.altx file format

[19 cm]

I peeked into Altitude's map files out of curiosity and found it's a very straightforward and efficient format, so I'll describe it here in case anyone's interested.

The entire file is a compressed LZMA stream (that's what the 7z archiver uses). So for instance if you have 1bd_core.altx, you can do

7z x 1bd_core.altx

and you'll get a file named 1bd_core with the following structure:

int32   number of files (let's call it N)
-----------------------------
N filename records, tightly packed: no word alignment.
{
  int16   length
  byte[]  filename, no trailing zero
}
-----------------------------
array of N file lengths (int32).  no alignment.
-----------------------------
data for file 1
-----------------------------
...
-----------------------------
data for file N

Filenames can (and do) include path, e.g. _config/image-descriptors.txt

The directory structure corresponds to what you can see in Altitude/editor/maps/_imported_map. At a minimum it will be:

1de_imported_map.alte
_derived/dist/.image/pck.txt
_derived/dist/.sound/convert.txt
_derived/dist/.sound/precache.txt
_config/image-descriptors.txt

The name of the .alte file doesn't seem to matter; most .altx files contain a corresponding .alte as first entry, but some have "1de_imported_map.alte", and 1de_lazer.altx contains obj_lazer.alte

The contents of most files is XML encoded, but interestingly _derived/dist/.image/pck.txt appears to consist of random-looking binary data.