[android-developers] Re: How to find alternate routes for navigation and how to tell when user goes off path

well....

2. is just geometry and math. Assuming that your http requests
results in some kml that includes a polyline then personally I would
build an array containing each line and then just work out the closest
distance to each one from my current location every x seconds or y
feet travelled.

If you are further than a certain distance (which you have to decide)
from ALL of the lines then you know that the user has taken a detour
and you should simply resubmit a new routing request starting at your
current location and ending at the original location.

unless your kml has hundreds of polylines I'm not sure I'd even bother
optimize the algorithm - just brute force it.

I would be a little careful of what your app does though: you might
want to read the Maps TOS license restrictions carefully to make sure
you stay within them.

On Nov 29, 9:49 pm, James Black <planiturth...@gmail.com> wrote:
> Hello,
>   I am working on a navigation program and I have two things that could
> make my program better.
>
> 1. How can I find alternate routes.
>
>   I use this url currently:http://maps.google.com/maps?f=d&hl=en&saddr=xxx,zzz&daddr=yyy,www&ie=...
>
> 2. How can I tell when the user takes a detour from the path on the
> MathOverlay, so I can get a new route for them?
>
> Thank you.
>
> --
> "I know that you believe you understand what you think I said, but I'm not
> sure you realize that what you heard is not what I meant."
> - Robert McCloske

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