Source: physics/p2/RevoluteConstraint.js

/**
* @author       Richard Davey <rich@photonstorm.com>
* @copyright    2014 Photon Storm Ltd.
* @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/

/**
* Connects two bodies at given offset points, letting them rotate relative to each other around this point.
* The pivot points are given in world (pixel) coordinates.
*
* @class Phaser.Physics.P2.RevoluteConstraint
* @constructor
* @param {Phaser.Physics.P2} world - A reference to the P2 World.
* @param {p2.Body} bodyA - First connected body.
* @param {Float32Array} pivotA - The point relative to the center of mass of bodyA which bodyA is constrained to. The value is an array with 2 elements matching x and y, i.e: [32, 32].
* @param {p2.Body} bodyB - Second connected body.
* @param {Float32Array} pivotB - The point relative to the center of mass of bodyB which bodyB is constrained to. The value is an array with 2 elements matching x and y, i.e: [32, 32].
* @param {number} [maxForce=0] - The maximum force that should be applied to constrain the bodies.
* @param {Float32Array} [worldPivot=null] - A pivot point given in world coordinates. If specified, localPivotA and localPivotB are automatically computed from this value.
*/
Phaser.Physics.P2.RevoluteConstraint = function (world, bodyA, pivotA, bodyB, pivotB, maxForce, worldPivot) {

    if (typeof maxForce === 'undefined') { maxForce = Number.MAX_VALUE; }
    if (typeof worldPivot === 'undefined') { worldPivot = null; }

    /**
    * @property {Phaser.Game} game - Local reference to game.
    */
    this.game = world.game;

    /**
    * @property {Phaser.Physics.P2} world - Local reference to P2 World.
    */
    this.world = world;

    pivotA = [ world.pxmi(pivotA[0]), world.pxmi(pivotA[1]) ];
    pivotB = [ world.pxmi(pivotB[0]), world.pxmi(pivotB[1]) ];

    if (worldPivot)
    {
        worldPivot = [ world.pxmi(worldPivot[0]), world.pxmi(worldPivot[1]) ];
    }

    var options = { worldPivot: worldPivot, localPivotA: pivotA, localPivotB: pivotB, maxForce: maxForce };

    p2.RevoluteConstraint.call(this, bodyA, bodyB, options);

};

Phaser.Physics.P2.RevoluteConstraint.prototype = Object.create(p2.RevoluteConstraint.prototype);
Phaser.Physics.P2.RevoluteConstraint.prototype.constructor = Phaser.Physics.P2.RevoluteConstraint;