p5js/lib/box2d-js/js/box2d/dynamics/joints/b2PrismaticJoint.js

/*
* Copyright (c) 2006-2007 Erin Catto http:
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked, and must not be
* misrepresented the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/





// Linear constraint (point-to-line)
// d = p2 - p1 = x2 + r2 - x1 - r1
// C = dot(ay1, d)
// Cdot = dot(d, cross(w1, ay1)) + dot(ay1, v2 + cross(w2, r2) - v1 - cross(w1, r1))
//      = -dot(ay1, v1) - dot(cross(d + r1, ay1), w1) + dot(ay1, v2) + dot(cross(r2, ay1), v2)
// J = [-ay1 -cross(d+r1,ay1) ay1 cross(r2,ay1)]
//
// Angular constraint
// C = a2 - a1 + a_initial
// Cdot = w2 - w1
// J = [0 0 -1 0 0 1]

// Motor/Limit linear constraint
// C = dot(ax1, d)
// Cdot = = -dot(ax1, v1) - dot(cross(d + r1, ax1), w1) + dot(ax1, v2) + dot(cross(r2, ax1), v2)
// J = [-ax1 -cross(d+r1,ax1) ax1 cross(r2,ax1)]


var b2PrismaticJoint = Class.create();
Object.extend(b2PrismaticJoint.prototype, b2Joint.prototype);
Object.extend(b2PrismaticJoint.prototype, 
{
	GetAnchor1: function(){
		var b1 = this.m_body1;
		//return b2Math.AddVV(b1.m_position, b2Math.b2MulMV(b1.m_R, this.m_localAnchor1));
		var tVec = new b2Vec2();
		tVec.SetV(this.m_localAnchor1);
		tVec.MulM(b1.m_R);
		tVec.Add(b1.m_position);
		return tVec;
	},
	GetAnchor2: function(){
		var b2 = this.m_body2;
		//return b2Math.AddVV(b2.m_position, b2Math.b2MulMV(b2.m_R, this.m_localAnchor2));
		var tVec = new b2Vec2();
		tVec.SetV(this.m_localAnchor2);
		tVec.MulM(b2.m_R);
		tVec.Add(b2.m_position);
		return tVec;
	},
	GetJointTranslation: function(){
		var b1 = this.m_body1;
		var b2 = this.m_body2;

		var tMat;

		//var r1 = b2Math.b2MulMV(b1.m_R, this.m_localAnchor1);
		tMat = b1.m_R;
		var r1X = tMat.col1.x * this.m_localAnchor1.x + tMat.col2.x * this.m_localAnchor1.y;
		var r1Y = tMat.col1.y * this.m_localAnchor1.x + tMat.col2.y * this.m_localAnchor1.y;
		//var r2 = b2Math.b2MulMV(b2.m_R, this.m_localAnchor2);
		tMat = b2.m_R;
		var r2X = tMat.col1.x * this.m_localAnchor2.x + tMat.col2.x * this.m_localAnchor2.y;
		var r2Y = tMat.col1.y * this.m_localAnchor2.x + tMat.col2.y * this.m_localAnchor2.y;
		//var p1 = b2Math.AddVV(b1.m_position , r1);
		var p1X = b1.m_position.x + r1X;
		var p1Y = b1.m_position.y + r1Y;
		//var p2 = b2Math.AddVV(b2.m_position , r2);
		var p2X = b2.m_position.x + r2X;
		var p2Y = b2.m_position.y + r2Y;
		//var d = b2Math.SubtractVV(p2, p1);
		var dX = p2X - p1X;
		var dY = p2Y - p1Y;
		//var ax1 = b2Math.b2MulMV(b1.m_R, this.m_localXAxis1);
		tMat = b1.m_R;
		var ax1X = tMat.col1.x * this.m_localXAxis1.x + tMat.col2.x * this.m_localXAxis1.y;
		var ax1Y = tMat.col1.y * this.m_localXAxis1.x + tMat.col2.y * this.m_localXAxis1.y;

