[Xastir] Line of sight

[Curt, WE7U]

On Tue, 17 May 2005, Rob Campbell wrote:

> Well, what I would be using it for would be stations that don't move.
> It would make more sense generally for it to be all positions it heard
> directly.

Yep.


> So when I add the stations/objects I would want to start with it at the
> base station and move it away to it's final position?  That way Xastir
> handles the lines as just normal tracks?

Create an object at the base station.  Move it out to the remove
object and then back.  Move it out to the next one and back.  Repeat
as necessary.  Use a tiny object like a red dot perhaps so that it
doesn't obscure the base station when you're all done.  When the
base station transmits it should obscure the dot.


> How hard would it be for Xastir to draw the relationship lines itself?
> I have some programming experience, but I haven't really looked at the
> Xastir code.

Like I said, it could be done.  Xastir is generic C-code.  Trickiest
part would probably be adding the widget controls for the user
interface.  If you would like to do the back-end code for this
function, making sure to generalize it so that one could find out
which stations were heard by any particular station, I'd volunteer
to make the user interface tie-in for it.

First problem I can think of is that I'd like to see all positions
that a digipeater could see directly, and Xastir doesn't keep the
path information for previous positions.  For your application of
non-moving stations it's not a big issue.  For moving stations it
is.

Look at src/database.h.  In there are the structure definitions for
the info kept for each station.  We keep the data in a
multiply-linked-list structure, where we can get to it by time
(either order) or by alpha-sorted-order, and we have an additional
hash that lets us shortcut the linked list too.  Just figure out the
data struct itself, navigating through all the stations is easy.

--
Curt, WE7U.   APRS Client Comparisons: http://www.eskimo.com/~archer
"Lotto:    A tax on people who are bad at math." -- unknown
"Windows:  Microsoft's tax on computer illiterates." -- WE7U
"The world DOES revolve around me:  I picked the coordinate system!"