#

API Docs for: 0.6.0
Show: Inherited Protected Private Deprecated

# File: src/equations/RotationalMotorEquation.js

    module.exports = RotationalMotorEquation;

    var Vec3 = require('../math/Vec3');
    var Mat3 = require('../math/Mat3');
    var Equation = require('./Equation');

    /**
     * Rotational motor constraint. Works to keep the relative angular velocity of the bodies to a given value
     * @class RotationalMotorEquation
     * @constructor
     * @author schteppe
     * @param {RigidBody} bodyA
     * @param {RigidBody} bodyB
     * @param {Number} maxForce
     * @extends Equation
     */
    function RotationalMotorEquation(bodyA, bodyB, maxForce){
        maxForce = maxForce || 1e6;
        Equation.call(this,bodyA,bodyB,-maxForce,maxForce);
        this.axisA = new Vec3(); // World oriented rotational axis
        this.axisB = new Vec3(); // World oriented rotational axis

        this.invIi = new Mat3();
        this.invIj = new Mat3();

        /**
         * Motor velocity
         * @property {Number} targetVelocity
         */
        this.targetVelocity = 0;
    }

    RotationalMotorEquation.prototype = new Equation();
    RotationalMotorEquation.prototype.constructor = RotationalMotorEquation;

    var zero = new Vec3();

    RotationalMotorEquation.prototype.computeB = function(h){
        var a = this.a,
            b = this.b,
            bi = this.bi,
            bj = this.bj,

            axisA = this.axisA,
            axisB = this.axisB,

            vi = bi.velocity,
            wi = bi.angularVelocity ? bi.angularVelocity : zero,
            fi = bi.force,
            taui = bi.tau ? bi.tau : zero,

            vj = bj.velocity,
            wj = bj.angularVelocity ? bj.angularVelocity : zero,
            fj = bj.force,
            tauj = bj.tau ? bj.tau : zero,

            GA = this.jacobianElementA,
            GB = this.jacobianElementB,

            invMassi = bi.invMass,
            invMassj = bj.invMass;

        // g = 0
        // gdot = axisA * wi - axisB * wj
        // G = [0 axisA 0 -axisB]
        // W = [vi wi vj wj]

        GA.rotational.copy(axisA);
        axisB.negate(GB.rotational);

        var GW = this.computeGW() - this.targetVelocity,
            GiMf = this.computeGiMf();//axis.dot(invIi.vmult(taui)) + axis.dot(invIj.vmult(tauj));

        var B = - GW * b - h*GiMf;

        return B;
    };

    /*
    // Compute C = GMG+eps
    RotationalMotorEquation.prototype.computeC = function(){
        var bi = this.bi;
        var bj = this.bj;
        var axisA = this.axisA;
        var axisB = this.axisB;
        var invMassi = bi.invMass;
        var invMassj = bj.invMass;

        var C = this.eps;

        C += bi.invInertiaWorld.vmult(axisA).dot(axisB);
        C += bj.invInertiaWorld.vmult(axisB).dot(axisB);

        return C;
    };

    var computeGWlambda_ulambda = new Vec3();
    RotationalMotorEquation.prototype.computeGWlambda = function(){
        var bi = this.bi;
        var bj = this.bj;
        var ulambda = computeGWlambda_ulambda;
        var axisA = this.axisA;
        var axisB = this.axisB;

        var GWlambda = 0.0;
        //bj.vlambda.vsub(bi.vlambda, ulambda);
        //GWlambda += ulambda.dot(this.ni);

        // Angular
        if(bi.wlambda){
            GWlambda += bi.wlambda.dot(axisA);
        }
        if(bj.wlambda){
            GWlambda += bj.wlambda.dot(axisB);
        }

        //console.log("GWlambda:",GWlambda);

        return GWlambda;
    };

    RotationalMotorEquation.prototype.addToWlambda = function(deltalambda){
        var bi = this.bi;
        var bj = this.bj;
        var axisA = this.axisA;
        var axisB = this.axisB;
        var invMassi = bi.invMass;
        var invMassj = bj.invMass;

        // Add to linear velocity
        //bi.vlambda.vsub(n.mult(invMassi * deltalambda),bi.vlambda);
        //bj.vlambda.vadd(n.mult(invMassj * deltalambda),bj.vlambda);

        // Add to angular velocity
        if(bi.wlambda){
            var I = bi.invInertiaWorld;
            bi.wlambda.vsub(I.vmult(axisA).mult(deltalambda),bi.wlambda);
        }
        if(bj.wlambda){
            var I = bj.invInertiaWorld;
            bj.wlambda.vadd(I.vmult(axisB).mult(deltalambda),bj.wlambda);
        }
    };
    */