CODEWITHSUNDEEP
openlayers-3
interwebjill
interwebjill

Reputation: 950

Adding multiple layers in OpenLayers 3

I am populating OpenLayer 3 features by loading the array multipointCoords from multiple GeoJSON features separately in turn. I reuse the following function each time I load a GeoJSON feature:

   function makeLineString(multipointCoords) {

        var trackSource = new ol.source.Vector();

        var lineString = new ol.geom.LineString([ // create a linestring geometry from the GeoJSON data for the tracks
            ol.proj.fromLonLat(multipointCoords[0][0])
        ]);

        var trackFeature = new ol.Feature({ // create a feature with the linestring geometry
            geometry: lineString
        });

        trackSource.addFeature(trackFeature); // add the feature to the sourc

        var trackLayer = new ol.layer.Vector({ // create a layer with that source
            source: trackSource
        });
        map.addLayer(trackLayer); // add the layer to the map
};

Am I loading all of the features, regardless of which data set they came from, onto the same layer or are multiple "trackLayers" being created? Is there a way to address the layers and features by which data set they came from?

Upvotes: 0

Views: 4165

Answers (1)

Alvin Lindstam
Alvin Lindstam

Reputation: 3142

Yes, you are creating a new source (with a single feature) and a new layer for each invocation of makeLineString.

You generally want to put all features from a given dataset into the same source (and consequently the same layer). The most common way to do so is to configure a source with an url and a format representing the remote data set.

An example of loading all features from a GeoJSON file into the same source and displaying them in a single layer from the official examples:

var vector = new ol.layer.Vector({
  source: new ol.source.Vector({
    url: 'data/geojson/countries.geojson',
    format: new ol.format.GeoJSON(),
    wrapX: false
  })
});

Upvotes: 1

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