Joint.java

/*******************************************************************************
 * 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;

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

public abstract class Joint {
	// @off
	/*JNI
#include <Box2D/Box2D.h> 
	 */
	/** the address of the joint **/
	protected long addr;

	/** world **/
	private final World world;

	/** temporary float array **/
	private final float[] tmp = new float[2];

	/** user data **/
	private Object userData;

	/** joint edge a **/
	protected JointEdge jointEdgeA;

	/** joint edge b **/
	protected JointEdge jointEdgeB;

	/** Constructs a new joint
	 * @param addr the address of the joint */
	protected Joint (World world, long addr) {
		this.world = world;
		this.addr = addr;
	}

	/** Get the type of the concrete joint. */
	public JointType getType () {
		int type = jniGetType(addr);
		if (type > 0 && type < JointType.valueTypes.length)
			return JointType.valueTypes[type];
		else
			return JointType.Unknown;
	}

	private native int jniGetType (long addr); /*
		b2Joint* joint = (b2Joint*)addr;
		return joint->GetType();
	*/

	/** Get the first body attached to this joint. */
	public Body getBodyA () {
		return world.bodies.get(jniGetBodyA(addr));
	}

	private native long jniGetBodyA (long addr); /*
		b2Joint* joint = (b2Joint*)addr;
		return (jlong)joint->GetBodyA();
	*/

	/** Get the second body attached to this joint. */
	public Body getBodyB () {
		return world.bodies.get(jniGetBodyB(addr));
	}

	private native long jniGetBodyB (long addr); /*
		b2Joint* joint = (b2Joint*)addr;
		return (jlong)joint->GetBodyB();
	*/

	/** Get the anchor point on bodyA in world coordinates. */
	private final Vector2 anchorA = new Vector2();

	public Vector2 getAnchorA () {
		jniGetAnchorA(addr, tmp);
		anchorA.x = tmp[0];
		anchorA.y = tmp[1];
		return anchorA;
	}

	private native void jniGetAnchorA (long addr, float[] anchorA); /*
		b2Joint* joint = (b2Joint*)addr;
		b2Vec2 a = joint->GetAnchorA();
		anchorA[0] = a.x;
		anchorA[1] = a.y;
	*/

	/** Get the anchor point on bodyB in world coordinates. */
	private final Vector2 anchorB = new Vector2();

	public Vector2 getAnchorB () {
		jniGetAnchorB(addr, tmp);
		anchorB.x = tmp[0];
		anchorB.y = tmp[1];
		return anchorB;
	}

	private native void jniGetAnchorB (long addr, float[] anchorB); /*
		b2Joint* joint = (b2Joint*)addr;
		b2Vec2 a = joint->GetAnchorB();
		anchorB[0] = a.x;
		anchorB[1] = a.y;
	*/

	public boolean getCollideConnected() {
		return jniGetCollideConnected(addr);
	}

	private native boolean jniGetCollideConnected(long addr); /*
		b2Joint* joint = (b2Joint*) addr;
		return joint->GetCollideConnected();
	*/

	/** Get the reaction force on body2 at the joint anchor in Newtons. */
	private final Vector2 reactionForce = new Vector2();

	public Vector2 getReactionForce (float inv_dt) {
		jniGetReactionForce(addr, inv_dt, tmp);
		reactionForce.x = tmp[0];
		reactionForce.y = tmp[1];
		return reactionForce;
	}

	private native void jniGetReactionForce (long addr, float inv_dt, float[] reactionForce); /*
		b2Joint* joint = (b2Joint*)addr;
		b2Vec2 f = joint->GetReactionForce(inv_dt);
		reactionForce[0] = f.x;
		reactionForce[1] = f.y;
	*/

	/** Get the reaction torque on body2 in N*m. */
	public float getReactionTorque (float inv_dt) {
		return jniGetReactionTorque(addr, inv_dt);
	}

	private native float jniGetReactionTorque (long addr, float inv_dt); /*
		b2Joint* joint = (b2Joint*)addr;
		return joint->GetReactionTorque(inv_dt);
	*/

// /// Get the next joint the world joint list.
// b2Joint* GetNext();
//

	/** Get the user data */
	public Object getUserData () {
		return userData;
	}

	/** Set the user data */
	public void setUserData (Object userData) {
		this.userData = userData;
	}

	/** Short-cut function to determine if either body is inactive. */
	public boolean isActive () {
		return jniIsActive(addr);
	}

	private native boolean jniIsActive (long addr); /*
		b2Joint* joint = (b2Joint*)addr;
		return joint->IsActive();
	*/
	

}