PolylineCollection

new Cesium.PolylineCollection(options)

A renderable collection of polylines.


Example polylines


Polylines are added and removed from the collection using PolylineCollection#add and PolylineCollection#remove.
Performance:

For best performance, prefer a few collections, each with many polylines, to many collections with only a few polylines each. Organize collections so that polylines with the same update frequency are in the same collection, i.e., polylines that do not change should be in one collection; polylines that change every frame should be in another collection; and so on.

参数名称 类型 描述信息
options object 可选 Object with the following properties:
参数名称 类型 默认值 描述信息
modelMatrix Matrix4 Matrix4.IDENTITY 可选 The 4x4 transformation matrix that transforms each polyline from model to world coordinates.
debugShowBoundingVolume boolean false 可选 For debugging only. Determines if this primitive's commands' bounding spheres are shown.
show boolean true 可选 Determines if the polylines in the collection will be shown.
使用示例:
// Create a polyline collection with two polylines
const polylines = new Cesium.PolylineCollection();
polylines.add({
  positions : Cesium.Cartesian3.fromDegreesArray([
    -75.10, 39.57,
    -77.02, 38.53,
    -80.50, 35.14,
    -80.12, 25.46]),
  width : 2
});

polylines.add({
  positions : Cesium.Cartesian3.fromDegreesArray([
    -73.10, 37.57,
    -75.02, 36.53,
    -78.50, 33.14,
    -78.12, 23.46]),
  width : 4
});
参考:

成员(属性)

debugShowBoundingVolume : boolean

This property is for debugging only; it is not for production use nor is it optimized.

Draws the bounding sphere for each draw command in the primitive.

默认值: false
Returns the number of polylines in this collection. This is commonly used with PolylineCollection#get to iterate over all the polylines in the collection.
The 4x4 transformation matrix that transforms each polyline in this collection from model to world coordinates. When this is the identity matrix, the polylines are drawn in world coordinates, i.e., Earth's WGS84 coordinates. Local reference frames can be used by providing a different transformation matrix, like that returned by Transforms.eastNorthUpToFixedFrame.
默认值: Matrix4.IDENTITY
Determines if polylines in this collection will be shown.
默认值: true

方法

Creates and adds a polyline with the specified initial properties to the collection. The added polyline is returned so it can be modified or removed from the collection later.
Performance:

After calling add, PolylineCollection#update is called and the collection's vertex buffer is rewritten - an O(n) operation that also incurs CPU to GPU overhead. For best performance, add as many polylines as possible before calling update.

参数名称 类型 描述信息
options object 可选 A template describing the polyline's properties as shown in Example 1.
返回值:
The polyline that was added to the collection.
Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
使用示例:
// Example 1:  Add a polyline, specifying all the default values.
const p = polylines.add({
  show : true,
  positions : ellipsoid.cartographicArrayToCartesianArray([
           Cesium.Cartographic.fromDegrees(-75.10, 39.57),
           Cesium.Cartographic.fromDegrees(-77.02, 38.53)]),
  width : 1
});
参考:

contains(polyline)boolean

Determines if this collection contains the specified polyline.
参数名称 类型 描述信息
polyline Polyline The polyline to check for.
返回值:
true if this collection contains the polyline, false otherwise.
参考:
Destroys the WebGL resources held by this object. Destroying an object allows for deterministic release of WebGL resources, instead of relying on the garbage collector to destroy this object.

Once an object is destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception. Therefore, assign the return value (undefined) to the object as done in the example.
Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
使用示例:
polylines = polylines && polylines.destroy();
参考:
Returns the polyline in the collection at the specified index. Indices are zero-based and increase as polylines are added. Removing a polyline shifts all polylines after it to the left, changing their indices. This function is commonly used with PolylineCollection#length to iterate over all the polylines in the collection.
Performance:

If polylines were removed from the collection and PolylineCollection#update was not called, an implicit O(n) operation is performed.

参数名称 类型 描述信息
index number The zero-based index of the polyline.
返回值:
The polyline at the specified index.
Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
使用示例:
// Toggle the show property of every polyline in the collection
const len = polylines.length;
for (let i = 0; i < len; ++i) {
  const p = polylines.get(i);
  p.show = !p.show;
}
参考:
Returns true if this object was destroyed; otherwise, false.

If this object was destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception.
返回值:
true if this object was destroyed; otherwise, false.
参考:

remove(polyline)boolean

Removes a polyline from the collection.
Performance:

After calling remove, PolylineCollection#update is called and the collection's vertex buffer is rewritten - an O(n) operation that also incurs CPU to GPU overhead. For best performance, remove as many polylines as possible before calling update. If you intend to temporarily hide a polyline, it is usually more efficient to call Polyline#show instead of removing and re-adding the polyline.

参数名称 类型 描述信息
polyline Polyline The polyline to remove.
返回值:
true if the polyline was removed; false if the polyline was not found in the collection.
Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
使用示例:
const p = polylines.add(...);
polylines.remove(p);  // Returns true
参考:
Removes all polylines from the collection.
Performance:

O(n). It is more efficient to remove all the polylines from a collection and then add new ones than to create a new collection entirely.

Throws:
  • DeveloperError : This object was destroyed, i.e., destroy() was called.
使用示例:
polylines.add(...);
polylines.add(...);
polylines.removeAll();
参考:
Called when Viewer or CesiumWidget render the scene to get the draw commands needed to render this primitive.

Do not call this function directly. This is documented just to list the exceptions that may be propagated when the scene is rendered:

Throws:
  • RuntimeError : Vertex texture fetch support is required to render primitives with per-instance attributes. The maximum number of vertex texture image units must be greater than zero.