一种在地图中处理曲线的通用方法

一种在地图中处理曲线的通用方法

本文分享一种可以用于处理曲线的算法,是本人在百度地图开源库基础上改造的,可以用于其他地图场景中处理点数据,只要两个以上的点,就可以得到平滑的曲线。例如小程序,将处理后得到的点赋值给polyline的points即可。

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function getCurveByTwoPoints(obj1, obj2) {
if (!obj1 || !obj2) {
return null
}
var B1 = function (x) {
return 1 - 2 * x + x * x
};
var B2 = function (x) {
return 2 * x - 2 * x * x
};
var B3 = function (x) {
return x * x
};
curveCoordinates = [];
var count = 30;
var isFuture = false;
var t, h, h2, lat3, lng3, j, t2;
var LnArray = [];
var i = 0;
var inc = 0;
if (typeof(obj2) == "undefined") {
if (typeof(curveCoordinates) != "undefined") {
curveCoordinates = []
}
return
}
var lat1 = parseFloat(obj1.lat);
var lat2 = parseFloat(obj2.lat);
var lng1 = parseFloat(obj1.lng);
var lng2 = parseFloat(obj2.lng);
if (lng2 > lng1) {
if (parseFloat(lng2 - lng1) > 180) {
if (lng1 < 0) {
lng1 = parseFloat(180 + 180 + lng1)
}
}
}
if (lng1 > lng2) {
if (parseFloat(lng1 - lng2) > 180) {
if (lng2 < 0) {
lng2 = parseFloat(180 + 180 + lng2)
}
}
}
j = 0;
t2 = 0;
if (lat2 == lat1) {
t = 0;
h = lng1 - lng2
} else {
if (lng2 == lng1) {
t = Math.PI / 2;
h = lat1 - lat2
} else {
t = Math.atan((lat2 - lat1) / (lng2 - lng1));
h = (lat2 - lat1) / Math.sin(t)
}
}
if (t2 == 0) {
t2 = (t + (Math.PI / 5))
}
h2 = h / 2;
lng3 = h2 * Math.cos(t2) + lng1;
lat3 = h2 * Math.sin(t2) + lat1;
for (i = 0; i < count + 1; i++) {
curveCoordinates.push(
{
lng: (lng1 * B1(inc) + lng3 * B2(inc)) + lng2 * B3(inc),
lat: (lat1 * B1(inc) + lat3 * B2(inc) + lat2 * B3(inc))
}
);
inc = inc + (1 / count)
}
return curveCoordinates
}

function getCurvePoints(points) {
var curvePoints = [];
for (var i = 0; i < points.length - 1; i++) {
var p = getCurveByTwoPoints(points[i], points[i + 1]);
if (p && p.length > 0) {
curvePoints = curvePoints.concat(p)
}
}
return curvePoints
}

let trackPoints = [{lng:113.281, lat:29.203}, {lng:113.567, lat:29.301}]

let convertPoints = getCurvePoints(trackPoints)

console.log(convertPoints)

最后再给一个微信小程序应用实例

map.wxml

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// 举个小程序应用的例子
<map id="map" longitude="113.324520" latitude="23.099994" scale="14" controls="{{controls}}" bindcontroltap="controltap" markers="{{markers}}" bindmarkertap="markertap" polyline="{{polyline}}" bindregionchange="regionchange" show-location style="width:100vw;height:100vh;"></map>

map.js

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Page({
data: {
markers: [{
iconPath: "/resources/marker.png",
id: 0,
latitude: 23.099994,
longitude: 113.324520,
width: 50,
height: 50
}],
polyline: [],
controls: [{
id: 1,
iconPath: '/resources/location.png',
position: {
left: 0,
top: 300 - 50,
width: 50,
height: 50
},
clickable: true
}]
},
onLoad() {
this.setData({
polyline:[{
points: this.getCurvePoints([{ lng: 113.3245211, lat: 23.10229 }, { lng: 113.324520, lat: 23.21229 }]),
color: "#FF0000DD",
width: 2
}]
})
},
regionchange(e) {
console.log(e.type)
},
markertap(e) {
console.log(e.markerId)
},
controltap(e) {
console.log(e.controlId)
},
getCurveByTwoPoints(obj1, obj2) {
if (!obj1 || !obj2) {
return null
}
var B1 = function (x) {
return 1 - 2 * x + x * x
};
var B2 = function (x) {
return 2 * x - 2 * x * x
};
var B3 = function (x) {
return x * x
};
var curveCoordinates = [];
var count = 30;
var isFuture = false;
var t, h, h2, lat3, lng3, j, t2;
var LnArray = [];
var i = 0;
var inc = 0;
if (typeof (obj2) == "undefined") {
if (typeof (curveCoordinates) != "undefined") {
curveCoordinates = []
}
return
}
var lat1 = parseFloat(obj1.lat);
var lat2 = parseFloat(obj2.lat);
var lng1 = parseFloat(obj1.lng);
var lng2 = parseFloat(obj2.lng);
if (lng2 > lng1) {
if (parseFloat(lng2 - lng1) > 180) {
if (lng1 < 0) {
lng1 = parseFloat(180 + 180 + lng1)
}
}
}
if (lng1 > lng2) {
if (parseFloat(lng1 - lng2) > 180) {
if (lng2 < 0) {
lng2 = parseFloat(180 + 180 + lng2)
}
}
}
j = 0;
t2 = 0;
if (lat2 == lat1) {
t = 0;
h = lng1 - lng2
} else {
if (lng2 == lng1) {
t = Math.PI / 2;
h = lat1 - lat2
} else {
t = Math.atan((lat2 - lat1) / (lng2 - lng1));
h = (lat2 - lat1) / Math.sin(t)
}
}
if (t2 == 0) {
t2 = (t + (Math.PI / 5))
}
h2 = h / 2;
lng3 = h2 * Math.cos(t2) + lng1;
lat3 = h2 * Math.sin(t2) + lat1;
for (i = 0; i < count + 1; i++) {
curveCoordinates.push(
{
longitude: (lng1 * B1(inc) + lng3 * B2(inc)) + lng2 * B3(inc),
latitude: (lat1 * B1(inc) + lat3 * B2(inc) + lat2 * B3(inc))
}
);
inc = inc + (1 / count)
}
return curveCoordinates
},
getCurvePoints(points) {
var curvePoints = [];
for (var i = 0; i < points.length - 1; i++) {
var p = this.getCurveByTwoPoints(points[i], points[i + 1]);
if (p && p.length > 0) {
curvePoints = curvePoints.concat(p)
}
}
return curvePoints
}
})

献上效果图:

小程序地图曲线


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