declare namespace pc {

    /**
     * @enum pc.CURVE
     * @name pc.CURVE_LINEAR
     * @description A linear interpolation scheme.
     */
    const CURVE_LINEAR = 0;
    /**
     * @enum pc.CURVE
     * @name pc.CURVE_SMOOTHSTEP
     * @description A smooth step interpolation scheme.
     */
    const CURVE_SMOOTHSTEP = 1;
    /**
     * @enum pc.CURVE
     * @name pc.CURVE_CATMULL
     * @description A Catmull-Rom spline interpolation scheme.
     */
    const CURVE_CATMULL = 2;
    /**
     * @enum pc.CURVE
     * @name pc.CURVE_CARDINAL
     * @description A cardinal spline interpolation scheme.
     */
    const CURVE_CARDINAL = 3;

    /**
     * @name pc.Curve
     * @class A curve is a collection of keys (time/value pairs). The shape of the
     * curve is defined by its type that specifies an interpolation scheme for the keys.
     * @description Creates a new curve.
     * @param {Number[]} [data] An array of keys (pairs of numbers with the time first and
     * value second)
     * @property {Number} length The number of keys in the curve. [read only]
     */
    class Curve {
        constructor(data?: number[])

        length: number;

        /**
         * @function
         * @name pc.Curve#add
         * @description Add a new key to the curve.
         * @param {Number} time Time to add new key
         * @param {Number} value Value of new key
         * @returns {Number[]} [time, value] pair
         */
        add(time: number, value: number): number[];

        /**
         * @function
         * @name pc.Curve#get
         * @description Return a specific key.
         * @param {Number} index The index of the key to return
         * @returns {Number[]} The key at the specified index
         */
        get(index: number): number[];

        /**
         * @function
         * @name pc.Curve#sort
         * @description Sort keys by time.
         */
        sort(): void;

        /**
         * @function
         * @name pc.Curve#value
         * @description Returns the interpolated value of the curve at specified time.
         * @param {Number} time The time at which to calculate the value
         * @return {Number} The interpolated value
         */
        value(time: number): number;

        /**
         * @function
         * @name pc.Curve#clone
         * @description Returns a clone of the specified curve object.
         * @returns {pc.Curve} A clone of the specified curve
         */
        clone(): pc.Curve;
    }
}