		//var translation = b2Math.b2Dot(ax1, d);
		var translation = ax1X*dX + ax1Y*dY;
		return translation;
	},
	GetJointSpeed: function(){
		var b1 = this.m_body1;
		var b2 = this.m_body2;

		var tMat;

		//var r1 = b2Math.b2MulMV(b1.m_R, this.m_localAnchor1);
		tMat = b1.m_R;
		var r1X = tMat.col1.x * this.m_localAnchor1.x + tMat.col2.x * this.m_localAnchor1.y;
		var r1Y = tMat.col1.y * this.m_localAnchor1.x + tMat.col2.y * this.m_localAnchor1.y;
		//var r2 = b2Math.b2MulMV(b2.m_R, this.m_localAnchor2);
		tMat = b2.m_R;
		var r2X = tMat.col1.x * this.m_localAnchor2.x + tMat.col2.x * this.m_localAnchor2.y;
		var r2Y = tMat.col1.y * this.m_localAnchor2.x + tMat.col2.y * this.m_localAnchor2.y;
		//var p1 = b2Math.AddVV(b1.m_position , r1);
		var p1X = b1.m_position.x + r1X;
		var p1Y = b1.m_position.y + r1Y;
		//var p2 = b2Math.AddVV(b2.m_position , r2);
		var p2X = b2.m_position.x + r2X;
		var p2Y = b2.m_position.y + r2Y;
		//var d = b2Math.SubtractVV(p2, p1);
		var dX = p2X - p1X;
		var dY = p2Y - p1Y;
		//var ax1 = b2Math.b2MulMV(b1.m_R, this.m_localXAxis1);
		tMat = b1.m_R;
		var ax1X = tMat.col1.x * this.m_localXAxis1.x + tMat.col2.x * this.m_localXAxis1.y;
		var ax1Y = tMat.col1.y * this.m_localXAxis1.x + tMat.col2.y * this.m_localXAxis1.y;

		var v1 = b1.m_linearVelocity;
		var v2 = b2.m_linearVelocity;
		var w1 = b1.m_angularVelocity;
		var w2 = b2.m_angularVelocity;

		//var speed = b2Math.b2Dot(d, b2Math.b2CrossFV(w1, ax1)) + b2Math.b2Dot(ax1, b2Math.SubtractVV( b2Math.SubtractVV( b2Math.AddVV( v2 , b2Math.b2CrossFV(w2, r2)) , v1) , b2Math.b2CrossFV(w1, r1)));
		//var b2D = (dX*(-w1 * ax1Y) + dY*(w1 * ax1X));
		//var b2D2 = (ax1X * ((( v2.x + (-w2 * r2Y)) - v1.x) - (-w1 * r1Y)) + ax1Y * ((( v2.y + (w2 * r2X)) - v1.y) - (w1 * r1X)));
		var speed = (dX*(-w1 * ax1Y) + dY*(w1 * ax1X)) + (ax1X * ((( v2.x + (-w2 * r2Y)) - v1.x) - (-w1 * r1Y)) + ax1Y * ((( v2.y + (w2 * r2X)) - v1.y) - (w1 * r1X)));

		return speed;
	},
	GetMotorForce: function(invTimeStep){
		return invTimeStep * this.m_motorImpulse;
	},

	SetMotorSpeed: function(speed)
	{
		this.m_motorSpeed = speed;
	},

	SetMotorForce: function(force)
	{
		this.m_maxMotorForce = force;
	},

	GetReactionForce: function(invTimeStep)
	{
		var tImp = invTimeStep * this.m_limitImpulse;
		var tMat;

		//var ax1 = b2Math.b2MulMV(this.m_body1.m_R, this.m_localXAxis1);
		tMat = this.m_body1.m_R;
		var ax1X = tImp * (tMat.col1.x * this.m_localXAxis1.x + tMat.col2.x * this.m_localXAxis1.y);
		var ax1Y = tImp * (tMat.col1.y * this.m_localXAxis1.x + tMat.col2.y * this.m_localXAxis1.y);
		//var ay1 = b2Math.b2MulMV(this.m_body1.m_R, this.m_localYAxis1);
		var ay1X = tImp * (tMat.col1.x * this.m_localYAxis1.x + tMat.col2.x * this.m_localYAxis1.y);
		var ay1Y = tImp * (tMat.col1.y * this.m_localYAxis1.x + tMat.col2.y * this.m_localYAxis1.y);

