1package aurelienribon.tweenengine.paths;
2
3import aurelienribon.tweenengine.TweenPath;
4
5/**
6 * @author Aurelien Ribon | http://www.aurelienribon.com/
7 */
8public class CatmullRom implements TweenPath {
9	@Override
10	public float compute(float t, float[] points, int pointsCnt) {
11		int segment = (int) Math.floor((pointsCnt-1) * t);
12		segment = Math.max(segment, 0);
13		segment = Math.min(segment, pointsCnt-2);
14
15		t = t * (pointsCnt-1) - segment;
16
17		if (segment == 0) {
18			return catmullRomSpline(points[0], points[0], points[1], points[2], t);
19		}
20
21		if (segment == pointsCnt-2) {
22			return catmullRomSpline(points[pointsCnt-3], points[pointsCnt-2], points[pointsCnt-1], points[pointsCnt-1], t);
23		}
24
25		return catmullRomSpline(points[segment-1], points[segment], points[segment+1], points[segment+2], t);
26	}
27
28	private float catmullRomSpline(float a, float b, float c, float d, float t) {
29		float t1 = (c - a) * 0.5f;
30		float t2 = (d - b) * 0.5f;
31
32		float h1 = +2 * t * t * t - 3 * t * t + 1;
33		float h2 = -2 * t * t * t + 3 * t * t;
34		float h3 = t * t * t - 2 * t * t + t;
35		float h4 = t * t * t - t * t;
36
37		return b * h1 + c * h2 + t1 * h3 + t2 * h4;
38	}
39}
40