activateGizmos( isActive ) {

		const gizmoX = this._gizmos.children[ 0 ];
		const gizmoY = this._gizmos.children[ 1 ];
		const gizmoZ = this._gizmos.children[ 2 ];

		if ( isActive ) {

			gizmoX.material.setValues( { opacity: 1 } );
			gizmoY.material.setValues( { opacity: 1 } );
			gizmoZ.material.setValues( { opacity: 1 } );

		} else {

			gizmoX.material.setValues( { opacity: 0.6 } );
			gizmoY.material.setValues( { opacity: 0.6 } );
			gizmoZ.material.setValues( { opacity: 0.6 } );

		}

	}
Makes rotation gizmos more or less visible.

@param {boolean} isActive - If set to `true`, gizmos are more visible.