		//return (invTimeStep * this.m_limitImpulse) * ax1 + (invTimeStep * this.m_linearImpulse) * ay1;

		return new b2Vec2(ax1X+ay1X, ax1Y+ay1Y);
	},

	GetReactionTorque: function(invTimeStep)
	{
		return invTimeStep * this.m_angularImpulse;
	},


	//--------------- Internals Below -------------------

	initialize: function(def){
		// The constructor for b2Joint
		// initialize instance variables for references
		this.m_node1 = new b2JointNode();
		this.m_node2 = new b2JointNode();
		//
		this.m_type = def.type;
		this.m_prev = null;
		this.m_next = null;
		this.m_body1 = def.body1;
		this.m_body2 = def.body2;
		this.m_collideConnected = def.collideConnected;
		this.m_islandFlag = false;
		this.m_userData = def.userData;
		//

		// initialize instance variables for references
		this.m_localAnchor1 = new b2Vec2();
		this.m_localAnchor2 = new b2Vec2();
		this.m_localXAxis1 = new b2Vec2();
		this.m_localYAxis1 = new b2Vec2();
		this.m_linearJacobian = new b2Jacobian();
		this.m_motorJacobian = new b2Jacobian();
		//

		//super(def);

		var tMat;
		var tX;
		var tY;

		//this.m_localAnchor1 = b2Math.b2MulTMV(this.m_body1.m_R, b2Math.SubtractVV(def.anchorPoint , this.m_body1.m_position));
		tMat = this.m_body1.m_R;
		tX = (def.anchorPoint.x - this.m_body1.m_position.x);
		tY = (def.anchorPoint.y - this.m_body1.m_position.y);
		this.m_localAnchor1.Set((tX*tMat.col1.x + tY*tMat.col1.y), (tX*tMat.col2.x + tY*tMat.col2.y));

		//this.m_localAnchor2 = b2Math.b2MulTMV(this.m_body2.m_R, b2Math.SubtractVV(def.anchorPoint , this.m_body2.m_position));
		tMat = this.m_body2.m_R;
		tX = (def.anchorPoint.x - this.m_body2.m_position.x);
		tY = (def.anchorPoint.y - this.m_body2.m_position.y);
		this.m_localAnchor2.Set((tX*tMat.col1.x + tY*tMat.col1.y), (tX*tMat.col2.x + tY*tMat.col2.y));

		//this.m_localXAxis1 = b2Math.b2MulTMV(this.m_body1.m_R, def.axis);
		tMat = this.m_body1.m_R;
		tX = def.axis.x;
		tY = def.axis.y;
		this.m_localXAxis1.Set((tX*tMat.col1.x + tY*tMat.col1.y), (tX*tMat.col2.x + tY*tMat.col2.y));

		//this.m_localYAxis1 = b2Math.b2CrossFV(1.0, this.m_localXAxis1);
		this.m_localYAxis1.x = -this.m_localXAxis1.y;
		this.m_localYAxis1.y = this.m_localXAxis1.x;

		this.m_initialAngle = this.m_body2.m_rotation - this.m_body1.m_rotation;

		this.m_linearJacobian.SetZero();
		this.m_linearMass = 0.0;
		this.m_linearImpulse = 0.0;

		this.m_angularMass = 0.0;
		this.m_angularImpulse = 0.0;

		this.m_motorJacobian.SetZero();
		this.m_motorMass = 0.0;
		this.m_motorImpulse = 0.0;
		this.m_limitImpulse = 0.0;
		this.m_limitPositionImpulse = 0.0;

		this.m_lowerTranslation = def.lowerTranslation;
		this.m_upperTranslation = def.upperTranslation;
		this.m_maxMotorForce = def.motorForce;
		this.m_motorSpeed = def.motorSpeed;
		this.m_enableLimit = def.enableLimit;
		this.m_enableMotor = def.enableMotor;
	},

