pong game which just used primitive bitmaps, rather than loading an image. So basically I just need to know how sprites work.

I need to know where does the sprite come from? Do I take a sprite sheet from google and load a section of that image file into the program?

When the sprite moves, how exactly do I put in the animation? Do I time it so that while a keyboard event is occurring, the program cycles through a few different images on a sprite sheet?

And if there is anything else I should know then I would appreciate any advice you all could give me

oh nice! Good thing my class just covered how to do OOP!

But on a simpler scale. I don't even know how to draw a sprite to the display. I've looked through the allegro manual and I can't find any functions that take in an image file or anything to draw to the display. All I can think of is creating a bitmap, and filling it with a colour

Are you using Allegro 4 or Allegro 5?

Allegro 4 :
load_bitmap
draw_sprite

Allegro 5 :
al_load_bitmap
al_convert_mask_to_alpha
al_draw_bitmap

Yes.

I think I need to add a second example to that bitmap tutorial that uses the image addon.

I guess you've figured out from the posts above that there really isn't any such thing as a sprite. In the olden days, the Commodore 64 had sprites. A sprite is just a bitmap that appears to animate simply because you are replacing it with another bitmap, i.e. a sprite is a class you create to manage, control and show the graphics in order

Forget about palettes. They are only used in 8 bit graphics and A5 doesn't support them.

Regarding al_convert_mask_to_alpha(): A5 uses the alpha channel to support transparency. A4 didn't and instead usually relied on 'magic pink', i.e. 255,0,255 magenta. So, al_convert_mask_to_alpha will look at your bitmap and any magenta pixel will be converted to transparency.

I've never used al_draw_bitmap_region(), but that looks a little off. because your changing units from pixels to pictures with this line:

animationWidth = al_get_bitmap_width(bmp)/32;
...

To get just the top left image with al_create_sub_bitmap(). you'd do this:

bmp = al_load_bitmap("player.png")
ALLEGRO_BITMAP* top_left_image = al_create_sub_bitmap(bmp, 0, 0, 32, 32);

and draw with al_draw_bitmap(top_left_image, x, y, 0)

It just makes more practical sense to create an entire array at once though. so if you have a 4x4 sheet and 32x32 tiles...

bmp = al_load_bitmap("player.png")
ALLEGRO_BITMAP* bmp_array[4][4];

for (int x = 0; x < 4; x++)
{
  for (int y = 0; y < 4; y++)
  {
    bmp_array[x][y] = al_create_sub_bitmap(bmp, 32*x, 32*y, 32, 32);
  }
}

sprite.bmp = bmp_array[0][0];

Also instead of creating the variables sprite_x, and sprite_y, you should just make them private members of your player class, and write public functions to modify the values. Same goes for the bitmap so you can switch which element in the bitmap array is getting drawn.

Ok I did it! I now have a program that draws a piece of the sprite sheet to the display! Now for animation, which is going to be quite the mountain for me to conquer

@Edgar
I've been looking at the code you posted in the first reply. It all looks good an makes sense to me now, I just don't quite know how to keep track of time in a program. (whether in an allegro program or in a regular C++ program). The only thing I can think of is using my FPS constant with the allegro timer, making the animation state change every 15 frames or so. Would that be how you would go about tackling that problem?

Also that map<string , Animation*> in the animationState class, what is that?

Thanks for all the help so far btw everyone, this is awesome!

Just to clarify, this isn't for a class, allegro programming is something I'm just learning on my own time. The course I mentioned earlier is just a regular computer science course.

On the other hand though, that is useful. I'll have to play around with events some more

Ok I'm trying to use the code you put in the first response with the animation, stateAnimation and character classes. I'm still trying to wrap my head around the map thing, but I'm wondering if I can get away without using it. I worked on it a bit today but this is about as far as I got

sprite.h:

sprite.cc:

I changes some stuff from the original post, and I haven't filled in the player or the animation state class yet. I haven't figured out what exactly the setFrameTime and advanceFrameTime functions should do. One second I'm thinking that setFrameTime will set the duration, but then I think why wouldn't you just do that in the constructor... Maybe it's just because I need to step away from this for a second..