Geometry

new Cesium.Geometry(options)
Core/Geometry.js 67

具有形成顶点的属性和可选索引数据的几何表示 定义原语。几何图形和Appearance，它描述了阴影， 可分配给Primitive进行可视化。Primitive罐 从许多异构（在许多情况下）几何图形创建以获得性能。

Geometries can be transformed and optimized using functions in GeometryPipeline.

Name Type Description
options Object 具有以下属性的对象：
Name Type Default Description
attributes GeometryAttributes 属性，组成几何体的顶点。
primitiveType PrimitiveType PrimitiveType.TRIANGLES optional 几何体中基本体的类型。
indices Uint16Array | Uint32Array optional 确定几何体中基本体的可选索引数据。
boundingSphere BoundingSphere optional 完全封闭几何体的可选边界球体。
Example:
// Create geometry with a position attribute and indexed lines.
var positions = new Float64Array([
  0.0, 0.0, 0.0,
  7500000.0, 0.0, 0.0,
  0.0, 7500000.0, 0.0
]);

var 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:
See:

Members

attributes : GeometryAttributes
Core/Geometry.js 120

属性，它构成几何体的顶点。此对象中的每个属性对应于 GeometryAttribute包含属性数据。

Attributes are always stored non-interleaved in a Geometry.

There are reserved attribute names with well-known semantics. The following attributes 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.

The following attribute names are generally not created by a Geometry, but are added to a Geometry by a Primitive or GeometryPipeline functions to prepare the geometry for rendering.

  • 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.
  • position3DHigh - 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.
Default Value: undefined
Example:
geometry.attributes.position = new Cesium.GeometryAttribute({
  componentDatatype : Cesium.ComponentDatatype.FLOAT,
  componentsPerAttribute : 3,
  values : new Float32Array(0)
});
See:

boundingSphere : BoundingSphere
Core/Geometry.js 153

完全封闭几何体的可选边界球体。这是 常用于扑杀。
Default Value: undefined

indices : Array
Core/Geometry.js 130

可选索引数据，连同Geometry#primitiveType- 确定几何体中的基本体。
Default Value: undefined

primitiveType : PrimitiveType
Core/Geometry.js 140

几何体中基本体的类型。通常是PrimitiveType.TRIANGLES， 但可以根据具体的几何结构而变化。
Default Value: undefined

Methods

static Cesium.Geometry.computeNumberOfVertices(geometry) → Number
Core/Geometry.js 182

计算几何体中的顶点数。运行时与 与顶点的数目无关。
Name Type Description
geometry Geometry 几何学。
Returns:
几何体中的顶点数。
Example:
var numVertices = Cesium.Geometry.computeNumberOfVertices(geometry);