1 /******************************************************************************* 2 * Copyright (c) 2013, Daniel Murphy 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without modification, 6 * are permitted provided that the following conditions are met: 7 * * Redistributions of source code must retain the above copyright notice, 8 * this list of conditions and the following disclaimer. 9 * * Redistributions in binary form must reproduce the above copyright notice, 10 * this list of conditions and the following disclaimer in the documentation 11 * and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 17 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 19 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 20 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 21 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 22 * POSSIBILITY OF SUCH DAMAGE. 23 ******************************************************************************/ 24 /* 25 * JBox2D - A Java Port of Erin Catto's Box2D 26 * 27 * JBox2D homepage: http://jbox2d.sourceforge.net/ 28 * Box2D homepage: http://www.box2d.org 29 * 30 * This software is provided 'as-is', without any express or implied 31 * warranty. In no event will the authors be held liable for any damages 32 * arising from the use of this software. 33 * 34 * Permission is granted to anyone to use this software for any purpose, 35 * including commercial applications, and to alter it and redistribute it 36 * freely, subject to the following restrictions: 37 * 38 * 1. The origin of this software must not be misrepresented; you must not 39 * claim that you wrote the original software. If you use this software 40 * in a product, an acknowledgment in the product documentation would be 41 * appreciated but is not required. 42 * 2. Altered source versions must be plainly marked as such, and must not be 43 * misrepresented as being the original software. 44 * 3. This notice may not be removed or altered from any source distribution. 45 */ 46 47 package org.jbox2d.dynamics.joints; 48 49 import org.jbox2d.common.Vec2; 50 import org.jbox2d.dynamics.Body; 51 52 //Updated to rev 56->130->142 of b2DistanceJoint.cpp/.h 53 54 /** 55 * Distance joint definition. This requires defining an anchor point on both bodies and the non-zero 56 * length of the distance joint. The definition uses local anchor points so that the initial 57 * configuration can violate the constraint slightly. This helps when saving and loading a game. 58 * 59 * @warning Do not use a zero or short length. 60 */ 61 public class DistanceJointDef extends JointDef { 62 /** The local anchor point relative to body1's origin. */ 63 public final Vec2 localAnchorA; 64 65 /** The local anchor point relative to body2's origin. */ 66 public final Vec2 localAnchorB; 67 68 /** The equilibrium length between the anchor points. */ 69 public float length; 70 71 /** 72 * The mass-spring-damper frequency in Hertz. 73 */ 74 public float frequencyHz; 75 76 /** 77 * The damping ratio. 0 = no damping, 1 = critical damping. 78 */ 79 public float dampingRatio; 80 81 public DistanceJointDef() { 82 super(JointType.DISTANCE); 83 localAnchorA = new Vec2(0.0f, 0.0f); 84 localAnchorB = new Vec2(0.0f, 0.0f); 85 length = 1.0f; 86 frequencyHz = 0.0f; 87 dampingRatio = 0.0f; 88 } 89 90 /** 91 * Initialize the bodies, anchors, and length using the world anchors. 92 * 93 * @param b1 First body 94 * @param b2 Second body 95 * @param anchor1 World anchor on first body 96 * @param anchor2 World anchor on second body 97 */ 98 public void initialize(final Body b1, final Body b2, final Vec2 anchor1, final Vec2 anchor2) { 99 bodyA = b1; 100 bodyB = b2; 101 localAnchorA.set(bodyA.getLocalPoint(anchor1)); 102 localAnchorB.set(bodyB.getLocalPoint(anchor2)); 103 Vec2 d = anchor2.sub(anchor1); 104 length = d.length(); 105 } 106 } 107
