A geometry representation with attributes forming vertices and optional index data
defining primitives. Geometries and an
Appearance
, which describes the shading,
can be assigned to a Primitive
for visualization. A Primitive
can
be created from many heterogeneous - in many cases - geometries for performance.
Geometries can be transformed and optimized using functions in GeometryPipeline
.
Name | Type | Description | ||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
options |
object |
Object with the following properties:
|
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:
See:
Members
Attributes, which make up the geometry's vertices. Each property in this object corresponds to a
GeometryAttribute
containing the attribute's data.
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. SeeVertexFormat#position
.normal
- Normal (normalized), commonly used for lighting. 32-bit floating-point. 3 components per attribute. SeeVertexFormat#normal
.st
- 2D texture coordinate. 32-bit floating-point. 2 components per attribute. SeeVertexFormat#st
.bitangent
- Bitangent (normalized), used for tangent-space effects like bump mapping. 32-bit floating-point. 3 components per attribute. SeeVertexFormat#bitangent
.tangent
- Tangent (normalized), used for tangent-space effects like bump mapping. 32-bit floating-point. 3 components per attribute. SeeVertexFormat#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 withGeometryPipeline.encodeAttribute
. 32-bit floating-point. 4 components per attribute.position3DLow
- Low 32 bits for encoded 64-bit position computed withGeometryPipeline.encodeAttribute
. 32-bit floating-point. 4 components per attribute.position2DHigh
- High 32 bits for encoded 64-bit 2D (Columbus view) position computed withGeometryPipeline.encodeAttribute
. 32-bit floating-point. 4 components per attribute.position2DLow
- Low 32 bits for encoded 64-bit 2D (Columbus view) position computed withGeometryPipeline.encodeAttribute
. 32-bit floating-point. 4 components per attribute.color
- RGBA color (normalized) usually fromGeometryInstance#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
An optional bounding sphere that fully encloses the geometry. This is
commonly used for culling.
-
Default Value:
undefined
Optional index data that - along with
Geometry#primitiveType
-
determines the primitives in the geometry.
-
Default Value:
undefined
primitiveType : PrimitiveType|undefined
The type of primitives in the geometry. This is most often
PrimitiveType.TRIANGLES
,
but can varying based on the specific geometry.
-
Default Value:
PrimitiveType.TRIANGLES
Methods
Computes the number of vertices in a geometry. The runtime is linear with
respect to the number of attributes in a vertex, not the number of vertices.
Name | Type | Description |
---|---|---|
geometry |
Geometry | The geometry. |
Returns:
The number of vertices in the geometry.
Example:
const numVertices = Cesium.Geometry.computeNumberOfVertices(geometry);