content: /*
   * FXGL - JavaFX Game Library. The MIT License (MIT).
   * Copyright (c) AlmasB (almaslvl@gmail.com).
   * See LICENSE for details.
   */
  /*
   * JBox2D - A Java Port of Erin Catto's Box2D
   *
   * JBox2D homepage: http://jbox2d.sourceforge.net/
   * Box2D homepage: http://www.box2d.org
   *
   * This software is provided 'as-is', without any express or implied
   * warranty.  In no event will the authors be held liable for any damages
   * arising from the use of this software.
   *
   * Permission is granted to anyone to use this software for any purpose,
   * including commercial applications, and to alter it and redistribute it
   * freely, subject to the following restrictions:
   *
   * 1. The origin of this software must not be misrepresented; you must not
   * claim that you wrote the original software. If you use this software
   * in a product, an acknowledgment in the product documentation would be
   * appreciated but is not required.
   * 2. Altered source versions must be plainly marked as such, and must not be
   * misrepresented as being the original software.
   * 3. This notice may not be removed or altered from any source distribution.
   */
  
  package com.almasb.fxgl.physics.box2d.dynamics.joints;
  
  import com.almasb.fxgl.core.math.Vec2;
  import com.almasb.fxgl.physics.box2d.dynamics.Body;
  import com.almasb.fxgl.physics.box2d.dynamics.World;
  
  /**
   * Distance joint definition.
   * This requires defining an anchor point on both bodies and the non-zero length of the distance joint.
   * The definition uses local anchor points so that the initial configuration can violate the constraint slightly.
   * This helps when saving and loading a game.
   * Do not use a zero or short length.
   */
  public class DistanceJointDef extends JointDef<DistanceJoint> {
  
      /**
       * The local anchor point relative to body1's origin.
       */
      public final Vec2 localAnchorA = new Vec2();
  
      /**
       * The local anchor point relative to body2's origin.
       */
      public final Vec2 localAnchorB = new Vec2();
  
      /**
       * The equilibrium length between the anchor points.
       */
      public float length = 1.0f;
  
      /**
       * The mass-spring-damper frequency in Hertz.
       */
      public float frequencyHz = 0.0f;
  
      /**
       * The damping ratio.
       * 0 = no damping, 1 = critical damping.
       */
      public float dampingRatio = 0.0f;
  
      /**
       * Initialize the bodies, anchors, and length using the world anchors.
       *
       * @param anchor1 World anchor on first body
       * @param anchor2 World anchor on second body
       */
      public void initialize(Body b1, Body b2, Vec2 anchor1, Vec2 anchor2) {
          setBodyA(b1);
          setBodyB(b2);
          localAnchorA.set(b1.getLocalPoint(anchor1));
          localAnchorB.set(b2.getLocalPoint(anchor2));
          Vec2 d = anchor2.sub(anchor1);
          length = d.length();
      }
  
      @Override
      protected DistanceJoint createJoint(World world) {
          return new DistanceJoint(world.getPool(), this);
      }
  }
  