java地图中如何让物体回到起点

Question

我想做一些像公交车跟踪这样的东西，它绕着一个每秒移动 2 米回到起点的多边形。每秒对象（？）点坐标。

而且我什至不知道如何开始。请帮助我。

多边形代码：

    function initMap() {
        map = new google.maps.Map(document.getElementById("map"), {
            zoom: 12,
            center: { lat: 0.5164426, lng: 101,4574499 },
            mapTypeId: "terrain",
        });
        
        const triangleCoords = [
            { lat: 0.5022181713704478, lng: 101.41882830662435 },
            { lat: 0.4975231087415325, lng: 101.39433139688956 },
            { lat: 0.5103834896305101, lng: 101.39412725597509 },
            { lat: 0.5169157367830446, lng: 101.39923077883651 },
            { lat: 0.5350835135799168, lng: 101.4035177380401 },
            { lat: 0.5348793815517918, lng: 101.41984901119662 },
        ];
        
        const bermudaTriangle = new google.maps.Polygon({
            paths: triangleCoords,
            strokeColor: "#0000FF",
            strokeOpacity: 1,
            strokeWeight: 2,
            fillColor: "#FF6633",
            fillOpacity: 0.35,
        });
        
        bermudaTriangle.setMap(map);
        bermudaTriangle.addListener("click", showArrays);
        infoWindow = new google.maps.InfoWindow();

基本上如何从 lat：0.5022181713704478，lng：101.41882830662435 返回到 lat：0.5022181713704478，lng：101.41882830662435 显着

我的预期：http://www.geocodezip.com/v3_animate_marker_directions.html 但它有 6 点陈述并且不断移动

Answer 1

您发布的代码有几个问题：

在 map center 上的 lng 之后没有 :：`

center: { lat: 0.5164426, lng 101,4574499 },

应该是：

center: { lat: 0.5164426, lng: 101,4574499 },

在 PolygonOptions

fillColor: "#FF6633"

中的PolygonOptionspanths应该是paths
为了与my example保持一致，你需要一个Polyline（而不是一个Polygon），这意味着你需要添加最后一个点来完成路径：

  const triangleCoords = [{
      lat: 0.5022181713704478,
      lng: 101.41882830662435
    },
    {
      lat: 0.4975231087415325,
      lng: 101.39433139688956
    },
    {
      lat: 0.5103834896305101,
      lng: 101.39412725597509
    },
    {
      lat: 0.5169157367830446,
      lng: 101.39923077883651
    },
    {
      lat: 0.5350835135799168,
      lng: 101.4035177380401
    },
    {
      lat: 0.5348793815517918,
      lng: 101.41984901119662
    },
    { // duplicate of first point
      lat: 0.5022181713704478,
      lng: 101.41882830662435
    },
  ];

proof of concept fiddle

为防止地图中心改变，去掉改变中心的代码（[=28=一个实例，map.panTo两个实例）：
fiddle where map center not modified

要保持标记在循环中盘旋，请更改“结束”条件以重新启动动画，方法是调用 animate(0):

function animate(d) {
  if (d > eol) {
    map.panTo(polyline.getPath().getAt(polyline.getPath().getLength() - 1));
    marker.setPosition(polyline.getPath().getAt(polyline.getPath().getLength() - 1));
    // continuous loop
    animate(0);
    return;
  }

live example

代码片段：

var polyline, marker;

function initMap() {
  addEpolyFunc();
  map = new google.maps.Map(document.getElementById("map"), {
    zoom: 12,
    center: {
      lat: 0.5164426,
      lng: 101.4574499
    },
    mapTypeId: "terrain",
  });

  const triangleCoords = [{
      lat: 0.5022181713704478,
      lng: 101.41882830662435
    },
    {
      lat: 0.4975231087415325,
      lng: 101.39433139688956
    },
    {
      lat: 0.5103834896305101,
      lng: 101.39412725597509
    },
    {
      lat: 0.5169157367830446,
      lng: 101.39923077883651
    },
    {
      lat: 0.5350835135799168,
      lng: 101.4035177380401
    },
    {
      lat: 0.5348793815517918,
      lng: 101.41984901119662
    },
    {
      lat: 0.5022181713704478,
      lng: 101.41882830662435
    },
  ];

