如何从POINT（“.........”）绘制线串？

Question

我收到了这个Openlayer问题。

我试图从一些物体中获得一堆点数。我相信这不应该是困难的。

我正在将st_astext传递给WKT阅读器以创建一个Openlayers.Geometry.Point()要素，以添加到将保存所有行的初始图层。但这似乎不起作用。谁能看到我做错了什么？

//Routes for each bridge? 
vesselPosition = new OpenLayers.Layer.Vector('Vessels');
var wkt = new OpenLayers.Format.WKT();


$.ajax({
url: "/ajax/getPositions",
dataType: 'json',
success: function(result) {

for (var reportID in result) {
    //Store the object at hand.
    var data = result[reportID];


    //Get all the positions and print them onto the vesselpoisition layer. 
    var positions = data.positions;

    var listOfPoints = new Array();
    for (var index in positions) {
        var positionData = positions[index];
        var point= wkt.read(positionData.st_astext);

        listOfPoints.push(point.geometry);
    }

    var pointmap = new OpenLayers.Geometry.LineString({points:listOfPoints});

    vesselPosition.addFeatures(pointmap);

};
}
});

Answer 1

OpenLayers.Geometry.LineString需要参数的点数组，而不是对象： http://dev.openlayers.org/docs/files/OpenLayers/Geometry/LineString-js.html#OpenLayers.Geometry.LineString.OpenLayers.Geometry.LineString

答案：投影问题：

point.geometry.transform(
  new OpenLayers.Projection("EPSG:4326"),
  new OpenLayers.Projection("EPSG:900913")
);

所以试试

var pointmap = new OpenLayers.Geometry.LineString(listOfPoints);

也要注意

vesselPosition.addFeatures(pointmap);

addFeatures（）需要特征，而不是参数的几何。使用：

vesselPosition.addFeatures(new OpenLayers.Feature.Vector(pointmap));

出于测试目的，您可以绘制单个点来映射：

var point= wkt.read(positionData.st_astext);
vesselPosition.addFeatures(point);

另外，检查vesselPosition.features.length以确定是否有任何功能。