Package org.jbox2d.dynamics

Source Code of org.jbox2d.dynamics.ContactManager

/*******************************************************************************
* 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.
*     * Neither the name of the <organization> nor the
*       names of its contributors may be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* 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 DANIEL MURPHY 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.
******************************************************************************/
package org.jbox2d.dynamics;

import org.jbox2d.callbacks.ContactFilter;
import org.jbox2d.callbacks.ContactListener;
import org.jbox2d.callbacks.PairCallback;
import org.jbox2d.collision.broadphase.BroadPhase;
import org.jbox2d.collision.broadphase.DynamicTreeNode;
import org.jbox2d.dynamics.contacts.Contact;
import org.jbox2d.dynamics.contacts.ContactEdge;

// updated to rev 100
/**
* Delegate of World.
*
* @author Daniel Murphy
*/
public class ContactManager implements PairCallback {
 
  public BroadPhase m_broadPhase;
  public Contact m_contactList;
  public int m_contactCount;
  public ContactFilter m_contactFilter;
  public ContactListener m_contactListener;
 
  private final World pool;
 
  public ContactManager(World argPool) {
    m_contactList = null;
    m_contactCount = 0;
    m_contactFilter = new ContactFilter();
    m_contactListener = null;
    m_broadPhase = new BroadPhase();
    pool = argPool;
  }
 
  /**
   * Broad-phase callback.
   *
   * @param proxyUserDataA
   * @param proxyUserDataB
   */
  public void addPair(Object proxyUserDataA, Object proxyUserDataB) {
    Fixture fixtureA = (Fixture) proxyUserDataA;
    Fixture fixtureB = (Fixture) proxyUserDataB;
   
    Body bodyA = fixtureA.getBody();
    Body bodyB = fixtureB.getBody();
   
    // Are the fixtures on the same body?
    if (bodyA == bodyB) {
      return;
    }
   
    // Does a contact already exist?
    ContactEdge edge = bodyB.getContactList();
    while (edge != null) {
      if (edge.other == bodyA) {
        Fixture fA = edge.contact.getFixtureA();
        Fixture fB = edge.contact.getFixtureB();
        if (fA == fixtureA && fB == fixtureB) {
          // A contact already exists.
          return;
        }
       
        if (fA == fixtureB && fB == fixtureA) {
          // A contact already exists.
          return;
        }
      }
     
      edge = edge.next;
    }
   
    // Does a joint override collision? is at least one body dynamic?
    if (bodyB.shouldCollide(bodyA) == false) {
      return;
    }
   
    // Check user filtering.
    if (m_contactFilter != null && m_contactFilter.shouldCollide(fixtureA, fixtureB) == false) {
      return;
    }
   
    // Call the factory.
    Contact c = pool.popContact(fixtureA, fixtureB);
   
    // Contact creation may swap fixtures.
    fixtureA = c.getFixtureA();
    fixtureB = c.getFixtureB();
    bodyA = fixtureA.getBody();
    bodyB = fixtureB.getBody();
   
    // Insert into the world.
    c.m_prev = null;
    c.m_next = m_contactList;
    if (m_contactList != null) {
      m_contactList.m_prev = c;
    }
    m_contactList = c;
   
    // Connect to island graph.
   
    // Connect to body A
    c.m_nodeA.contact = c;
    c.m_nodeA.other = bodyB;
   
    c.m_nodeA.prev = null;
    c.m_nodeA.next = bodyA.m_contactList;
    if (bodyA.m_contactList != null) {
      bodyA.m_contactList.prev = c.m_nodeA;
    }
    bodyA.m_contactList = c.m_nodeA;
   
    // Connect to body B
    c.m_nodeB.contact = c;
    c.m_nodeB.other = bodyA;
   
    c.m_nodeB.prev = null;
    c.m_nodeB.next = bodyB.m_contactList;
    if (bodyB.m_contactList != null) {
      bodyB.m_contactList.prev = c.m_nodeB;
    }
    bodyB.m_contactList = c.m_nodeB;
   
    ++m_contactCount;
  }
 
  public void findNewContacts() {
    m_broadPhase.updatePairs(this);
  }
 
  public void destroy(Contact c) {
    Fixture fixtureA = c.getFixtureA();
    Fixture fixtureB = c.getFixtureB();
    Body bodyA = fixtureA.getBody();
    Body bodyB = fixtureB.getBody();
   
    if (m_contactListener != null && c.isTouching()) {
      m_contactListener.endContact(c);
    }
   
    // Remove from the world.
    if (c.m_prev != null) {
      c.m_prev.m_next = c.m_next;
    }
   
    if (c.m_next != null) {
      c.m_next.m_prev = c.m_prev;
    }
   
    if (c == m_contactList) {
      m_contactList = c.m_next;
    }
   
    // Remove from body 1
    if (c.m_nodeA.prev != null) {
      c.m_nodeA.prev.next = c.m_nodeA.next;
    }
   
    if (c.m_nodeA.next != null) {
      c.m_nodeA.next.prev = c.m_nodeA.prev;
    }
   
    if (c.m_nodeA == bodyA.m_contactList) {
      bodyA.m_contactList = c.m_nodeA.next;
    }
   
    // Remove from body 2
    if (c.m_nodeB.prev != null) {
      c.m_nodeB.prev.next = c.m_nodeB.next;
    }
   
    if (c.m_nodeB.next != null) {
      c.m_nodeB.next.prev = c.m_nodeB.prev;
    }
   
    if (c.m_nodeB == bodyB.m_contactList) {
      bodyB.m_contactList = c.m_nodeB.next;
    }
   
    // Call the factory.
    pool.pushContact(c);
    --m_contactCount;
  }
 
  /**
   * This is the top level collision call for the time step. Here
   * all the narrow phase collision is processed for the world
   * contact list.
   */
  public void collide() {
    // Update awake contacts.
    Contact c = m_contactList;
    while (c != null) {
      Fixture fixtureA = c.getFixtureA();
      Fixture fixtureB = c.getFixtureB();
      Body bodyA = fixtureA.getBody();
      Body bodyB = fixtureB.getBody();
     
      if (bodyA.isAwake() == false && bodyB.isAwake() == false) {
        c = c.getNext();
        continue;
      }
     
      // is this contact flagged for filtering?
      if ((c.m_flags & Contact.FILTER_FLAG) == Contact.FILTER_FLAG) {
        // Should these bodies collide?
        if (bodyB.shouldCollide(bodyA) == false) {
          Contact cNuke = c;
          c = cNuke.getNext();
          destroy(cNuke);
          continue;
        }
       
        // Check user filtering.
        if (m_contactFilter != null && m_contactFilter.shouldCollide(fixtureA, fixtureB) == false) {
          Contact cNuke = c;
          c = cNuke.getNext();
          destroy(cNuke);
          continue;
        }
       
        // Clear the filtering flag.
        c.m_flags &= ~Contact.FILTER_FLAG;
      }
     
      DynamicTreeNode proxyIdA = fixtureA.m_proxy;
      DynamicTreeNode proxyIdB = fixtureB.m_proxy;
      boolean overlap = m_broadPhase.testOverlap(proxyIdA, proxyIdB);
     
      // Here we destroy contacts that cease to overlap in the broad-phase.
      if (overlap == false) {
        Contact cNuke = c;
        c = cNuke.getNext();
        destroy(cNuke);
        continue;
      }
     
      // The contact persists.
      c.update(m_contactListener);
      c = c.getNext();
    }
  }
}
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