百度地图画直线时有个BUG，取三个坐标点测试，
var point1=new BMap.Point(113.33765,23.150435);
var point2=new BMap.Point(113.347655,23.160435);
var point3=new BMap.Point(113.357655,23.170435);
var point2=new BMap.Point(113.347655,23.160435);
var point3=new BMap.Point(113.357655,23.170435);
默认Point1到point3是从低纬度到高纬度，由于维度排序呈现递增趋势，也就是说，Point1是开始点，Point3是结束点，那么展现的地图的三个点能正常画出连线。如下图：
var polyline = new BMap.Polyline([
point1,
point2,
point3
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
point1,
point2,
point3
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
现在我们把专递的序列顺序调换为point1->point3->point2,那么就出现问题，直线不能完整的绘画，只连接的两个点，这是因为百度地图的Polyline对象内为对转入的坐标点按其坐标位置
进行排序导致的，测试如下：
var polyline = new BMap.Polyline([
point1,
point3,
point2
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
point1,
point3,
point2
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
现在我们来测试折线是否也存在这个问题，首先我们也取同上三个坐标点，把point2经度向东移动稍微调下，使得三个点不再一条直线上。
var point1=new BMap.Point(113.33765,23.150435);//保持不变
var point2=new BMap.Point(113.347655,23.160435);//经度向东移动0.02为：（113.347655,23.160435）->(113.367655,23.160435)
var point3=new BMap.Point(113.357655,23.170435);//保持不变
绘图顺序为：
var point2=new BMap.Point(113.347655,23.160435);//经度向东移动0.02为：（113.347655,23.160435）->(113.367655,23.160435)
var point3=new BMap.Point(113.357655,23.170435);//保持不变
绘图顺序为：
var polyline = new BMap.Polyline([
point1,
point3,
point2
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
point1,
point3,
point2
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
效果如下：
为了同直线做对比，我们把坐标顺序调整为：
var polyline = new BMap.Polyline([
point1,
point2,
point3
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
point1,
point2,
point3
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
我们仔细观察会发现，同样的调整了坐标序列顺序，虽然折线绘画出来了所有连线（若是直线则会出现断线情况），但是只要调整了序列顺序，绘画出来的图形就会发生变化。那么我们也许会疑问，
到底百度绘画折线的规律是什么？分析上面的列子，我们总结出Polyline对象画线的规律为：
1.直线：（简单理解为从开始点到结束点）
1.1 同经度时，从低纬度到高纬度。
1.2 同纬度时，从小经度度到大经度。
2.折线：（不分经纬度大小高低，只是按坐标序列先后依次将各个点连接）
==================================================测试代码=====================================
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style type="text/css">
body, html,#allmap { 100%;height: 100%;overflow: hidden;margin:0;}
#l-map{height:100%;78%;float:left;border-right:2px solid #bcbcbc;}
#r-result{height:100%;20%;float:left;}
</style>
<script type="text/javascript" src="http://api.map.baidu.com/api?v=1.4"></script>
<title>折线</title>
</head>
<body>
<div id="allmap"></div>
</body>
</html>
<script type="text/javascript">
var map = new BMap.Map("allmap");
var point = new BMap.Point(113.347655,23.160435);
map.centerAndZoom(point, 15);
var point1=new BMap.Point(113.33765,23.150435);
var point2=new BMap.Point(113.347655,23.160435);
var point3=new BMap.Point(113.357655,23.170435);
var marker1 = new BMap.Marker(point1); // 创建标注
var marker2 = new BMap.Marker(point2); // 创建标注
var marker3 = new BMap.Marker(point3); // 创建标注
map.addOverlay(marker1);
map.addOverlay(marker2);
map.addOverlay(marker3);
var polyline = new BMap.Polyline([
point1,
point2,
point3
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
map.addOverlay(polyline);
var view = map.getViewport([
point1,
point2,
point3
]);
map.centerAndZoom(view.center, view.zoom);
</script>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style type="text/css">
body, html,#allmap { 100%;height: 100%;overflow: hidden;margin:0;}
#l-map{height:100%;78%;float:left;border-right:2px solid #bcbcbc;}
#r-result{height:100%;20%;float:left;}
</style>
<script type="text/javascript" src="http://api.map.baidu.com/api?v=1.4"></script>
<title>折线</title>
</head>
<body>
<div id="allmap"></div>
</body>
</html>
<script type="text/javascript">
var map = new BMap.Map("allmap");
var point = new BMap.Point(113.347655,23.160435);
map.centerAndZoom(point, 15);
var point1=new BMap.Point(113.33765,23.150435);
var point2=new BMap.Point(113.347655,23.160435);
var point3=new BMap.Point(113.357655,23.170435);
var marker1 = new BMap.Marker(point1); // 创建标注
var marker2 = new BMap.Marker(point2); // 创建标注
var marker3 = new BMap.Marker(point3); // 创建标注
map.addOverlay(marker1);
map.addOverlay(marker2);
map.addOverlay(marker3);
var polyline = new BMap.Polyline([
point1,
point2,
point3
], {strokeColor:"blue", strokeWeight:6, strokeOpacity:0.5});
map.addOverlay(polyline);
var view = map.getViewport([
point1,
point2,
point3
]);
map.centerAndZoom(view.center, view.zoom);
</script>