01 
02 /*
03  *  JScripter Standard 1.0 - To Script In Java
04  *  Copyright (C) 2008-2011  J.J.Liu<jianjunliu@126.com> <http://www.jscripter.org>
05  *  
06  *  This program is free software: you can redistribute it and/or modify
07  *  it under the terms of the GNU Affero General Public License as published by
08  *  the Free Software Foundation, either version 3 of the License, or
09  *  (at your option) any later version.
10  *  
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU Affero General Public License for more details.
15  *  
16  *  You should have received a copy of the GNU Affero General Public License
17  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19 
20 package jsx.motion;
21 
22 import js.ArrayLike;
23 import jsx.core.ArrayLikes;
24 
25 /**
26  * <p>Defines motions by approximating sample data with the simplest linear interpolation.</p>
27  * 
28  * @author <a href="mailto:jianjunliu@126.com">J.J.Liu (Jianjun Liu)</a> at <a href="http://www.jscripter.org" target="_blank">http://www.jscripter.org</a>
29  */
30 public final class Linear extends Interpolator
31 {
32     /**
33      * <p>The typical constructor to construct a motion of this type.</p>
34      * @param values An array of sample data to be held by this object.
35      * @since 1.0
36      */
37     public Linear(ArrayLike<Number> values) {
38         super(values);
39     }
40 
41     /**
42      * <p>Gets the datum of a float number for the specified step.</p>
43      * @param i The step number. It must be within the number of steps previously initialized 
44      * with the method {@link Motion#init(int)}.
45      * @return The float datum for the <tt>i</tt>th step.
46      * @since 1.0
47      */
48     @Override
49     public final double get(int i) {
50         int n = ArrayLikes.length(values) - 1;
51         double x = ((double)n * i) / steps(this);
52         int j = x >= n ? n - 1 : x < 0 ? 0 : (int)x;
53         double y = values.get(j).doubleValue();
54         return y + (values.get(j + 1).doubleValue() - y) * (x - j);
55     }
56 }