[Xastir] New code testing

[Curt Mills, WE7U]

On Wed, 23 Jul 2003, Bryce Wolfson wrote:

> Keep a running average count of how long it takes to draw the map (perhaps
> 5-10 draws' worth), then at the beginning of a map draw take the GPS input
> course and speed to project your position out the duration of a map draw,
> and draw the map centered there. If course/speed change during the draw you
> won't be at the center of the map by the time it's done drawing, but then
> you apparently aren't at the center by the time it's done drawing using the
> last-position-before-draw technique, either.
>
> Regarding the map interrupt handling showing nothing vs. copying each map to
> the display individually -- just copy the current aggregate image to the
> display when an interrupt is received, only if the regular flush (on map
> drawing completion) hasn't already occurred, _then_ abort and start the next
> draw. This way you don't see the compositing happening, but if you run out
> of time the flush should be a very quick operation by comparison to all the
> drawing.
>
> Both techniques get a lot of use in the real-time graphics world; the latter
> can be used alone to improve things, but it works particularly well if you
> do both -- try to project the correct position, then if the target goes off
> the map before you're done drawing it (significant course and speed change,
> or significant error in position projection) invoke the second technique of
> bailing with a flush and reset.

Sweet!  I really like both of these techniques.  Neither one would
be difficult to implement.  The second one is particularly easy.  I
think I'll add that one in right away.  The running average
targeting technique will probably have to wait for another day, but
I want that in there.

What's the SAR mean in your address?  Another SAR guy?  If so, where
at?  Civilian or Military SAR?

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