declare namespace pc {
    /**
     * @static
     * @readOnly
     * @name pc.DISTANCE_LINEAR
     * @type String
     * @description Linear distance model
     */
    const DISTANCE_LINEAR = 'linear';

    /**
     * @static
     * @readonly
     * @type String
     * @name pc.DISTANCE_INVERSE
     * @description Inverse distance model
     */
    const DISTANCE_INVERSE = 'inverse';

    /**
     * @static
     * @readonly
     * @type String
     * @name pc.DISTANCE_EXPONENTIAL
     * @description Exponential distance model
     */
    const DISTANCE_EXPONENTIAL = 'exponential';
}