在OpenLayers 3中动态地添加和删除轨道段 [英] Dynamically adding and removing segments from a track in OpenLayers 3

问题描述

我想用OpenLayers 3实时显示一条轨迹，最后如同蜗牛轨迹一样分散。

只需将新坐标附加到LineString就很容易。请参阅此示例。但是从行尾删除坐标看起来没有被API支持。

我应该怎么做？扩展LineString类是唯一的选择吗？或者应该为每个细分受众群使用单独的功能？

更新：

我用这个代码与ol-debug.js。但get / setFlatCoordinates不会在编译版本中导出。

  var flatCoordinates = geometry.getFlatCoordinates（）; （flatCoordinates&& flatCoordinates.length> 100）{
 //从数组$ b中移除第一个坐标元素$ b $ flatcoordinates.splice（0，geometry.getStride（） ）; 
 //以坐标元素作为参数调用推送
 Array.prototype.push.apply（flatCoordinates，coordinate）; 
 //更新坐标调用change（）
 geometry.setFlatCoordinates（geometry.getLayout（），flatCoordinates）; 
} 
 else {
 geometry.appendCoordinate（coordinate）; 
 
  

解决方案

appendCoordinate 方法是添加一个相当常见的用例的快捷方式坐标到LineString的末尾。要修改的几何形状与更多的控制权，与 setCoordinates设置你想要的坐标。

  var maxCoords = 100; 
 var coords = lineString.getCoordinates（）; //获得坐标数组
 coords.unshift（newCoord）; //添加到数组的开头
 if（coords.length> maxCoords）{
 coords.length = maxCoords; 
} 
 lineString.setCoordinates（coords）; 
  

I want to display a track in real-time with OpenLayers 3 which disolves at the end, just like a snails trail.

Only appending new coordinates to a LineString is easy. See this example. But removing coordinates from the end of the line does not seem to be supported by the API.

How should I go about that? Is extending the LineString class the only option? Or should I use a separate feature for each line segment?

Update:

I used this code with ol-debug.js. But get/setFlatCoordinates is not exported in the compiled version.

var flatCoordinates = geometry.getFlatCoordinates();  // not exported
if (flatCoordinates && flatCoordinates.length > 100) {
  // remove first coordinate elements from array
  flatCoordinates.splice(0, geometry.getStride());
  // call push with coordinate elements as arguments
  Array.prototype.push.apply(flatCoordinates, coordinate);
  // update coordinates calling change()
  geometry.setFlatCoordinates(geometry.getLayout(), flatCoordinates);
} 
else {
  geometry.appendCoordinate(coordinate);
}

解决方案

The appendCoordinate method is a shortcut for the fairly common use case of adding a coordinate to the end of a LineString. To modify geometries with more control, set your desired coordinates with setCoordinates.

var maxCoords = 100;
var coords = lineString.getCoordinates(); // get coordinate array
coords.unshift(newCoord); // add to beginning of array
if (coords.length > maxCoords) {
    coords.length = maxCoords;
}
lineString.setCoordinates(coords);

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