MouseJoint.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.joints;

import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.Joint;
import com.badlogic.gdx.physics.box2d.World;

/**
 * A mouse joint is used to make a point on a body track a specified world point. This a soft constraint with a maximum
 * force. This allows the constraint to stretch and without applying huge forces. NOTE: this joint is not documented in
 * the manual because it was developed to be used in the testbed. If you want to learn how to use the mouse joint, look
 * at the testbed.
 */
public class MouseJoint extends Joint {
	// @off
	/*JNI
	#include <Box2D/Box2D.h>
	 */

	public MouseJoint(World world, long addr) {
		super(world, addr);
	}

	/** Use this to update the target point. */
	public void setTarget(Vector2 target) {
		jniSetTarget(addr, target.x, target.y);
	}

	private native void jniSetTarget(long addr, float x, float y); /*
																	b2MouseJoint* joint = (b2MouseJoint*)addr;
																	joint->SetTarget( b2Vec2(x, y ) );
																	*/

	/** Use this to update the target point. */
	final float[] tmp = new float[2];
	private final Vector2 target = new Vector2();

	public Vector2 getTarget() {
		jniGetTarget(addr, tmp);
		target.x = tmp[0];
		target.y = tmp[1];
		return target;
	}

	private native void jniGetTarget(long addr, float[] target); /*
																	b2MouseJoint* joint = (b2MouseJoint*)addr;
																	target[0] = joint->GetTarget().x;
																	target[1] = joint->GetTarget().y;
																	*/

	/** Set/get the maximum force in Newtons. */
	public void setMaxForce(float force) {
		jniSetMaxForce(addr, force);
	}

	private native void jniSetMaxForce(long addr, float force); /*
																b2MouseJoint* joint = (b2MouseJoint*)addr;
																joint->SetMaxForce( force );
																*/

	/** Set/get the maximum force in Newtons. */
	public float getMaxForce() {
		return jniGetMaxForce(addr);
	}

	private native float jniGetMaxForce(long addr); /*
													b2MouseJoint* joint = (b2MouseJoint*)addr;
													return joint->GetMaxForce();
													*/

	/** Set/get the frequency in Hertz. */
	public void setFrequency(float hz) {
		jniSetFrequency(addr, hz);
	}

	private native void jniSetFrequency(long addr, float hz); /*
																b2MouseJoint* joint = (b2MouseJoint*)addr;
																joint->SetFrequency(hz);
																*/

	/** Set/get the frequency in Hertz. */
	public float getFrequency() {
		return jniGetFrequency(addr);
	}

	private native float jniGetFrequency(long addr); /*
														b2MouseJoint* joint = (b2MouseJoint*)addr;
														return joint->GetFrequency();
														*/

	/** Set/get the damping ratio (dimensionless). */
	public void setDampingRatio(float ratio) {
		jniSetDampingRatio(addr, ratio);
	}

	private native void jniSetDampingRatio(long addr, float ratio); /*
																	b2MouseJoint* joint = (b2MouseJoint*)addr;
																	joint->SetDampingRatio( ratio );
																	*/

	/** Set/get the damping ratio (dimensionless). */
	public float getDampingRatio() {
		return jniGetDampingRatio(addr);
	}

	private native float jniGetDampingRatio(long addr); /*
														b2MouseJoint* joint = (b2MouseJoint*)addr;
														return joint->GetDampingRatio();
														*/
}