Geometry instancing allows one
Geometry
object to be positions in several
different locations and colored uniquely. For example, one BoxGeometry
can
be instanced several times, each with a different modelMatrix
to change
its position, rotation, and scale.
Name | Type | Description | ||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
options |
Object |
Object with the following properties:
|
Example:
// Create geometry for a box, and two instances that refer to it.
// One instance positions the box on the bottom and colored aqua.
// The other instance positions the box on the top and color white.
const geometry = Cesium.BoxGeometry.fromDimensions({
vertexFormat : Cesium.VertexFormat.POSITION_AND_NORMAL,
dimensions : new Cesium.Cartesian3(1000000.0, 1000000.0, 500000.0)
});
const instanceBottom = new Cesium.GeometryInstance({
geometry : geometry,
modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 1000000.0), new Cesium.Matrix4()),
attributes : {
color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.AQUA)
},
id : 'bottom'
});
const instanceTop = new Cesium.GeometryInstance({
geometry : geometry,
modelMatrix : Cesium.Matrix4.multiplyByTranslation(Cesium.Transforms.eastNorthUpToFixedFrame(
Cesium.Cartesian3.fromDegrees(-75.59777, 40.03883)), new Cesium.Cartesian3(0.0, 0.0, 3000000.0), new Cesium.Matrix4()),
attributes : {
color : Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.AQUA)
},
id : 'top'
});
See:
Members
Per-instance attributes like
ColorGeometryInstanceAttribute
or ShowGeometryInstanceAttribute
.
Geometry
attributes varying per vertex; these attributes are constant for the entire instance.
-
Default Value:
undefined
geometry : Geometry
The geometry being instanced.
-
Default Value:
undefined
User-defined object returned when the instance is picked or used to get/set per-instance attributes.
-
Default Value:
undefined
See:
modelMatrix : Matrix4
The 4x4 transformation matrix that transforms the geometry from model to world coordinates.
When this is the identity matrix, the geometry is 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
.
-
Default Value:
Matrix4.IDENTITY