[OpenLayers-Users] Question on using multiple layers in different projections

[christopher.schmidt at nokia.com]

On Jun 30, 2010, at 7:02 PM, ext Stephen Woodbridge wrote:

> Hi all,
> 
> I have an OL app setup the is using epsg4326 and everything it fine.
> It has a mapserver base layer and a vector overlay with markers and 
> another with lines.
> 
> I have been asked to add Google as an additional base layer.
> 
> So my understanding is that the map object will take on the projection 
> of the base layer when you switch between them.
> 
> I have few questions:
> 
> 1. I assume that the vector features are not transformed when the base 
> layer is switched? Is this true? Which probably means I need to cycle 
> through the features and transform them to the base layers projection 
> something like:
> 
> map.events.register('changebaselayer', map, function(evt, element) {
>     var fromProj = map.getUnit()=='m'?epsg4326:epsg900913;
>     for (var i=0, var len=layer.features.length; i<len; i++)
>         layer.features[i].geometry.transform(fromProj, 
> map.getProjectionObject());
>     layer.redraw();
> });

Yes.

> 
> 2. I have a WKT parser object. It need to reproject the features based 
> on the current base layer. Can I change the internalProjection on base 
> layer change like:
> 
> parser.internalProjection = map.getProjectionObject();

That should work.

-- Chris