我已经在Here Map上绘制了几个标记和一个多边形对象,我想知道多边形和标记之间的距离。
我想知道多边形和标记之间的距离。我想知道距离多边形很近的标记。
Here Map有一个距离函数,但它只能计算两个标记之间的距离。
下面是我用来计算距离的函数。PaohaIsland.getGeometry().distance(yosmitePark.getGeometry())
哪儿 包头岛 是 标记 对象和 yosmitePark 是 多边形 对象
var map;
function loadMap(){
platform = new H.service.Platform({
'apikey': HEREMAP_KEY
});
// Obtain the default map types from the platform object:
var defaultLayers = platform.createDefaultLayers();
// Instantiate (and display) a map object:
map = new H.Map(
document.getElementById('mapContainer'),
defaultLayers.vector.normal.map,
{
center: { lat: 37.278419, lng: -119.674072,
pixelRatio: window.devicePixelRatio || 1 },
zoom: 8
}
);
// Enable the event system on the map instance:
var mapEvents = new H.mapevents.MapEvents(map);
var behavior = new H.mapevents.Behavior(mapEvents);
behavior.enable(H.mapevents.Behavior.WHEELZOOM);
}
function addPolygonToMap() {
var lineString2 = new H.geo.LineString();
lineString2.pushPoint({lat:37.278419,lng:-119.674072});
lineString2.pushPoint({lat:37.335224,lng:-119.30603});
lineString2.pushPoint({lat:37.529331,lng:-119.198914});
lineString2.pushPoint({lat:37.522789,lng:-118.99292});
lineString2.pushPoint({lat:37.627281,lng:-118.87207});
lineString2.pushPoint({lat:37.80978,lng:-119.053337});
lineString2.pushPoint({lat:38.01347,lng:-119.143982});
lineString2.pushPoint({lat:37.965851,lng:-119.770203});
lineString2.pushPoint({lat:37.898689,lng:-120.18219});
lineString2.pushPoint({lat:37.867802,lng:-120.341492});
lineString2.pushPoint({lat:37.746819,lng:-120.239861});
lineString2.pushPoint({lat:37.51844,lng:-120.07782});
lineString2.pushPoint({lat:37.278419,lng:-119.674072});
var yosmitePark = new H.map.Polygon(lineString2, {
style: {
strokeColor: '#829',
lineWidth: 8
}
});
map.addObject(yosmitePark);
var lakeMcClure = new H.map.Marker({
lat: 37.6373862,
lng: -120.3448606
});
lakeMcClure.setData("lakeMcClure");
var Stockton = new H.map.Marker({
lat: 37.9729404,
lng: -121.4419639
});
Stockton.setData("Stockton");
var Monolake = new H.map.Marker({
lat: 38.0067483,
lng: -119.1013779
});
Monolake.setData("Monolake");
var PaohaIsland = new H.map.Marker({
lat: 38.000514,
lng: -119.0416587
});
PaohaIsland.setData("PaohaIsland");
var WalkerLake = new H.map.Marker({
lat: 38.7010578,
lng: -118.878652
});
WalkerLake.setData("WalkerLake");
var Bakersfield = new H.map.Marker({
lat: 35.3208963,
lng: -119.1587737
});
Bakersfield.setData("Bakersfield");
var SanFrancisco = new H.map.Marker({
lat: 37.7576793,
lng: -122.5076405
});
SanFrancisco.setData("SanFrancisco");
map.addObjects([lakeMcClure,Stockton,Monolake,PaohaIsland,WalkerLake,Bakersfield,SanFrancisco]);
var mapObj = map.getObjects();
console.log(yosmitePark.getGeometry());
console.log(PaohaIsland.getGeometry().distance(yosmitePark.getGeometry()));
}
在API中没有方法来计算从点到多边形的距离。
为了达到这个目的,你可以计算从点到多边形外部LineString的每一段的距离,然后选择最小的计算值。
function distanceToGeoPolygon(geoPoint, geoPolygon) {
let lineString = geoPolygon.getExterior(),
minDistance = Infinity;
// check distance for each LineString segment of the polygon
for (let i = 0; i < lineString.getPointCount() - 1; i++) {
let segmentStart = lineString.extractPoint(i),
segmentEnd = lineString.extractPoint(i + 1),
distance = distanceToSegment(geoPoint, segmentStart, segmentEnd);
// set new min distance
if (distance <= minDistance) {
minDistance = distance;
}
}
return minDistance;
}
这里是计算点到线段距离的方法。
function distanceToSegment(point, segmentStart, segmentEnd) {
// first we find the intersecting point of line which
// crosses the given point and is vertical to segment (start - end)
let y0 = point.lat,
x0 = point.lng,
y1 = segmentStart.lat,
x1 = segmentStart.lng,
y2 = segmentEnd.lat,
x2 = segmentEnd.lng,
a = (y2 - y1) / (x2 - x1),
b = y1 - a * x1,
b0 = y0 + 1/a * x0,
xi = a * (b0 - b) / ((a * a) + 1),
yi = a * xi + b,
intersectingPoint = new H.geo.Point(yi, xi);
// if calculated intersecting point is within the segment,
// calculate distance between intersecting point and given point
if ( (xi > x1 && xi < x2 || xi > x2 && xi < x1) &&
(yi > y1 && yi < y2 || yi > y2 && yi < y1) ) {
return point.distance(intersectingPoint)
} else {
// else calculate distance between segment edges and given point
// and return the smaller one
return Math.min(point.distance(segmentStart), point.distance(segmentEnd));
}
}
test.这里是计算点到线段距离的方法:test:
// test: (result is 14359)
console.log(distanceToGeoPolygon(lakeMcClure.getGeometry(), yosmitePark.getGeometry()));
测试: 注: 上面的脚本对多边形内的点也返回正数。如果你不想要这样,你可以使用 H.Map#getObjectsWithin 来验证给定的标记对象(必须放在地图上)是否在地理多边形内(在你的情况下,我假设你不需要它)。
这里是工作原理 jsfiddle 例如:在点击Marker对象后,在控制台中记录距离。它在点击Marker对象后,在控制台记录距离。