Java tutorial
/* * jcurl curling simulation framework * Copyright (C) 2005 M. Rohrmoser * * This program 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 2 of the License, or (at your * option) any later version. * * This program 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 this program; if not, write to the Free Software Foundation, Inc., * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package org.jcurl.core.base; import java.awt.geom.AffineTransform; import java.awt.geom.NoninvertibleTransformException; import java.awt.geom.Point2D; import org.apache.commons.logging.Log; import org.jcurl.core.helpers.JCLoggerFactory; /** * Abstract base class for collission models. * * @see org.jcurl.model.CurveFactory * @author <a href="mailto:jcurl@gmx.net">M. Rohrmoser </a> * @version $Id$ */ public abstract class Collider extends Object { private static final float _Rad = RockProps.DEFAULT.getRadius(); private static final float HIT_MAX_DIST = 1e-6F; private static final Log log = JCLoggerFactory.getLogger(Collider.class); /** Maximum distance [m] of two positions to consider them touching */ public static final double MaxDistSq = sqr(_Rad + _Rad + HIT_MAX_DIST); protected static double abs(final double a) { return Math.abs(a); } /** * Compute the trafo to the right handed coordinate-system with origin * <code>orig</code> and positive y-axis pointing from <code>a</code> to * <code>b</code>. * * @param orig * @param a * @param b * @param mat * @return the given matrix */ public static AffineTransform getInverseTrafo(final Point2D orig, final Point2D a, final Point2D b, final AffineTransform mat) { double dx = b.getX() - a.getX(); double dy = b.getY() - a.getY(); final double d = Math.sqrt(dx * dx + dy * dy); dx /= d; dy /= d; mat.setTransform(dy, -dx, dx, dy, 0, 0); mat.translate(-orig.getX(), -orig.getY()); return mat; } public static Collider newInstance(final Class clz) { final Class parent = Collider.class; if (!parent.isAssignableFrom(clz)) throw new IllegalArgumentException( "Class [" + clz.getName() + "] is no descendant of [" + parent.getName() + "]"); try { return (Collider) clz.newInstance(); } catch (InstantiationException e) { final IllegalArgumentException ex = new IllegalArgumentException(); ex.initCause(e); throw ex; } catch (IllegalAccessException e) { final IllegalArgumentException ex = new IllegalArgumentException(); ex.initCause(e); throw ex; } } protected static byte sgn(final double a) { if (a < 0) return -1; if (a > 0) return 1; return 0; } protected static final double sqr(final double a) { return a * a; } protected static double sqrt(final double a) { return Math.sqrt(a); } /** * Iterate over all positions and call * {@link Collider#computeWC(Rock, Rock, Rock, Rock, AffineTransform)} for * each pair. * * @see Collider#computeWC(Rock, Rock, Rock, Rock, AffineTransform) * @param pos * @param speed * @return bitmask of the changed positions */ public int compute(PositionSet pos, SpeedSet speed) { if (log.isDebugEnabled()) log.debug("compute()"); int hits = 0; final AffineTransform mat = new AffineTransform(); for (int B = 0; B < RockSet.ROCKS_PER_SET; B++) { for (int A = 0; A < B; A++) { if (log.isDebugEnabled()) log.debug("Compute hit " + A + "<->" + B); if (computeWC(pos.getRock(A), pos.getRock(B), speed.getRock(A), speed.getRock(B), mat)) { // mark the positions' bits hit hits |= (1 << A); hits |= (1 << B); } } } if (log.isDebugEnabled()) log.debug("hit positions: " + Integer.toBinaryString(hits)); return hits; } /** * Compute a collision in rock-coordinates. * * @param va * speed of rock a * @param vb * speed of rock b (Zero before the hit) */ public abstract void computeRC(final Rock va, final Rock vb); /** * Check distance, speed of approach, transform speeds to rock-coordinates, * call {@link #computeRC(Rock, Rock)}and transform back to wc afterwards. * * @param xa * @param xb * @param va * @param vb * @param mat * may be null. If not avoids frequent instanciations * @return <code>true</code> hit, <code>false</code> no hit. */ public boolean computeWC(final Rock xa, final Rock xb, final Rock va, final Rock vb, AffineTransform mat) { if (mat == null) mat = new AffineTransform(); // check distance if (xa.distanceSq(xb) > MaxDistSq) { if (log.isDebugEnabled()) log.debug("Too far away distance=" + (xa.distance(xb) - (_Rad + _Rad))); return false; } // change the coordinate system to rock-coordinates final Rock _va = (Rock) va.clone(); final Rock _vb = (Rock) vb.clone(); getInverseTrafo(vb, xa, xb, mat); try { // transform mat.inverseTransform(va, _va); mat.inverseTransform(vb, _vb); } catch (NoninvertibleTransformException e) { throw new RuntimeException("Matrix must be invertible", e); } // check speed of approach if (!_va.nonZero()) return false; if (log.isDebugEnabled()) log.debug("hit!"); // physical model computeRC(_va, _vb); // re-transform mat.transform(_va, va); va.setZ(_va.getZ()); mat.transform(_vb, vb); vb.setZ(_vb.getZ()); return true; } }