[Xastir-Dev] dead-reckoning, revisited

[Curt Mills, WE7U]

On Fri, 8 Nov 2002, J. Lance Cotton wrote:

> we now have wind barbs as well as a function for drawing a
> circle around a station (for tracking). It seems to me that
> this could be combined *very* easily to enable dead-reckoning.
>
> For every update of the pixmap, draw a circle around the
> station representing the area that the station *could* be
> in, if it kept the same speed. Also, draw a "calm"
> wind barb
> in the direction of travel of the station, so that you can
> also see (where the wind barb and circle intersect) where
> the station would be if it maintained both its current speed
> and its current heading.
>
>  From that point, perhaps a clone/modification could be made
> of the circle-drawing function so that it fills in the
> circle with an increasingly transparent fill.
>
> Seems to me from looking at the code that most of the guts
> of this exists. I tried playing around with it, but I need
> to study the code more to understand xastir-coordinates and
> some of the X drawing routines.

Olivier is currently tasked with Dead-Reckoning.  He's pretty busy
at the moment, but he was interested in it and wanted to tackle it.
The drawing stuff is not difficult.  A good representation on the
screen is what we're after, and Olivier has ideas on how he wants to
handle it.

We'll need to tie into main.c:UpdateTime() with a routine that gets
run regularly, and probably need to add another item to the DataRow
struct in db.h to hold the Dead-Reckoned position of a station.
This is all easy stuff, it just requires some time.

If you want to work on this, please coordinate with Olivier so that
there's no duplication of efforts and to make sure the final product
is something we'll be happy with in the long run.  This is one where
it's better to do a bunch of thinking/testing up-front to make sure
it's done right the first time.

-- 
Curt Mills, WE7U                    hacker_NO_SPAM_ at tc.fluke.com
Senior Methods Engineer/SysAdmin
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