/*******************************************************************************
 * 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,
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 ******************************************************************************/
/**
 * Created at 12:11:41 PM Jan 23, 2011
 */

package org.jbox2d.dynamics.joints;

import org.jbox2d.common.Settings;
import org.jbox2d.common.Vec2;
import org.jbox2d.dynamics.Body;

/** Pulley joint definition. This requires two ground anchors, two dynamic body anchor points, and a pulley ratio.
 * 
 * @author Daniel Murphy */
public class PulleyJointDef extends JointDef {

	/** The first ground anchor in world coordinates. This point never moves. */
	public Vec2 groundAnchorA;

	/** The second ground anchor in world coordinates. This point never moves. */
	public Vec2 groundAnchorB;

	/** The local anchor point relative to bodyA's origin. */
	public Vec2 localAnchorA;

	/** The local anchor point relative to bodyB's origin. */
	public Vec2 localAnchorB;

	/** The a reference length for the segment attached to bodyA. */
	public float lengthA;

	/** The a reference length for the segment attached to bodyB. */
	public float lengthB;

	/** The pulley ratio, used to simulate a block-and-tackle. */
	public float ratio;

	public PulleyJointDef () {
		super(JointType.PULLEY);
		groundAnchorA = new Vec2(-1.0f, 1.0f);
		groundAnchorB = new Vec2(1.0f, 1.0f);
		localAnchorA = new Vec2(-1.0f, 0.0f);
		localAnchorB = new Vec2(1.0f, 0.0f);
		lengthA = 0.0f;
		lengthB = 0.0f;
		ratio = 1.0f;
		collideConnected = true;
	}

	/** Initialize the bodies, anchors, lengths, max lengths, and ratio using the world anchors. */
	public void initialize (Body b1, Body b2, Vec2 ga1, Vec2 ga2, Vec2 anchor1, Vec2 anchor2, float r) {
		bodyA = b1;
		bodyB = b2;
		groundAnchorA = ga1;
		groundAnchorB = ga2;
		localAnchorA = bodyA.getLocalPoint(anchor1);
		localAnchorB = bodyB.getLocalPoint(anchor2);
		Vec2 d1 = anchor1.sub(ga1);
		lengthA = d1.length();
		Vec2 d2 = anchor2.sub(ga2);
		lengthB = d2.length();
		ratio = r;
		assert (ratio > Settings.EPSILON);
	}
}
