[Celestia-developers] Locations

[Chris L. <cl...@ww...>]

I checked in initial code for locations . . .  It's still in a primitive 
state, so don't expect too much.  Here are some samples:

Location "Seattle" "Sol/Earth"
{
    LongLat [ -122.5 47.5 0 ]
}

Location "Hamburg" "Sol/Earth"
{
    LongLat [ 9.93 53.6 0 ]
}

Location "Lyon" "Sol/Earth"
{
    LongLat [ 5.08 45.7 0 ]
}


(Didn't mean to leave you out Grant, but I don't know what your hometown 
is :) )

Locations are specified in .ssc files.  The only supported field right now 
is LongLat, but I will be adding more.

Work that remains:

- Define a feature class for locations--city, landing site, crater, 
chasma, valles, mons, etc.

- Make it possible to disable the display of locations either completely, 
or by feature type (e.g. show just craters)

- Add some sort of priority scheme so that some locations only appear when 
you've zoomed in far enough.  My sense is that this should be accomplished 
by assigning a size value to each location--when a sphere of the given 
size would occupy more than a pixel on screen, the location name is shown.  
Of course, this could be different than the actual size for small but 
significant features like landing sites and cities.

- Add fields to correct the surface coordinate systems of planets, as the 
IAU has been inconsistent in defining longitude and latitude within the 
solar system.  I thought that this would just be a matter of mirroring one 
or both of latitude and longitude, but perhaps something more 
sophisticated needs to me done?  I tried to add a location for Tycho on 
the Moon and could not properly place it.

--Chris