constructor (parent) {
    super(parent)
    this['material.side'] = this['material.shadowSide'] = DoubleSide
  }
A simple planar circle, laying along the x-z plane, facing the positive y axis, centered on the origin.
The `radius` property is an alias to uniform `scaleX` and `scaleZ`. Set `scaleX/Y/Z` individually if
you need non-uniform scaling.
The `detail` property allows selecting a LOD; its values can be 'low', 'medium', or 'high'.
To control the material, see {@link MeshFacade}.