content: /*
   * FXGL - JavaFX Game Library. The MIT License (MIT).
   * Copyright (c) AlmasB (almaslvl@gmail.com).
   * See LICENSE for details.
   */
  
  /*
   * Copyright (c) 2013, 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.
   */
  
  package com.almasb.fxgl.physics.box2d.callbacks;
  
  import com.almasb.fxgl.physics.box2d.collision.Manifold;
  import com.almasb.fxgl.physics.box2d.dynamics.contacts.Contact;
  
  /**
   * Implement this class to get contact information. You can use these results for
   * things like sounds and game logic. You can also get contact results by
   * traversing the contact lists after the time step. However, you might miss
   * some contacts because continuous physics leads to sub-stepping.
   * Additionally you may receive multiple callbacks for the same contact in a
   * single time step.
   * You should strive to make your callbacks efficient because there may be
   * many callbacks per time step.
   *
   * @warning You cannot create/destroy Box2D entities inside these callbacks.
   * @author Daniel Murphy
   */
  public interface ContactListener {
  
      /**
       * Called when two fixtures begin to touch.
       *
       * @param contact contact info
       */
      void beginContact(Contact contact);
  
      /**
       * Called when two fixtures cease to touch.
       *
       * @param contact contact info
       */
      void endContact(Contact contact);
  
      /**
       * This is called after a contact is updated. This allows you to inspect a
       * contact before it goes to the solver. If you are careful, you can modify the
       * contact manifold (e.g. disable contact).
       * A copy of the old manifold is provided so that you can detect changes.
       * <p>
       * Note:
       * <ul>
       *     <li>This is called only for awake bodies.</li>
       *     <li>This is called even when the number of contact points is zero.</li>
       *     <li>This is not called for sensors.</li>
       *     <li>If you set the number of contact points to zero, you will not
       * get an EndContact callback. However, you may get a BeginContact callback the next step.</li>
       *     <li>The oldManifold parameter is pooled, so it will be the same object for every callback
       * for each thread.</li>
       * </ul>
       *
       * @param contact contact info
       * @param oldManifold the old manifold
       */
      void preSolve(Contact contact, Manifold oldManifold);
  
      /**
       * This lets you inspect a contact after the solver is finished. This is useful
       * for inspecting impulses.
       * <p>
       *     Note:
       *     <ul>
       *         <li>The contact manifold does not include time of impact impulses, which can be
       * arbitrarily large if the sub-step is small. Hence the impulse is provided explicitly
       * in a separate data structure.</li>
       *         <li>This is only called for contacts that are touching, solid, and awake.</li>
       *         <li>The impulse parameter is usually a pooled variable, so it will be modified after
       * this call.</li>
       *     </ul>
       * </p>
       *
       * @param contact contact info
       * @param impulse contact impulse
       */
      void postSolve(Contact contact, ContactImpulse impulse);
  }
  