Hi Curt
Yes, as I recall (and I will dig into my code as soon as I pay bills) a
copy is constructed. So you need to walk through the points in the line
itself and find the one that matches the one you want to change (I gave
them all ids). THEN change it, THEN redraw the line. If you are doing
a lot of lines or points, do them all then redraw the layer.
Michael
On 4/12/2012 9:36 AM, Curtis Olson wrote:
Hi Michael (and everyone else who replied),
Thanks for your quick replies. I'm working on this some more today
and have some follow up questions.
I define my point list in the global scope:
var route_points = new Array();
Then I populate this array with a few points.
Finally I can build the structures and add the result to a layer so I
can see it (and I do see the result.)
lineString = new OpenLayers.Geometry.LineString(route_points);
route_vector = new OpenLayers.Feature.Vector(lineString,null,home_style);
routeLayer.addFeatures( route_vector );
Later I go back and change the location of a point in my route_list
array of points.
route_points[2].lon = newlon;
route_points[2].lat = newlat;
But nothing changes on screen. (for what it's worth, I can recreate
all these structures and add them as a new layer to my map and I do
see the new points in their correct locations, but it's as a new
feature along with the old -- I'm hoping to be able to simply modify
the old structure rather than having to create a new (potentially
large/complex) structure each iteration.
I am wondering if the lineString or the Vector constructors use a copy
of the upstream structure rather than a pointer to the structure? In
that case changing my original structure would have no effect.
I wouldn't mind using accessor functions to find the actual data
point, but as I look through the class definitions and inheritance, I
don't see any way to get back to the original point array when
starting from a Vector() or a LineString()?
I'm probably missing something stupid or easy, but I'm just not seeing
it? Am I on the right track or missing by a mile?
Thanks,
Curt.
On Wed, Apr 11, 2012 at 2:22 PM, Michael <[email protected]
<mailto:[email protected]>> wrote:
Both are doable. You need to do a little digging to be sure you
are pointing to the correct point when you either change its
lonlat or delete it. Then you need to redraw the line.
In my application, I maintained a separate array pointing to the
points in my line. Possibly not the most efficient, but it worked.
Michael
On 4/11/2012 12:08 PM, Curtis Olson wrote:
Hi,
I've begun my plunge into openlayers and have a number of things
working, but I've run into a question that I haven't been able to
answer for myself from the docs and the mailing list archives.
I am building a map that will live track an object (for example:
my aircraft location as I fly in the FlightGear flight simulator.)
I would like to leave a trail behind myself showing my recent
path (say for the past 10 seconds or the past 10 minutes.) I am
imagining a LineString where I can insert new points at one end
and remove points from the other end -- as my position updates.
I could create an entirely new LineString and Vector and add that
to my layer 10x a second (removing the old feature), but I was
hoping I could just build the linestring once, add it too a layer
once, and from then on just modify the linestring structure.
Is something like this possible or am I barking up the wrong tree?
I have another sort of similar situation where I may want to
additionally modify the point locations of some of the points in
the linestring (based on external data coming from the flight
simulator.) In otherwords I want to reshape the linestring by
adjusting the locations of individual points. Is anything like
this possible?
I've been hunting through the examples and the documentation and
haven't stumbled on the appropriate magic yet.
Any tips or pointers or nudges for an openlayers newbie?
Thanks,
Curt.
--
Curtis Olson:
http://www.atiak.com - http://aem.umn.edu/~uav/
<http://aem.umn.edu/%7Euav/>
http://www.flightgear.org - http://gallinazo.flightgear.org
_______________________________________________
Users mailing list
[email protected] <mailto:[email protected]>
http://lists.osgeo.org/mailman/listinfo/openlayers-users
_______________________________________________
Users mailing list
[email protected] <mailto:[email protected]>
http://lists.osgeo.org/mailman/listinfo/openlayers-users
--
Curtis Olson:
http://www.atiak.com - http://aem.umn.edu/~uav/
<http://aem.umn.edu/%7Euav/>
http://www.flightgear.org - http://gallinazo.flightgear.org
_______________________________________________
Users mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/openlayers-users
_______________________________________________
Users mailing list
[email protected]
http://lists.osgeo.org/mailman/listinfo/openlayers-users