	PrepareVelocitySolver: function(){
		var b1 = this.m_body1;
		var b2 = this.m_body2;

		var tMat;

		// Compute the effective masses.
		//b2Vec2 r1 = b2Mul(b1->m_R, this.m_localAnchor1);
		tMat = b1.m_R;
		var r1X = tMat.col1.x * this.m_localAnchor1.x + tMat.col2.x * this.m_localAnchor1.y;
		var r1Y = tMat.col1.y * this.m_localAnchor1.x + tMat.col2.y * this.m_localAnchor1.y;
		//b2Vec2 r2 = b2Mul(b2->m_R, this.m_localAnchor2);
		tMat = b2.m_R;
		var r2X = tMat.col1.x * this.m_localAnchor2.x + tMat.col2.x * this.m_localAnchor2.y;
		var r2Y = tMat.col1.y * this.m_localAnchor2.x + tMat.col2.y * this.m_localAnchor2.y;

		//float32 invMass1 = b1->m_invMass, invMass2 = b2->m_invMass;
		var invMass1 = b1.m_invMass;
		var invMass2 = b2.m_invMass;
		//float32 invI1 = b1->m_invI, invI2 = b2->m_invI;
		var invI1 = b1.m_invI;
		var invI2 = b2.m_invI;

		// Compute point to line constraint effective mass.
		// J = [-ay1 -cross(d+r1,ay1) ay1 cross(r2,ay1)]
		//b2Vec2 ay1 = b2Mul(b1->m_R, this.m_localYAxis1);
		tMat = b1.m_R;
		var ay1X = tMat.col1.x * this.m_localYAxis1.x + tMat.col2.x * this.m_localYAxis1.y;
		var ay1Y = tMat.col1.y * this.m_localYAxis1.x + tMat.col2.y * this.m_localYAxis1.y;
		//b2Vec2 e = b2->m_position + r2 - b1->m_position;
		var eX = b2.m_position.x + r2X - b1.m_position.x;
		var eY = b2.m_position.y + r2Y - b1.m_position.y;

		//this.m_linearJacobian.Set(-ay1, -b2Math.b2Cross(e, ay1), ay1, b2Math.b2Cross(r2, ay1));
		this.m_linearJacobian.linear1.x = -ay1X;
		this.m_linearJacobian.linear1.y = -ay1Y;
		this.m_linearJacobian.linear2.x = ay1X;
		this.m_linearJacobian.linear2.y = ay1Y;
		this.m_linearJacobian.angular1 = -(eX * ay1Y - eY * ay1X);
		this.m_linearJacobian.angular2 = r2X * ay1Y - r2Y * ay1X;

		this.m_linearMass =	invMass1 + invI1 * this.m_linearJacobian.angular1 * this.m_linearJacobian.angular1 +
						invMass2 + invI2 * this.m_linearJacobian.angular2 * this.m_linearJacobian.angular2;
		//b2Settings.b2Assert(this.m_linearMass > Number.MIN_VALUE);
		this.m_linearMass = 1.0 / this.m_linearMass;

		// Compute angular constraint effective mass.
		this.m_angularMass = 1.0 / (invI1 + invI2);

		// Compute motor and limit terms.
		if (this.m_enableLimit || this.m_enableMotor)
		{
			// The motor and limit share a Jacobian and effective mass.
			//b2Vec2 ax1 = b2Mul(b1->m_R, this.m_localXAxis1);
			tMat = b1.m_R;
			var ax1X = tMat.col1.x * this.m_localXAxis1.x + tMat.col2.x * this.m_localXAxis1.y;
			var ax1Y = tMat.col1.y * this.m_localXAxis1.x + tMat.col2.y * this.m_localXAxis1.y;
			//this.m_motorJacobian.Set(-ax1, -b2Cross(e, ax1), ax1, b2Cross(r2, ax1));
			this.m_motorJacobian.linear1.x = -ax1X; this.m_motorJacobian.linear1.y = -ax1Y;
			this.m_motorJacobian.linear2.x = ax1X; this.m_motorJacobian.linear2.y = ax1Y;
			this.m_motorJacobian.angular1 = -(eX * ax1Y - eY * ax1X);
			this.m_motorJacobian.angular2 = r2X * ax1Y - r2Y * ax1X;

