Question

目前，我使用Google地图和电子邮件在地图上绘制了线条。融合表利用Jquery＆amp; AJAX

我需要的是沿着一条线绘制一个点。我拥有的是

一个。开始协调样本39.793147，-86.238922

B中。完成协调样本39.799276，-86.238922

℃。从开始到绘图的距离点样本500米

d。（计算坐标）39.797797，-86.238922

所以我的问题是什么是最好的或者我有什么选择才能计算D. ...样本是具有相同经度的直线但实际上是Lat＆amp;长期将是不同的。

示例替代方案例如，开始39.793147，-86.238922结束39.801703，-86.237062或该行可能有多个点

例如

<LineString><coordinates>-86.238922,39.793147 -86.238922,39.797797 -86.238829,39.800122 -86.237062,39.801703</coordinates></LineString>

我希望我已经解释了我想要实现的目标。这可能是有可能得到这些点并在这两点之间绘制所需的距离吗？

期待任何想法或样本。非常感谢，总是

Answer 1

一个选项是使用Mike Williams' epoly library

中的.GetPointAtDistance函数

代码段

＆＃13;

var map;

function initialize() {
  map = new google.maps.Map(
    document.getElementById("map_canvas"), {
      center: new google.maps.LatLng(37.4419, -122.1419),
      zoom: 13,
      mapTypeId: google.maps.MapTypeId.ROADMAP
    });

  var lineString = [
    [-86.238922, 39.793147],
    [-86.238922, 39.797797],
    [-86.238829, 39.800122],
    [-86.237062, 39.801703]
  ];
  var path = [];
  var bounds = new google.maps.LatLngBounds();
  for (var i = 0; i < lineString.length; i++) {
    var pt = new google.maps.LatLng(lineString[i][1], lineString[i][0]);
    bounds.extend(pt);
    path.push(pt);
  }
  var polyline = new google.maps.Polyline({
    map: map,
    path: path
  });
  map.fitBounds(bounds);
  var sMark = new google.maps.Marker({
    position: {
      lat: lineString[0][1],
      lng: lineString[0][0]
    },
    map: map,
    title: "Start",
    icon: "http://www.google.com/mapfiles/markerS.png"
  });
  var mark = new google.maps.Marker({
    position: polyline.GetPointAtDistance(500),
    map: map,
    title: "500m"
  });

}
google.maps.event.addDomListener(window, "load", initialize);

/*********************************************************************\
*                                                                     *
* epolys.js                                          by Mike Williams *
* updated to API v3                                  by Larry Ross    *
*                                                                     *
* A Google Maps API Extension                                         *
*                                                                     *
* Adds various Methods to google.maps.Polygon and google.maps.Polyline *
* .GetPointAtDistance() returns a GLatLng at the specified distance   *
*                   along the path.                                   *
*                   The distance is specified in metres               *
*                   Reurns null if the path is shorter than that      *
*                                                                     *
***********************************************************************
*                                                                     *
*   This Javascript is provided by Mike Williams                      *
*   Blackpool Community Church Javascript Team                        *
*   http://www.blackpoolchurch.org/                                   *
*   http://econym.org.uk/gmap/                                        *
*                                                                     *
*   This work is licenced under a Creative Commons Licence            *
*   http://creativecommons.org/licenses/by/2.0/uk/                    *
*                                                                     *
***********************************************************************
*                                                                     *
* Version 1.1       6-Jun-2007                                        *
* Version 1.2       1-Jul-2007 - fix: Bounds was omitting vertex zero *
*                                add: Bearing                         *
* Version 1.3       28-Nov-2008  add: GetPointsAtDistance()           *
* Version 1.4       12-Jan-2009  fix: GetPointsAtDistance()           *
* Version 3.0       11-Aug-2010  update to v3                         *
*                                                                     *
\*********************************************************************/

// === A method which returns a GLatLng of a point a given distance along the path ===
// === Returns null if the path is shorter than the specified distance ===
google.maps.Polygon.prototype.GetPointAtDistance = function(metres) {
  // some awkward special cases
  if (metres == 0) return this.getPath().getAt(0);
  if (metres < 0) return null;
  if (this.getPath().getLength() < 2) return null;
  var dist = 0;
  var olddist = 0;
  for (var i = 1;
    (i < this.getPath().getLength() && dist < metres); i++) {
    olddist = dist;
    dist += google.maps.geometry.spherical.computeDistanceBetween(this.getPath().getAt(i), this.getPath().getAt(i - 1));
  }
  if (dist < metres) {
    return null;
  }
  var p1 = this.getPath().getAt(i - 2);
  var p2 = this.getPath().getAt(i - 1);
  var m = (metres - olddist) / (dist - olddist);
  return new google.maps.LatLng(p1.lat() + (p2.lat() - p1.lat()) * m, p1.lng() + (p2.lng() - p1.lng()) * m);
}

// === Copy all the above functions to GPolyline ===
google.maps.Polyline.prototype.GetPointAtDistance = google.maps.Polygon.prototype.GetPointAtDistance;

＆＃13;

html,
body,
#map_canvas {
  height: 100%;
  width: 100%;
  margin: 0px;
  padding: 0px
}

＆＃13;

<script src="https://maps.googleapis.com/maps/api/js?libraries=geometry,places"></script>
<div id="map_canvas"></div>

＆＃13;

计算从开始纬度/长坐标和完成纬度/长坐标的给定距离处的点的坐标

1 个答案: