function LinearConstraint ( joint ){

	    this.m1=NaN;
	    this.m2=NaN;

	    this.ii1 = null;
	    this.ii2 = null;
	    this.dd = null;

	    this.r1x=NaN;
	    this.r1y=NaN;
	    this.r1z=NaN;

	    this.r2x=NaN;
	    this.r2y=NaN;
	    this.r2z=NaN;

	    this.ax1x=NaN;
	    this.ax1y=NaN;
	    this.ax1z=NaN;
	    this.ay1x=NaN;
	    this.ay1y=NaN;
	    this.ay1z=NaN;
	    this.az1x=NaN;
	    this.az1y=NaN;
	    this.az1z=NaN;

	    this.ax2x=NaN;
	    this.ax2y=NaN;
	    this.ax2z=NaN;
	    this.ay2x=NaN;
	    this.ay2y=NaN;
	    this.ay2z=NaN;
	    this.az2x=NaN;
	    this.az2y=NaN;
	    this.az2z=NaN;

	    this.vel=NaN;
	    this.velx=NaN;
	    this.vely=NaN;
	    this.velz=NaN;


	    this.joint = joint;
	    this.r1 = joint.relativeAnchorPoint1;
	    this.r2 = joint.relativeAnchorPoint2;
	    this.p1 = joint.anchorPoint1;
	    this.p2 = joint.anchorPoint2;
	    this.b1 = joint.body1;
	    this.b2 = joint.body2;
	    this.l1 = this.b1.linearVelocity;
	    this.l2 = this.b2.linearVelocity;
	    this.a1 = this.b1.angularVelocity;
	    this.a2 = this.b2.angularVelocity;
	    this.i1 = this.b1.inverseInertia;
	    this.i2 = this.b2.inverseInertia;
	    this.impx = 0;
	    this.impy = 0;
	    this.impz = 0;

	}
A linear constraint for all axes for various joints.
@author saharan