On 14 Sep 2011, at 14:34, Scott wrote:

> I'm playing around with extending the NasalSys.cxx navinfo() function that 
> torsten wrote.
> >From what I can tell it calls navlist.cxx findByIdentAndFreq(position, 
> >ident, freq, type)
> which then calls findByIdentAndFreq(ident, freq, type) and does a distance 
> filter on the result.
> 
> The problem is the findByIdentAndFreq() methods require a partial Id, and 
> this isn't always the case.
> I'd like to be able to call navinfo() with a position and radius distance, 
> and to get back a list of all navaids within the radius range.
> 
> Is there another method that I haven't seen that would return the nearest 
> navaids items from the database?

There is, one of the FGPositioned spatial queries, which could be exposed via 
Nasal. However, I already exposed these via an alternate method - I didn't want 
to add lots of Nasal proxies for each item we have. You can issue a search via 
a regular flightgear command, and the resulting navaid(s) can be stored into an 
arbitrary property tree location.

The command is called 'find-nearest', it takes a maximum search radius in NM, a 
search position, and list of types to search on (NDB, ILS, VOR, or anything 
else in the positioned DB). 

Eg, from Nasal:

        fgcommand("find-nearest", props.Node.new({type: "vor", max-results:10, 
results:"/some/node/path"}));

Will load the ten closest VORs to the current aircraft lat/lon below 
/some/node/path

(or as many as possible within the default search radius, 400 nm)

James

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