/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.physics.box2d.joints;

import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.Body;
import com.badlogic.gdx.physics.box2d.JointDef;

/** Pulley joint definition. This requires two ground anchors, two dynamic body anchor points, max lengths for each side, and a
 * pulley ratio. */
public class PulleyJointDef extends JointDef {
	private final static float minPulleyLength = 2.0f;

	public PulleyJointDef () {
		type = JointType.PulleyJoint;
		collideConnected = true;
	}

	/** Initialize the bodies, anchors, lengths, max lengths, and ratio using the world anchors. */
	public void initialize (Body bodyA, Body bodyB, Vector2 groundAnchorA, Vector2 groundAnchorB, Vector2 anchorA,
		Vector2 anchorB, float ratio) {
		this.bodyA = bodyA;
		this.bodyB = bodyB;
		this.groundAnchorA.set(groundAnchorA);
		this.groundAnchorB.set(groundAnchorB);
		this.localAnchorA.set(bodyA.getLocalPoint(anchorA));
		this.localAnchorB.set(bodyB.getLocalPoint(anchorB));
		lengthA = anchorA.dst(groundAnchorA);
		lengthB = anchorB.dst(groundAnchorB);
		this.ratio = ratio;
		float C = lengthA + ratio * lengthB;
	}

	/** The first ground anchor in world coordinates. This point never moves. */
	public final Vector2 groundAnchorA = new Vector2(-1, 1);

	/** The second ground anchor in world coordinates. This point never moves. */
	public final Vector2 groundAnchorB = new Vector2(1, 1);

	/** The local anchor point relative to bodyA's origin. */
	public final Vector2 localAnchorA = new Vector2(-1, 0);

	/** The local anchor point relative to bodyB's origin. */
	public final Vector2 localAnchorB = new Vector2(1, 0);

	/** The a reference length for the segment attached to bodyA. */
	public float lengthA = 0;

	/** The a reference length for the segment attached to bodyB. */
	public float lengthB = 0;

	/** The pulley ratio, used to simulate a block-and-tackle. */
	public float ratio = 1;

	@Override
	public org.jbox2d.dynamics.joints.JointDef toJBox2d () {
		org.jbox2d.dynamics.joints.PulleyJointDef jd = new org.jbox2d.dynamics.joints.PulleyJointDef();
		jd.bodyA = bodyA.body;
		jd.bodyB = bodyB.body;
		jd.collideConnected = collideConnected;
		jd.groundAnchorA.set(groundAnchorA.x, groundAnchorB.y);
		jd.groundAnchorB.set(groundAnchorB.x, groundAnchorB.y);
		jd.lengthA = lengthA;
		jd.lengthB = lengthB;
		jd.localAnchorA.set(localAnchorA.x, localAnchorA.y);
		jd.localAnchorB.set(localAnchorB.x, localAnchorB.y);
		jd.ratio = ratio;
		jd.type = org.jbox2d.dynamics.joints.JointType.PULLEY;
		return jd;
	}
}