Animating a marker on a section of a polyline

[Rob]

I have a polyline from A to B and I'm trying to animate a marker
moving along a section of the line (between two points - essentially I
want to show a vehicle moving along part of a route). Using v3_epoly
I've been able to animate from start to finish, but not a subset of
the route.

What I thought I could do is find the distance along the route of the
first marker/latlng, then do the same with the second and animate
between the two distances, but I can't find a way of getting the
distance along the polyline of a given latlng.

Can anyone give any pointers?

Thanks in advance!

[Chris Broadfoot]

Here's some code I hacked up a while ago:

http://broady.github.com/maps-examples/points-along-line/along-directions.html

Chris

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[Rossko]

> What I thought I could do is find the distance along the route of the
> first marker/latlng, then do the same with the second and animate
> between the two distances, but I can't find a way of getting the
> distance along the polyline of a given latlng.

You might use the GetPointAtDistance() method of v3_epoly

[geoco...@gmail.com]

Perhaps if you give a link to your map where you tried to do that, we
could see where you went wrong.

If you are using v3_epoly to animate it the whole length, you should
be able to use v3_epoly to find your start and end points.

-- Larry

[Rob]

I was hoping to find a more efficient approach but what you suggested
did the trick. I traverse the polyline once from start to finish, at
each stage checking whether the current lat/lng is also a marker's
location - if it is then I store the distance as part of the marker
object. Then the animation is just a case of several more
GetPointAtDistance() calls, with the value of distance bounded by the
two markers.

Thank you for your help.