Geometry - CesiumJS API 文档

new Cesium.Geometry(options)

带有形成顶点和可选索引数据的属性的几何表达式 defining primitives. Geometries and an Appearance, which describes the shading, can be assigned to a Primitive for visualization. A Primitive can 由许多不同的——在许多情况下——为性能而设置的几何图形.

Geometries can be transformed and optimized using functions in GeometryPipeline.

Name Type Description

options

object

下列属性的对象 :

Name	Type	Default	Description
`attributes`	GeometryAttributes		属性,构成几何的顶点.
`primitiveType`	PrimitiveType	`PrimitiveType.TRIANGLES`	optional The type of primitives in the geometry.
`indices`	Uint16Array \| Uint32Array		optional 确定几何中原始的可选索引数据.
`boundingSphere`	BoundingSphere		optional 完全包围几何的可选边框 .

Example:

// Create geometry with a position attribute and indexed lines.
const positions = new Float64Array([
  0.0, 0.0, 0.0,
  7500000.0, 0.0, 0.0,
  0.0, 7500000.0, 0.0
]);

const geometry = new Cesium.Geometry({
  attributes : {
    position : new Cesium.GeometryAttribute({
      componentDatatype : Cesium.ComponentDatatype.DOUBLE,
      componentsPerAttribute : 3,
      values : positions
    })
  },
  indices : new Uint16Array([0, 1, 1, 2, 2, 0]),
  primitiveType : Cesium.PrimitiveType.LINES,
  boundingSphere : Cesium.BoundingSphere.fromVertices(positions)
});

Demo:

Geometry and Appearances Demo

See:

Members

attributes : GeometryAttributes

属性,构成几何的顶点. 此对象中的每个属性对应 a 包含属性数据的 GeometryAttribute .

属性总是被存储在几何中非间断.

有保留属性名称有著名的语义学. 以下属性 are created by a Geometry (depending on the provided VertexFormat.

position - 3D vertex position. 64-bit floating-point (for precision). 3 components per attribute. See VertexFormat#position.
normal - Normal (normalized), commonly used for lighting. 32-bit floating-point. 3 components per attribute. See VertexFormat#normal.
st - 2D texture coordinate. 32-bit floating-point. 2 components per attribute. See VertexFormat#st.
bitangent - Bitangent (normalized), used for tangent-space effects like bump mapping. 32-bit floating-point. 3 components per attribute. See VertexFormat#bitangent.
tangent - Tangent (normalized), used for tangent-space effects like bump mapping. 32-bit floating-point. 3 components per attribute. See VertexFormat#tangent.

以下属性名称一般不由几何创建,而是添加 to a Geometry by a Primitive or GeometryPipeline functions to prepare 用于渲染的几何图形.

position3DHigh - High 32 bits for encoded 64-bit position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.
position3DLow - Low 32 bits for encoded 64-bit position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.
position2DHigh - High 32 bits for encoded 64-bit 2D (Columbus view) position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.
position2DLow - Low 32 bits for encoded 64-bit 2D (Columbus view) position computed with GeometryPipeline.encodeAttribute. 32-bit floating-point. 4 components per attribute.
color - RGBA color (normalized) usually from GeometryInstance#color. 32-bit floating-point. 4 components per attribute.
pickColor - RGBA color used for picking. 32-bit floating-point. 4 components per attribute.

Example:

geometry.attributes.position = new Cesium.GeometryAttribute({
  componentDatatype : Cesium.ComponentDatatype.FLOAT,
  componentsPerAttribute : 3,
  values : new Float32Array(0)
});

See:

boundingSphere : BoundingSphere|undefined

完全附着几何的可选边框。这是通常用于 culling.

Default Value: undefined

indices : Array|undefined

Optional index data that - along with Geometry#primitiveType - 确定几何中的原始物.

Default Value: undefined

primitiveType : PrimitiveType|undefined

The type of primitives in the geometry. This is most often PrimitiveType.TRIANGLES, 但可以根据具体的几何特征而变化.

Default Value: PrimitiveType.TRIANGLES

Methods

static Cesium.Geometry.computeNumberOfVertices(geometry) → number

计算几何中顶点的数量。运行时间为线性 ,而不是顶点数.

Name	Type	Description
`geometry`	Geometry	The geometry.

Returns:

几何中顶数.

Example:

const numVertices = Cesium.Geometry.computeNumberOfVertices(geometry);