Android Open Source - gameengine Revolute Joint Def

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Java Source Code

/*******************************************************************************
 * Copyright 2011 See AUTHORS file.//from   w  ww. j a v a 2 s.  c om
 * 
 * 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;

/**
 * Revolute joint definition. This requires defining an anchor point where the
 * bodies are joined. The definition uses local anchor points so that the
 * initial configuration can violate the constraint slightly. You also need to
 * specify the initial relative angle for joint limits. This helps when saving
 * and loading a game. The local anchor points are measured from the body's
 * origin rather than the center of mass because: 1. you might not know where
 * the center of mass will be. 2. if you add/remove shapes from a body and
 * recompute the mass, the joints will be broken.
 */
public class RevoluteJointDef extends JointDef {
    public RevoluteJointDef() {
        type = JointType.RevoluteJoint;
    }

    /**
     * Initialize the bodies, anchors, and reference angle using a world anchor
     * point.
     */
    public void initialize(Body bodyA, Body bodyB, Vector2 anchor) {
        this.bodyA = bodyA;
        this.bodyB = bodyB;
        localAnchorA.set(bodyA.getLocalPoint(anchor));
        localAnchorB.set(bodyB.getLocalPoint(anchor));
        referenceAngle = bodyB.getAngle() - bodyA.getAngle();
    }

    /** The local anchor point relative to body1's origin. */
    public final Vector2 localAnchorA = new Vector2();

    /** The local anchor point relative to body2's origin. */
    public final Vector2 localAnchorB = new Vector2();;

    /** The body2 angle minus body1 angle in the reference state (radians). */
    public float referenceAngle = 0;

    /** A flag to enable joint limits. */
    public boolean enableLimit = false;

    /** The lower angle for the joint limit (radians). */
    public float lowerAngle = 0;

    /** The upper angle for the joint limit (radians). */
    public float upperAngle = 0;

    /** A flag to enable the joint motor. */
    public boolean enableMotor = false;

    /** The desired motor speed. Usually in radians per second. */
    public float motorSpeed = 0;

    /**
     * The maximum motor torque used to achieve the desired motor speed. Usually
     * in N-m.
     */
    public float maxMotorTorque = 0;
}

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