Ticket #533: waypoint.README

100103  17:25 this script used to feed navit a list of destinations, one at the time
and set the next waypoint as destination if you are near the current waypoint

This makes it possible to set a route from A to B via C,
by just puting the lat/lon pairs in a file:
51.1234;5.1234;Point A
52.1234;6.1234;Point C
53.1234;7.1234;Point B

And if A is your starting point, that can be ommitted altogether.

So instead of having the shortest route, or the fastest route, you can now plan a
route along a road with the maximum number of sharp bents in it.
(ideal for motorcycle lovers)
Or you can share a route you drove and enjoyed with others.
I think you can use itinerary files used by other navigation software too, if they have the fields in the same order.

How does this all work?
Well, the script is intended to be placed in the subdirectroy "scripts" in your home directory (mkdir ~/scripts)
and to be started by cron every minute. (* * * * * if test -x ~/scripts/waypoint.sh; then ~/scripts/waypoint.sh; fi)
It will then read nmea data from gpsd (needs to be running anyway)
and convert that data with gpsbabel.  (needs to be installed)
This wil give you the current lat/long.
If the current lat/lon is close enough to the current waypoint, the next waypoint is set as destination by a dbus call.
(libbinding_dbus.so" active="yes" needs to be set in navit.xml and dbus needs to be running, but it probably is)

How close is close?
Well, that is defined by the MAX_DELTA parameter in the script.
for example, with max_delta=10000 and the waypoint at lat=52.100 and long 5.100 then any location between 52.000,5.000 and 52.200,5.200
would be considered "close" (100 * 100 = 10000)

                                              52.100,5.100 and 52.100,5.100 
with a max_delta of 1024 any location between 52.068,5.068 and 52.132,5.132 would be close ( 32 * 32 = 1024 ) -> aprox 10   Km radius at this latitude
with a max_delta of  100 any location between 52.090,5.090 and 52.110,5.110 would be close ( 10 * 10 =  100 ) -> aprox  2   Km radius at this latitude
with a max_delta of    9 any location between 52.097,5.097 and 52.103,5.103 would be close (  3 *  3 =    9 ) -> aprox  0.1 Km radius at this latitude
If this script is ran every minute and your max speed is 120 Km/h (=2 Km/min) you don't want to go below max_delta=100,
or you might overshoot your waypoint.

In case you can not reach your next waypoint because there is a roadblock or you changed your mind, do the following:
edit the ~/itinerary.csv file and remove the problematic waypoints.
Then remove the destination.set file (rm /dev/shm/destination.set).
The next time the script is run by cron the new waypoint is set as destination.

It is easiest to keep a source file and copy that to the ~/itinerary.csv file,
the ~/itinerary.csv is removed and recreated every time you are near a waypoint.

This script is free software, feel free to use and/or modify it in anyway you like, for example add fields to have a per waypoint max_delta.
Please don't operate a laptop/pda while driving, let someone else drive while you use this script.

Have fun, adn drive safely!

Kind regards,
Ed