mirror of
https://github.com/jiawanlong/Cesium-Examples.git
synced 2025-11-04 09:14:17 +00:00
294 lines
14 KiB
HTML
294 lines
14 KiB
HTML
<!DOCTYPE html>
|
||
<html>
|
||
<head>
|
||
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=0" />
|
||
<meta name="apple-mobile-web-app-capable" content="yes" />
|
||
<title>动画渲染专题</title>
|
||
<link href='./css/bootstrap.min.css' rel='stylesheet' />
|
||
<link href='./css/bootstrap-responsive.min.css' rel='stylesheet' />
|
||
<link href='./css/sm-extend.css' rel='stylesheet' />
|
||
<link href='./css/sm-doc.css' rel='stylesheet' />
|
||
</head>
|
||
<body data-spy="scroll" data-target=".subnav" data-offset="50">
|
||
<!--导航条-->
|
||
<div class="navbar navbar-fixed-top" id="navbar">
|
||
|
||
</div>
|
||
<div id='container' class='container'>
|
||
<div class='page-header'>
|
||
<h1 style="margin-top: 2%">客户端高性能矢量渲染专题</h1>
|
||
<hr />
|
||
<h2>一、高性能矢量渲染图层Vector类简介</h2>
|
||
<p>
|
||
SuperMap iClient for JavaScript 提供的 Vector 类支持采用 HTML5 的 Canvas
|
||
元素渲染矢量数据，并且提供了对渲染要素的添加、删除和选择操作，
|
||
从而为大数据量的矢量数据在无插件的 HTML 文档中，平滑、流畅的呈现，提供了新的解决方案。
|
||
</p>
|
||
<h2>二、高性能矢量渲染图层 Vector 类的使用说明</h2>
|
||
<p> Vector 类用 addFeatures、removeFeatures、removeAllFeatures、
|
||
redraw、getFeatureBy、 getFeatureById、getFeatureByFid、 getFeaturesByAttribute
|
||
等方法实现对要素的添加、删除、获取，方法的具体介绍和详细的使用说明请参见《API文档》，
|
||
下面以具体实例---<strong>车辆监控系统</strong>说明 Vector 的使用方法：
|
||
</p>
|
||
<p> 长春市某公交公司现有797辆车在28条公交
|
||
线路上正常运作运送乘客，为了满足车辆安防和调度的需要， 现对797辆车进行实时监控，
|
||
进而达到降低运营成本、提高服务水平、提高企业 收益的目的。此实例通过使用 Vector 类的接口实现了
|
||
对大量车辆的实时在线查询和更新功能。
|
||
</p>
|
||
<h3>2.1、查询功能</h3>
|
||
<p>
|
||
电子地图上实时显示797辆车，公交公司管理部门可以远程监控所有车辆，具体实现方法如下：
|
||
</p>
|
||
<p>
|
||
(1).初始化两个图层 vectorLayer、vectorLayerCars，一个作为公交车路线图层，一个作为公交车图层。
|
||
</p>
|
||
<pre>
|
||
//初始化公交车路线图层
|
||
vectorLayer = new SuperMap.Layer.Vector("Vector Layer", {
|
||
renderers: ["Canvas"],
|
||
styleMap: new SuperMap.StyleMap({"default": styleLine})
|
||
});
|
||
//初始化公交车图层
|
||
vectorLayerCars = new SuperMap.Layer.Vector("Vector Layer Cars", {
|
||
renderers: ["Canvas2"],
|
||
styleMap: new SuperMap.StyleMap({"default": stylePoint})
|
||
});
|
||
//为 vectorLayerCars 添加一个选择控件。
|
||
select = new SuperMap.Control.SelectFeature(vectorLayerCars, {
|
||
onSelect: onFeatureSelect,
|
||
onUnselect: onFeatureUnselect
|
||
}
|
||
);
|
||
map.addControl(select);
|
||
//要素被选中时调用此函数
|
||
function onFeatureSelect(feature) {
|
||
selecedtBus = feature;
|
||
popup = new SuperMap.Popup("chicken",
|
||
selecedtBus.geometry.getBounds().getCenterLonLat(),
|
||
new SuperMap.Size(300,42),
|
||
"<div style='font-size:.8em; opacity: 0.8'><p>公交线路：" + selecedtBus.line.num + "路" +
|
||
"</p><p>当前位置：" + selecedtBus.geometry.x + "，" + selecedtBus.geometry.y + "</p></div>", null, true);
|
||
selecedtBus.popup = popup;
|
||
map.addPopup(popup);
|
||
}
|
||
//清除要素时调用此函数
|
||
function onFeatureUnselect(feature) {
|
||
map.removePopup(feature.popup);
|
||
feature.popup.destroy();
|
||
feature.popup = null;
|
||
selecedtBus = null;
|
||
}
|
||
</pre>
|
||
<p>
|
||
(2).定义查询的公交车路线，通过 SQL 查询方法查询公交路线,通过监听对 QueryBySQLService 支持的
|
||
两个从服务端返回结果事件 processCompleted 、processFailed，获取查询公交路线结果。
|
||
</p>
|
||
<pre>
|
||
