001/**
002 *
003 * Copyright (c) 2014, the Railo Company Ltd. All rights reserved.
004 *
005 * This library is free software; you can redistribute it and/or
006 * modify it under the terms of the GNU Lesser General Public
007 * License as published by the Free Software Foundation; either 
008 * version 2.1 of the License, or (at your option) any later version.
009 * 
010 * This library is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013 * Lesser General Public License for more details.
014 * 
015 * You should have received a copy of the GNU Lesser General Public 
016 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
017 * 
018 **/
019package lucee.runtime.img.interpolation;
020
021public class Mitchell implements Interpolation
022{
023    public double f(double x) {
024        double b = 0.3333333333333333;
025        double c = 0.3333333333333333;
026        if (x < 0.0)
027            x = -x;
028        if (x < 1.0) {
029            x = ((12.0 - 9.0 * b - 6.0 * c) * (x * x * x)
030                 + (-18.0 + 12.0 * b + 6.0 * c) * x * x + (6.0 - 2.0 * b));
031            return x / 6.0;
032        }
033        if (x < 2.0) {
034            x = ((-1.0 * b - 6.0 * c) * (x * x * x)
035                 + (6.0 * b + 30.0 * c) * x * x + (-12.0 * b - 48.0 * c) * x
036                 + (8.0 * b + 24.0 * c));
037            return x / 6.0;
038        }
039        return 0.0;
040    }
041    
042    public double getSupport() {
043        return 2.0;
044    }
045}