ConveyorBelt.java

/*******************************************************************************
 * 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.
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 * 	  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,
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 * 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,
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package org.jbox2d.testbed.tests;

import org.jbox2d.collision.Manifold;
import org.jbox2d.collision.shapes.EdgeShape;
import org.jbox2d.collision.shapes.PolygonShape;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.Body;
import org.jbox2d.dynamics.BodyDef;
import org.jbox2d.dynamics.BodyType;
import org.jbox2d.dynamics.Fixture;
import org.jbox2d.dynamics.FixtureDef;
import org.jbox2d.dynamics.contacts.Contact;
import org.jbox2d.testbed.framework.TestbedTest;

public class ConveyorBelt extends TestbedTest {
  private static long platformTag = 98752L;
  private Fixture m_platform;
  
  @Override
  public Long getTag(Fixture argFixture) {
    if (argFixture == m_platform) {
      return platformTag;
    }
    return super.getTag(argFixture);
  }
  
  @Override
  public void processFixture(Fixture argFixture, Long argTag) {
    if(argTag == platformTag) {
      m_platform = argFixture;
      return;
    }
    super.processFixture(argFixture, argTag);
  }

  @Override
  public boolean isSaveLoadEnabled() {
    return true;
  }
  
  @Override
  public void initTest(boolean deserialized) {
    if(deserialized) {
      return;
    }
    // Ground
    {

      EdgeShape shape = new EdgeShape();
      shape.set(new Vec2(-20.0f, 0.0f), new Vec2(20.0f, 0.0f));
      getGroundBody().createFixture(shape, 0.0f);
    }

    // Platform
    {
      BodyDef bd = new BodyDef();
      bd.position.set(-5.0f, 5.0f);
      Body body = getWorld().createBody(bd);

      PolygonShape shape = new PolygonShape();
      shape.setAsBox(10.0f, 0.5f);

      FixtureDef fd = new FixtureDef();
      fd.shape = shape;
      fd.friction = 0.8f;
      m_platform = body.createFixture(fd);
    }

    // Boxes
    for (int i = 0; i < 5; ++i) {
      BodyDef bd = new BodyDef();
      bd.type = BodyType.DYNAMIC;
      bd.position.set(-10.0f + 2.0f * i, 7.0f);
      Body body = m_world.createBody(bd);

      PolygonShape shape = new PolygonShape();
      shape.setAsBox(0.5f, 0.5f);
      body.createFixture(shape, 20.0f);
    }
  }

  @Override
  public void preSolve(Contact contact, Manifold oldManifold) {
    super.preSolve(contact, oldManifold);

    Fixture fixtureA = contact.getFixtureA();
    Fixture fixtureB = contact.getFixtureB();

    if (fixtureA == m_platform || fixtureB == m_platform) {
      contact.setTangentSpeed(5.0f);
    }
  }

  @Override
  public String getTestName() {
    return "Conveyor Belt";
  }
}