  const bermudaTriangle = new google.maps.Polygon({
    paths: triangleCoords,
    strokeColor: "#0000FF",
    strokeOpacity: 1,
    strokeWeight: 2,
    fillColor: "#FF6633",
    fillOpacity: 0.35,
  });

  bermudaTriangle.setMap(map);
  infoWindow = new google.maps.InfoWindow();
  polyline = new google.maps.Polyline({
    // map: map,
    path: triangleCoords,
    strokeColor: "#0000FF",
    strokeOpacity: 1,
    strokeWeight: 2,
  });
  marker = new google.maps.Marker({
    position: polyline.getPath().getAt(0),
    map: map
  })

  startAnimation();
}
var step = 50; // 5; // metres
var tick = 100; // milliseconds
var eol;
var k = 0;
var stepnum = 0;
var speed = "";
var lastVertex = 1;


//=============== animation functions ======================
function updatePoly(d) {
  // Spawn a new polyline every 20 vertices, because updating a 100-vertex poly is too slow
  if (poly2.getPath().getLength() > 20) {
    poly2 = new google.maps.Polyline([polyline.getPath().getAt(lastVertex - 1)]);
  }

  if (polyline.GetIndexAtDistance(d) < lastVertex + 2) {
    if (poly2.getPath().getLength() > 1) {
      poly2.getPath().removeAt(poly2.getPath().getLength() - 1)
    }
    poly2.getPath().insertAt(poly2.getPath().getLength(), polyline.GetPointAtDistance(d));
  } else {
    poly2.getPath().insertAt(poly2.getPath().getLength(), polyline.getPath().getAt(polyline.getPath().getLength() - 1));
  }
}


function animate(d) {
  if (d > eol) {
    map.panTo(polyline.getPath().getAt(polyline.getPath().getLength() - 1));
    marker.setPosition(polyline.getPath().getAt(polyline.getPath().getLength() - 1));
    // continuous loop
    animate(0);
    return;
  }
  var p = polyline.GetPointAtDistance(d);
  map.panTo(p);
  marker.setPosition(p);
  updatePoly(d);
  timerHandle = setTimeout("animate(" + (d + step) + ")", tick);
}


function startAnimation() {
  eol = google.maps.geometry.spherical.computeLength(polyline.getPath());
  map.setCenter(polyline.getPath().getAt(0));
  poly2 = new google.maps.Polyline({
    path: [polyline.getPath().getAt(0)],
    strokeColor: "#0000FF",
    strokeWeight: 10
  });
  setTimeout("animate(50)", 2000); // Allow time for the initial map display
}

function addEpolyFunc() {
  //=============== ~animation funcitons =====================
  // from epoly_v3.js
  // modified to use geometry library for length of line segments
  // === A method which returns the Vertex number at a given distance along the path ===
  // === Returns null if the path is shorter than the specified distance ===
  google.maps.Polyline.prototype.GetIndexAtDistance = function(metres) {
    // some awkward special cases
    if (metres == 0) return this.getPath().getAt(0);
    if (metres < 0) 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;
    }
    return i;
  }
  // === 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.Polyline.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);
  }
  // === A method which returns the length of a path in metres ===
  google.maps.Polyline.prototype.Distance = function() {
    var dist = 0;
    for (var i = 1; i < this.getPath().getLength(); i++) {
      dist += google.maps.geometry.spherical.computeDistanceBetween(this.getPath().getAt(i), this.getPath().getAt(i - 1));
    }
    return dist;
  }
}

/* Always set the map height explicitly to define the size of the div
       * element that contains the map. */

#map {
  height: 100%;
}


/* Optional: Makes the sample page fill the window. */

html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

<!DOCTYPE html>
<html>

<head>
  <title>Simple Polygon</title>
  <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
  <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&callback=initMap&libraries=geometry&v=weekly" defer></script>
  <!-- jsFiddle will insert css and js -->
</head>

<body>
  <div id="map"></div>
</body>

</html>

java地图中如何让物体回到起点

How to make a object back to the start point in java map

html

google-maps

gis

google-maps-markers