API Docs for: 0.6.0
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File: src/constraints/PointToPointConstraint.js

module.exports = PointToPointConstraint;

var Constraint = require('./Constraint');
var ContactEquation = require('../equations/ContactEquation');

/**
 * Connects two bodies at given offset points.
 * @class PointToPointConstraint
 * @extends Constraint
 * @constructor
 * @param {Body} bodyA
 * @param {Vec3} pivotA The point relative to the center of mass of bodyA which bodyA is constrained to.
 * @param {Body} bodyB Body that will be constrained in a similar way to the same point as bodyA. We will therefore get sort of a link between bodyA and bodyB. If not specified, bodyA will be constrained to a static point.
 * @param {Vec3} pivotB See pivotA.
 * @param {Number} maxForce The maximum force that should be applied to constrain the bodies.
 *
 * @example
 *     var bodyA = new Body({ mass: 1 });
 *     var bodyB = new Body({ mass: 1 });
 *     bodyA.position.set(-1, 0, 0);
 *     bodyB.position.set(1, 0, 0);
 *     bodyA.addShape(shapeA);
 *     bodyB.addShape(shapeB);
 *     world.addBody(bodyA);
 *     world.addBody(bodyB);
 *     var localPivotA = new Vec3(1, 0, 0);
 *     var localPivotB = new Vec3(-1, 0, 0);
 *     var constraint = new PointToPointConstraint(bodyA, localPivotA, bodyB, localPivotB);
 *     world.addConstraint(constraint);
 */
function PointToPointConstraint(bodyA,pivotA,bodyB,pivotB,maxForce){
    Constraint.call(this,bodyA,bodyB);

    // Equations to be fed to the solver
    var eqs = this.equations = [
        new ContactEquation(bodyA,bodyB), // Normal
        new ContactEquation(bodyA,bodyB), // Tangent2
        new ContactEquation(bodyA,bodyB), // Tangent2
    ];

    var normal = eqs[0];
    var t1 = eqs[1];
    var t2 = eqs[2];

    t1.minForce = t2.minForce = normal.minForce = -maxForce;
    t1.maxForce = t2.maxForce = normal.maxForce =  maxForce;

    // Update
    this.update = function(){
        bodyB.position.vsub(bodyA.position,normal.ni);
        normal.ni.normalize();
        bodyA.quaternion.vmult(pivotA,normal.ri);
        bodyB.quaternion.vmult(pivotB,normal.rj);

        normal.ni.tangents(t1.ni,t2.ni);
        t1.ri.copy(normal.ri);
        t1.rj.copy(normal.rj);
        t2.ri.copy(normal.ri);
        t2.rj.copy(normal.rj);
    };
}
PointToPointConstraint.prototype = new Constraint();