GroundPolylinePrimitive - CesiumJS API 文档

new Cesium.GroundPolylinePrimitive(options)

A GroundPolylinePrimitive represents a polyline draped over the terrain or 3D Tiles in the Scene.

仅用于含有 GroundPolylineGeometry 的几何内存.

Name Type Description

options

object

optional 下列属性的对象 :

Name	Type	Default	Description
`geometryInstances`	Array \| GeometryInstance		optional 含有地表聚合物的几何结构
`appearance`	Appearance		optional The Appearance used to render the polyline. Defaults to a white color `Material` on a `PolylineMaterialAppearance`.
`show`	boolean	`true`	optional Determines if this primitive will be shown.
`interleave`	boolean	`false`	optional When `true`, geometry vertex attributes are interleaved, which can slightly improve rendering performance but increases load time.
`releaseGeometryInstances`	boolean	`true`	optional When `true`, the primitive does not keep a reference to the input `geometryInstances` to save memory.
`allowPicking`	boolean	`true`	optional When `true`, each geometry instance will only be pickable with `Scene#pick`. When `false`, GPU memory is saved.
`asynchronous`	boolean	`true`	optional Determines if the primitive will be created asynchronously or block until ready. If false initializeTerrainHeights() must be called first.
`classificationType`	ClassificationType	`ClassificationType.BOTH`	optional Determines whether terrain, 3D Tiles or both will be classified.
`debugShowBoundingVolume`	boolean	`false`	optional For debugging only. Determines if this primitive's commands' bounding spheres are shown.
`debugShowShadowVolume`	boolean	`false`	optional For debugging only. Determines if the shadow volume for each geometry in the primitive is drawn. Must be `true` on creation to have effect.

Example:

// 1. Draw a polyline on terrain with a basic color material

const instance = new Cesium.GeometryInstance({
  geometry : new Cesium.GroundPolylineGeometry({
     positions : Cesium.Cartesian3.fromDegreesArray([
         -112.1340164450331, 36.05494287836128,
         -112.08821010582645, 36.097804071380715
     ]),
     width : 4.0
  }),
  id : 'object returned when this instance is picked and to get/set per-instance attributes'
});

scene.groundPrimitives.add(new Cesium.GroundPolylinePrimitive({
  geometryInstances : instance,
  appearance : new Cesium.PolylineMaterialAppearance()
}));

// 2. Draw a looped polyline on terrain with per-instance color and a distance display condition.
// Distance display conditions for polylines on terrain are based on an approximate terrain height
// instead of true terrain height.

const instance2 = new Cesium.GeometryInstance({
  geometry : new Cesium.GroundPolylineGeometry({
     positions : Cesium.Cartesian3.fromDegreesArray([
         -112.1340164450331, 36.05494287836128,
         -112.08821010582645, 36.097804071380715,
         -112.13296079730024, 36.168769146801104
     ]),
     loop : true,
     width : 4.0
  }),
  attributes : {
     color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromCssColorString('green').withAlpha(0.7)),
     distanceDisplayCondition : new Cesium.DistanceDisplayConditionGeometryInstanceAttribute(1000, 30000)
  },
  id : 'object returned when this instance is picked and to get/set per-instance attributes'
});

scene.groundPrimitives.add(new Cesium.GroundPolylinePrimitive({
  geometryInstances : instance2,
  appearance : new Cesium.PolylineColorAppearance()
}));

Members

readonly allowPicking : boolean

When true, each geometry instance will only be pickable with Scene#pick. When false, GPU memory is saved.

Default Value: true

appearance : Appearance

The Appearance used to shade this primitive. Each geometry 实例以相同的外观遮蔽。一些外表,比如说 PolylineColorAppearance allow giving each instance unique properties.

Default Value: undefined

readonly asynchronous : boolean

确定是否创建几何实例并在网络工人上进行分批.

Default Value: true

classificationType : ClassificationType

确定是否对地形、3D平面或两者进行分类.

Default Value: ClassificationType.BOTH

debugShowBoundingVolume : boolean

此属性仅用于调试;不用于生产,也不优化.

绘制原始中每个绘图命令的边框.

Default Value: false

readonly debugShowShadowVolume : boolean

此属性仅用于调试;不用于生产,也不优化.

如果真实,则为原始中的每一几何绘制阴影音量.

Default Value: false

readonly geometryInstances : Array|GeometryInstance

用这个原始的几何学实例。这可能如果 NT 0 未定义 NT 1 如果 NT 4 is true when the primitive is constructed.

原始化后改变这个属性没有效果.

Default Value: undefined

readonly interleave : boolean

确定几何顶点属性是否互换,这可以略微改善渲染性能.

Default Value: false

readonly ready : boolean

确定原始的是否完整,是否准备制成. 如果这是 true, the primitive will be rendered the next time that GroundPolylinePrimitive#update is called.

readonly releaseGeometryInstances : boolean

When true, the primitive does not keep a reference to the input geometryInstances to save memory.

Default Value: true

show : boolean

确定是否将显示原始文件。这影响到所有几何原始中的例子.

Default Value: true

Methods

static Cesium.GroundPolylinePrimitive.initializeTerrainHeights() → Promise.<void>

初始化最小和最大地形高度. 只有您正在创建 GroundPolylinePrimitive synchronously.

Returns:

一旦地形高度升空承诺就能解决.

static Cesium.GroundPolylinePrimitive.isSupported(scene) → boolean

检查给定的 NT 0 是否支持 GroundPolyline Primmitives . GroundPolyline Primmitives需要支持WEBGL 深度纹理扩展.

Name	Type	Description
`scene`	Scene	目前的场景.

Returns:

当前场景是否支持 GroundPolyline Primmitives .

destroy()

Destroys the WebGL resources held by this object. Destroying an object allows for deterministic 释放 WebGL 资源,而不是依赖垃圾收集器来摧毁此对象.

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.

Example:

e = e && e.destroy();

See:

GroundPolylinePrimitive#isDestroyed

getGeometryInstanceAttributes(id) → object

Returns the modifiable per-instance attributes for a GeometryInstance.

Name	Type	Description
`id`	*	The id of the `GeometryInstance`.

Returns:

在属性格式中键入的数组, 如果无 id 实例, 则未定义 .

Throws:

DeveloperError : must call update before calling getGeometryInstanceAttributes.

Example:

const attributes = primitive.getGeometryInstanceAttributes('an id');
attributes.color = Cesium.ColorGeometryInstanceAttribute.toValue(Cesium.Color.AQUA);
attributes.show = Cesium.ShowGeometryInstanceAttribute.toValue(true);

isDestroyed() → boolean

如果此对象被销毁, 返回真实; 否则, 错误 .

If this object was destroyed, it should not be used; calling any function other than isDestroyed will result in a DeveloperError exception.

Returns:

true if this object was destroyed; otherwise, false.

See:

GroundPolylinePrimitive#destroy

update()

Called when Viewer or CesiumWidget render the scene to 获得使这个原始化所需的绘图命令.

不要直接调用此函数。记录下来的只是列出场景拍摄时可能宣传的例外情况:

Throws:

DeveloperError : For synchronous GroundPolylinePrimitives, you must call GroundPolylinePrimitives.initializeTerrainHeights() and wait for the returned promise to resolve.
DeveloperError : All GeometryInstances must have color attributes to use PolylineColorAppearance with GroundPolylinePrimitive.