David Megginson wrote:
> Alex Perry writes:
> > Why can't we stick it into the scenery directories, but one directory
> > up from the tiles, so we have one file per 10degx10deg of planet.
> > That should ensure that FGFS doesn't need to load all that many files,
> > and just having the one file in the base package will allow initial use.
>
> It's not a bad idea, except that FlightGear needs to be able to search
> all the airports at once to find the one the user wants to jump to.
It seems to me like the airport database is only searched on two keys:
location and ID. Storing an "index" on location is trivial, as Alex
points out -- store it with the location-specific data structure that
is already indexed.
So all we need is an index on name. Not to be too glib, but the OS
already provides a rather nice index on named objects -- the
filesystem. So in Scenery/w130n30/airports.xml you will find a simple
list of airport ID's:
<airports>
<id>KSFO</id>
<id>KOAK</id>
...
</airports>
And look up the airport data itself under Airports/KSFO.xml:
<airport>
<id>KSFO</id>
<name>San Francisco Intl.</name>
<alt>...</alt>
<lat>...</lat>
<lon>...</lon>
<runway>
<name>11</name>
<lat>...</lat>
<lon>...</lon>
<direction>...</direction>
<length>...</length>
<width>...</width>
</runway>
<runway>
...
</runway>
</airport>
The astute will point out that not all filesystems actually store
indices on filenames (ext2 and FAT among them, sadly -- NTFS and
reiserfs do have indices). With only a few thousand files, this isn't
likely to be a real performance problem. Nonetheless, storing them
sorted into directories is possible. Use Airports/K/KSFO.xml, for
example, or even Airports/K/S/F/O.xml if you really want. :)
This strikes me as easy to implement and much easier to maintain than
the current metakit stuff.
Andy
--
Andrew J. Ross NextBus Information Systems
Senior Software Engineer Emeryville, CA
[EMAIL PROTECTED] http://www.nextbus.com
"Men go crazy in conflagrations. They only get better one by one."
- Sting (misquoted)
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