//定义查询公交线路
|
||
function queryBySQL() {
|
||
//清除当前图层所有feature要素
|
||
vectorLayer.removeAllFeatures();
|
||
var queryParam, queryBySQLParams, queryBySQLService;
|
||
//声明查询参数
|
||
queryParam = new SuperMap.REST.FilterParameter({
|
||
name: "BusLine@Changchun#1",
|
||
attributeFilter: "SmID > 0"}
|
||
),
|
||
//声明 SQL 查询参数，将 queryParam 赋给 queryBySQLParams
|
||
queryBySQLParams = new SuperMap.REST.QueryBySQLParameters({
|
||
queryParams: [queryParam]
|
||
}),
|
||
//声明 SQL 服务对象
|
||
queryBySQLService = new SuperMap.REST.QueryBySQLService(url, {
|
||
eventListeners: {
|
||
"processCompleted": processCompleted,
|
||
"processFailed": processFailed
|
||
}
|
||
});
|
||
//向服务端发送请求执行查询
|
||
queryBySQLService.processAsync(queryBySQLParams);
|
||
}
|
||
</pre>
|
||
<p>
|
||
(3). 定义 QueryBySQLService 的监听对象，用于显示公交路线图层和公家车图层，实现过程中
|
||
需要先分别定义一个公交路线的数组和公交车的数组，然后通过公交路线节点模拟公交车，
|
||
实例化公交车的运行方向和位置，最后添加公交车路线图层和公交车图层。
|
||
</p>
|
||
<pre>
|
||
function processCompleted(queryEventArgs) {
|
||
var i, j, feature,
|
||
result = queryEventArgs.result;
|
||
features = [];
|
||
cars = [];
|
||
orientation = 1;
|
||
if (result && result.recordsets) {
|
||
for (i=0; i<result.recordsets.length; i++) {
|
||
if (result.recordsets[i].features) {
|
||
for (j=0; j<result.recordsets[i].features.length; j++) {
|
||
feature = result.recordsets[i].features[j];
|
||
feature.style = null;
|
||
feature.num = j;
|
||
features.push(feature);
|
||
for(var k = 0, len = feature.geometry.components.length; k < len; k++) {
|
||
//创建公交车对象
|
||
var car = new SuperMap.Feature.Vector(feature.geometry.components[k].clone());
|
||
//定义公交车的 style
|
||
car.style = {pointRadius: 10, stroke: false};
|
||
var cargeometry = car.geometry;
|
||
//定义公交车基本信息,包括公交车的路线、速度和速度向量、当前节
|
||
//点位置和下一结点位置、通过速度向量计算的旋转角度、移动步数
|
||
car.line = feature;
|
||
car.orientation = orientation;
|
||
car.currentIndex = k;
|
||
if(feature.geometry.components[car.currentIndex + car.orientation]) {
|
||
car.nextPoint = feature.geometry.components[k + car.orientation];
|
||
var dx = car.nextPoint.x - cargeometry.x;
|
||
var dy = car.nextPoint.y - cargeometry.y;
|
||
var distance = Math.sqrt(dx * dx + dy * dy);
|
||
car.speed = parseInt(Math.random() * 5 + 2) * car.orientation;
|
||
if(car.speed == 0) {car.speed == 10};
|
||
car.moves = distance / car.speed;
|
||
car.vx = dx / car.moves;
|
||
car.vy = dy / car.moves;
|
||
var angle = Math.atan2(dx, dy);
|
||
car.style.rotate = angle;
|
||
//分配不同的公交车图片
|
||
if (Math.abs(car.speed < 4)){
|
||
car.style.externalGraphicSource = car1;
|
||
}
|
||
if (Math.abs(car.speed) >= 4 && Math.abs(car.speed < 5)){
|
||
car.style.externalGraphicSource = car2;
|
||
}
|
||
if (Math.abs(car.speed >= 5)){
|
||
car.style.externalGraphicSource = car3;
|
||
}
|
||
car.stop = false;
|
||
}else{
|
||
car.stop = true;
|
||
car.style.externalGraphicSource = car3;
|
||
}
|
||
orientation *= -1;
|
||
cars.push(car);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
}
|
||
//将公交路线绘制到公交路线图层上
|
||
vectorLayer.addFeatures(features);
|
||
//将公交车绘制公交车图层上
|
||
vectorLayerCars.addFeatures(cars);
|
||
}
|
||
</pre>
|
||
<p>显示效果图如下所示：</P>
|
||
<div class="pageImage"><img src="./images/bus.png" /></div>
|
