/* * opsu! - an open-source osu! client * Copyright (C) 2014, 2015 Jeffrey Han * * opsu! is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * opsu! is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with opsu!. If not, see . */ package itdelatrisu.opsu.objects.curves; /** * Representation of a Centripetal Catmull–Rom spline. * (Currently not technically Centripetal Catmull–Rom.) * http://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline * * @author fluddokt (https://github.com/fluddokt) */ public class CentripetalCatmullRom extends CurveType { /** The time values of the Catmull curve. */ private float [] time; /** The control points of the Catmull curve. */ private Vec2f[] points; /** * Constructor. * @param points the control points of the curve */ protected CentripetalCatmullRom(Vec2f[] points) { if (points.length != 4) throw new RuntimeException(String.format("Need exactly 4 points to initialize CentripetalCatmullRom, %d provided.", points.length)); this.points = points; time = new float[4]; time[0] = 0; float approxLength = 0; for (int i = 1; i < 4; i++) { float len = 0; if (i > 0) len = points[i].cpy().sub(points[i - 1]).len(); if (len <= 0) len += 0.0001f; approxLength += len; // time[i] = (float) Math.sqrt(len) + time[i-1];// ^(0.5) time[i] = i; } init(approxLength / 2); } @Override public Vec2f pointAt(float t) { t = t * (time[2] - time[1]) + time[1]; Vec2f A1 = points[0].cpy().scale((time[1] - t) / (time[1] - time[0])) .add(points[1].cpy().scale((t - time[0]) / (time[1] - time[0]))); Vec2f A2 = points[1].cpy().scale((time[2] - t) / (time[2] - time[1])) .add(points[2].cpy().scale((t - time[1]) / (time[2] - time[1]))); Vec2f A3 = points[2].cpy().scale((time[3] - t) / (time[3] - time[2])) .add(points[3].cpy().scale((t - time[2]) / (time[3] - time[2]))); Vec2f B1 = A1.cpy().scale((time[2] - t) / (time[2] - time[0])) .add(A2.cpy().scale((t - time[0]) / (time[2] - time[0]))); Vec2f B2 = A2.cpy().scale((time[3] - t) / (time[3] - time[1])) .add(A3.cpy().scale((t - time[1]) / (time[3] - time[1]))); Vec2f C = B1.cpy().scale((time[2] - t) / (time[2] - time[1])) .add(B2.cpy().scale((t - time[1]) / (time[2] - time[1]))); return C; } }