sizeof is a compile time thing, so there's no way it could return anything except the size of the pointer.

Also, what you are doing is not guaranteed to work. You need to load the data into a memfile and then use al_load_bitmap_f. Or if you are using 5.1, you can use al_fopen_slice.

Sorry if the memfile docs aren't entirely clear.

You pass in a block of memory, it returns an ALLEGRO_FILE which you can then use the allegro file/fshook api on as if it were a real file. So things like al_load_bitmap work on chunks of memory.

A void pointer is just a way of specifying its just a pointer with no specific type associated.

Nope. Allegro does not load anything into memory when you al_fopen a file. You have to manually load the data with one or more of the al_fread* functions.

Some image loaders like to seek around and not set the file position to 1 byte past the end of the last byte of the individual image. So when you try to load the next image, it starts at the wrong place. If you read each image into a chunk of memory and use the al_load_bitmap_f function to load from the memfile, there won't be any problems.

Ah, I think I understand now. I'll give it a shot. Thanks a lot both of you

I'm using 5.3, which means no al_fopen_slice. Why does 5.3 not have an equivalent function? It seems pretty useful.

Do you think it would be worth switching to the development version?

also, I'm fairly certain I still don't have the syntax for al_open_memfile right.

datfile = al_fopen("test.dat", "rb");
membuffer = al_open_memfile(membuffer,al_fsize(datfile),"rwb");
al_fread(datfile, membuffer,al_fsize(datfile));

sprite = al_load_bitmap_f(membuffer,".png");

I'm still unsure what I should pass as the void *mem parameter.

now I'm 100% lost

The image data that I want to use is contained in an external file, and I'm having trouble creating 2 bitmaps from it using al_load_bitmap; how does it help me to create a memfile from the single bitmap?

this code compiles and the application doesn't crash, but al_draw_bitmap(sprite) does nothing.

EDIT
So al_fread returns 0 meaning, I assume, it didn't copy anything into the membuffer, which means its empty? or does it contain the bitmap data from when I loaded sprite using al_load_bitmap_f the first time.

Okay, I thought I needed to use some memory allocation, but my C++ professor is an old IBM project bum, and he's far more concerned with teaching UML than practical C++.

I'll take a shot at it and let you know how badly I screw up

Thank you for being so patient btw.

EDIT: the only usage I know of new is when I'm instantiating an existing construct.

al_fread says to give it the pointer that refers to a buffer, but I wouldn't literally type bitmapBuffer = new buffer would I?

I've read PhysicsFS on the API, but I didn't know how difficult it would be to include it in my project, so I didn't really consider it.

I'll do some more looking.

Do you know off-hand if the compression-decompression has any performance overhead?

EDIT:
It appears that only the source files are available, and I don't have the slightest hint of how to create the windows binaries I think i would need

I think most of your problems stem from not quite knowing the language well enough. You might want to do some more studying.

When you want to create a buffer of bytes with new, you do something like:

char *buffer = new char[buffer_length];

It may be now, but it wasn't in 5.0.2 at least.

Oh wow, I just spent half an hour building physfs with cmake and visual studio and now I realize that the binaries are included with the allegro 5.0.3 distribution

DERRRRRRRP

I can initialize physfs and it can open files just fine, but when I call
al_set_physfs_file_interface(); it grayscreens and the program goes unresponsive

EDIT: Nevermind, the problem occurs after I set the file interface. I'll find it and fix it.

EDIT: So it wasn't working because it was actually working correctly, odd as it seems.

I assumed that the compile directory stayed on the filesystem but you have to explicitly add it to the search path with PHYSFS_mount(). So everything works fine and dandy now, I can read files from a virtual filesystem handled by PhysicsFS that is created from a .zip of my resources.

Everything is so complicated. >___________< it all works, but it feels like if I sneeze on the damn thing everything will explode and I'll have to spend an hour trying to tape it back together again. thank you all for you help, though I warn you this is probably not the last time I'll need it.
If anyone needs some 2D graphics, I'd be glad to give something back instead of just being an information leech.