||
<h3>2.2大量车辆实时在线更新功能 </h3>
|
||
<p>
|
||
公交公司管理部门监控某一时间段内797辆车的运行状态 , 电子地图上显示每辆车每30秒的位置变化情况，实现代码如下：
|
||
</p>
|
||
<p>
|
||
（1）开始实施监控，通过公交车的基本信息（如速度，定位信息）改变其位置，实施方法为先全部
|
||
清除(removeAllFeatures)显示公交车的图层，再定义公交车的属性信息(方向、速度等)，
|
||
最后将改变后的公交车数组通过 addFeatures 方法加入至公交车图层。
|
||
</p>
|
||
<pre>
|
||
//开始监控
|
||
function monitor() {
|
||
document.getElementById("monitor").onclick = "";
|
||
if(selecedtBus) {
|
||
map.removePopup(selecedtBus.popup);
|
||
}
|
||
vectorLayerCars.removeAllFeatures();
|
||
redraw = false;
|
||
for(var i =0, len = cars.length; i < len; i++) {
|
||
var car = cars[i];
|
||
var cargeometry = car.geometry;
|
||
if(!car.stop) {
|
||
if(car.moves < 1) {
|
||
cargeometry.x = car.nextPoint.x;
|
||
cargeometry.y = car.nextPoint.y;
|
||
//更新公交车的信息
|
||
var feature = car.line;
|
||
car.currentIndex += car.orientation;
|
||
if(feature.geometry.components[car.currentIndex + car.orientation]) {
|
||
car.nextPoint = feature.geometry.components[car.currentIndex + car.orientation];
|
||
var dx = car.nextPoint.x - cargeometry.x;
|
||
var dy = car.nextPoint.y - cargeometry.y;
|
||
var distance = Math.sqrt(dx * dx + dy * dy);
|
||
car.moves = Math.abs(distance / car.speed);
|
||
car.vx = dx / car.moves;
|
||
car.vy = dy / car.moves;
|
||
var angle = Math.atan2(dx, dy);
|
||
car.style.rotate = angle;
|
||
}else{
|
||
car.stop = true;
|
||
car.style.fillColor = "rgb(150,150,150)";
|
||
}
|
||
}else{
|
||
cargeometry.x += car.vx;
|
||
cargeometry.y += car.vy;
|
||
car.moves--;
|
||
}
|
||
}
|
||
//只要有车移动就需要重绘。
|
||
if(!car.stop) {
|
||
redraw = true;
|
||
}
|
||
}
|
||
//将公交车绘制到公交车图层上
|
||
vectorLayerCars.addFeatures(cars);
|
||
if(selecedtBus) {
|
||
//将选中的公交车的信息添加到地图上
|
||
vectorLayerCars.selectedFeatures.push(selecedtBus);
|
||
popup = new SuperMap.Popup("chicken",
|
||
selecedtBus.geometry.getBounds().getCenterLonLat(),
|
||
new SuperMap.Size(300,42), "<div style='font-size:.8em; opacity: 0.8'><p>公交线路：" +
|
||
selecedtBus.line.num + "路" +
|
||
"</p><p>当前位置：" + selecedtBus.geometry.x + "，" + selecedtBus.geometry.y + "</p></div>",
|
||
null, true);
|
||
selecedtBus.popup = popup;
|
||
map.addPopup(popup);
|
||
}
|
||
}
|
||
</pre>
|
||
<p>（2）通过监听公交车图层的 feature 添加完成事件(addFeaturesCompelte)，
|
||
以实时调用 clearFeatures 方法实现公交车的动态监控。
|
||
</p>
|
||
<pre>
|
||
function addFeaturesCompelte(args) {
|
||
if(redraw) {
|
||
timerid = setTimeout(monitor, 50);
|
||
}
|
||
}
|
||
</pre>
|
||
<p>（3） 通过 onclick 事件停止监控。
|
||
</p>
|
||
<pre>
|
||
//停止监控
|
||
function stopMonitor() {
|
||
window.clearTimeout(timerid);
|
||
document.getElementById("monitor").onclick = monitor;
|
||
redraw = false;
|
||
}
|
||
</pre>
|
||
<h2>三、专题小结</h2>
|
||
<p>以上车辆监控实例通过高性能矢量渲染 Vector 类实现了对大量车辆的在线查询和
|
||
实时更新功能，满足了用户需求的同时，也带给用户平滑、流畅的视觉效果。
|
||
</p>
|
||
<p>通过实例也验证了高性能矢量绘制图层 Vector 类在大量数据显示、
|
||
实时更新等功能上的优异性能和流畅稳定的呈现，
|
||
为用户提供了客户端大量动态数据展示的解决方案。
|
||
</p>
|
||
</div>
|
||
<div class='footer'>
|
||
<p>版权所有 © 2000-2016 JWL</p>
|
||
</div>
|
||
</div>
|
||
<script src='./js/jquery.js'></script>
|
||
<script src='./js/bootstrap.js'></script>
|
||
<script src="./js/navbar.js"></script>
|
||
<script src="./js/GoTop.js" id="js_gotop"></script>
|
||
</body>
|
||
</html>
|