/*
 *      @(#)InterpolationControl.java 1.0 99/02/14 23:00:00
 *
 * Copyright (c) 1999. All Rights Reserved.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY
 * IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR
 * NON-INFRINGEMENT, ARE HEREBY EXCLUDED. WE SHALL NOT BE
 * LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
 * OR DISTRIBUTING THE SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR ITS
 * LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT,
 * INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER
 * CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF
 * OR INABILITY TO USE SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * This software is not designed or intended for use in on-line control of
 * aircraft, air traffic, aircraft navigation or aircraft communications; or in
 * the design, construction, operation or maintenance of any nuclear
 * facility. Licensee represents and warrants that it will not use or
 * redistribute the Software for such purposes.
 *
 * @Author: Dr. Richard Parent
 * @Author: Kovalan Muniandy
 *
 * Provides ease-in ease-out implementation discussed in the Chapter 4. Using
 * this object, one could control the speed along which an interpolation
 * proceeds.
 *
 */

public class InterpolationControl {
    public static double ease( double t ) {
         return (( Math.sin( t*Math.PI - Math.PI/2.0 ) + 1 ) / 2.0);
    }

    public static double ease( double t, double t1, double t2 ) {
        double e1 = (t1 * 2)/Math.PI;     // distance after t1 acceleration
        double e2 = (1 - t2)*2/Math.PI;   // distance after (1-t2) deceleration

        double rt, nt, s;

        if (t < t1) {               // if in accelaration stage
            nt = t/t1;              // fraction into accelaration
            s = Math.sin( -Math.PI/2.0 + nt*Math.PI/2.0 )
                   + 1;             // use sin quadrant for acceleration
            rt = s*e1;              // distance after s
        }
        else if (t > t2) {
            nt = (t - t2)/(1.0 - t2);   // fraction into deceleration
            s = Math.sin( nt*Math.PI/2.0 );  // use sine quadrant for accerleration
            rt = e1 + (t2 - t1) + s*e2; // distance after s
        }
        else {
            rt = e1 + t - t1;   // distance after t
        }

        rt = (rt / (e1 + (t2 - t1) + e2));
        return (rt);
    }

    /*
    public static double parabolicEase( double t, double a, double b ) {
        double v0, a1, a2;

        v0 = 2.0/(1 + b - a);

        if ( t &
    }
    */
}