Base class for all geometry creation utility classes that can be passed to 
GeometryInstance
for asynchronous geometry creation.
Methods
static Cesium.GeometryFactory.createGeometry(geometryFactory) → Geometry|undefined
    Returns a geometry.
    
| Name | Type | Description | 
|---|---|---|
| geometryFactory | GeometryFactory | A description of the circle. | 
Returns:
    The computed vertices and indices.
    
