[GIS] Linestring in OpenLayers doesn’t draw

linestringopenlayers

I don't understand why my code doesn't work. If the map is displayed, the line is never drawn:

<script>
var long_deb = -1.28627;
var lat_deb = 43.49829;
var long_fin = -1.29394;
var lat_fin = 43.49858;
var attribution = new ol.control.Attribution({
  collapsible: false
});

var map = new ol.Map({
  controls: ol.control.defaults({ attribution: false }).extend([attribution]),
  target: 'map',
  view: new ol.View({
    center: ol.proj.fromLonLat([long_deb, lat_deb]),
    zoom: 15
  })
});
var layer = new ol.layer.Tile({
  source: new ol.source.OSM()
});
map.addLayer(layer);
var linestring = new ol.geom.LineString([[long_deb, lat_deb], [long_fin, lat_fin]], 'XY');
var lineString_feature = new ol.Feature ( {
    geometry: linestring
});
var layerLine = new ol.layer.Vector({
  source: new ol.source.Vector( {
    features: [ lineString_feature]
  })
});
map.addLayer(layerLine);
console.log(
    "lineString coordinates", linestring.getCoordinates(), 
    "extent", linestring.getExtent(), 
    "layout", linestring.getLayout());

var longueur =linestring.getLength();
console.log("longueur", longueur);
</script>

and the console message (log) : 

lineString coordinates Array [ Array[2], Array[2] ] extent Array [ -1.29394, 43.49829, -1.28627, 43.49858 ] layout XY
longueur 0.007675480440988747

Any idea?

Best Answer

I've found the reason : it's a projection's problem. To resolve it :

function transform_geometry(element) {
  var current_projection = new ol.proj.Projection({code: "EPSG:4326"});
  var new_projection = layer.getSource().getProjection();

  element.getGeometry().transform(current_projection, new_projection);
}
var features = [lineString_feature];
var layerLine = new ol.layer.Vector({
  source: new ol.source.Vector( {
    features: features
  })
});
features.forEach(transform_geometry);
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