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A 2D java physics engine, a port of the C++ Box2d engine. This is the core physics engine.
/*******************************************************************************
* Copyright (c) 2011, Daniel Murphy
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
******************************************************************************/
/*
* JBox2D - A Java Port of Erin Catto's Box2D
*
* JBox2D homepage: http://jbox2d.sourceforge.net/
* Box2D homepage: http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
package org.jbox2d.collision;
//FIXME: In the C++ version, this class is a union of
//the key and the features, meaning not that it contains
//both separately, but that the same data can be accessed
//as either. The key there is 32 bit, and each member of
//features is 8 bits.
//
//We need to figure out if this is a problem or not, because
//I have a feeling that as of right now, key is never being
//set anyways. Initial examination seems to show that key is
//always zero. [hacked around for the moment]
//
//Also, it might be better performance-wise to pull features
//to a top level class if inner classes have more overhead (check this).
// updated to rev 100
/** Contact ids to facilitate warm starting.*/
public class ContactID {
/** The features that intersect to form the contact point */
public final Features features;
/** The features that intersect to form the contact point */
public static class Features {
/** The edge that defines the outward contact normal. */
public int referenceEdge;
/** The edge most anti-parallel to the reference edge. */
public int incidentEdge;
/** The vertex (0 or 1) on the incident edge that was clipped. */
public int incidentVertex;
/** A value of 1 indicates that the reference edge is on shape2. */
public int flip;
public Features() {
referenceEdge = incidentEdge = incidentVertex = flip = 0;
}
private Features(final Features f) {
referenceEdge = f.referenceEdge;
incidentEdge = f.incidentEdge;
incidentVertex = f.incidentVertex;
flip = f.flip;
}
private void set(final Features f){
referenceEdge = f.referenceEdge;
incidentEdge = f.incidentEdge;
incidentVertex = f.incidentVertex;
flip = f.flip;
}
private boolean isEqual(final Features f){
return (referenceEdge==f.referenceEdge &&
incidentEdge==f.incidentEdge &&
incidentVertex==f.incidentVertex &&
flip==f.flip);
}
@Override
public String toString() {
final String s = "Features: (" + this.flip + " ," + this.incidentEdge + " ," + this.incidentVertex + " ," + this.referenceEdge + ")";
return s;
}
}
public boolean isEqual(final ContactID cid) {
return cid.features.isEqual(this.features);
}
public ContactID() {
features = new Features();
}
public ContactID(final ContactID c) {
features = new Features(c.features);
}
public void set(final ContactID c){
features.set(c.features);
}
/**
* zeros out the data
*/
public void zero() {
features.flip = 0;
features.incidentEdge = 0;
features.incidentVertex = 0;
features.referenceEdge = 0;
}
}