			this.m_motorMass =	invMass1 + invI1 * this.m_motorJacobian.angular1 * this.m_motorJacobian.angular1 +
							invMass2 + invI2 * this.m_motorJacobian.angular2 * this.m_motorJacobian.angular2;
			//b2Settings.b2Assert(this.m_motorMass > Number.MIN_VALUE);
			this.m_motorMass = 1.0 / this.m_motorMass;

			if (this.m_enableLimit)
			{
				//b2Vec2 d = e - r1;
				var dX = eX - r1X;
				var dY = eY - r1Y;
				//float32 jointTranslation = b2Dot(ax1, d);
				var jointTranslation = ax1X * dX + ax1Y * dY;
				if (b2Math.b2Abs(this.m_upperTranslation - this.m_lowerTranslation) < 2.0 * b2Settings.b2_linearSlop)
				{
					this.m_limitState = b2Joint.e_equalLimits;
				}
				else if (jointTranslation <= this.m_lowerTranslation)
				{
					if (this.m_limitState != b2Joint.e_atLowerLimit)
					{
						this.m_limitImpulse = 0.0;
					}
					this.m_limitState = b2Joint.e_atLowerLimit;
				}
				else if (jointTranslation >= this.m_upperTranslation)
				{
					if (this.m_limitState != b2Joint.e_atUpperLimit)
					{
						this.m_limitImpulse = 0.0;
					}
					this.m_limitState = b2Joint.e_atUpperLimit;
				}
				else
				{
					this.m_limitState = b2Joint.e_inactiveLimit;
					this.m_limitImpulse = 0.0;
				}
			}
		}

		if (this.m_enableMotor == false)
		{
			this.m_motorImpulse = 0.0;
		}

		if (this.m_enableLimit == false)
		{
			this.m_limitImpulse = 0.0;
		}

		if (b2World.s_enableWarmStarting)
		{
			//b2Vec2 P1 = this.m_linearImpulse * this.m_linearJacobian.linear1 + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.linear1;
			var P1X = this.m_linearImpulse * this.m_linearJacobian.linear1.x + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.linear1.x;
			var P1Y = this.m_linearImpulse * this.m_linearJacobian.linear1.y + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.linear1.y;
			//b2Vec2 P2 = this.m_linearImpulse * this.m_linearJacobian.linear2 + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.linear2;
			var P2X = this.m_linearImpulse * this.m_linearJacobian.linear2.x + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.linear2.x;
			var P2Y = this.m_linearImpulse * this.m_linearJacobian.linear2.y + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.linear2.y;
			//float32 L1 = this.m_linearImpulse * this.m_linearJacobian.angular1 - this.m_angularImpulse + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.angular1;
			var L1 = this.m_linearImpulse * this.m_linearJacobian.angular1 - this.m_angularImpulse + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.angular1;
			//float32 L2 = this.m_linearImpulse * this.m_linearJacobian.angular2 + this.m_angularImpulse + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.angular2;
			var L2 = this.m_linearImpulse * this.m_linearJacobian.angular2 + this.m_angularImpulse + (this.m_motorImpulse + this.m_limitImpulse) * this.m_motorJacobian.angular2;

			//b1->m_linearVelocity += invMass1 * P1;
			b1.m_linearVelocity.x += invMass1 * P1X;
			b1.m_linearVelocity.y += invMass1 * P1Y;
			//b1->m_angularVelocity += invI1 * L1;
			b1.m_angularVelocity += invI1 * L1;

			//b2->m_linearVelocity += invMass2 * P2;
			b2.m_linearVelocity.x += invMass2 * P2X;
			b2.m_linearVelocity.y += invMass2 * P2Y;
			//b2->m_angularVelocity += invI2 * L2;
			b2.m_angularVelocity += invI2 * L2;
		}
		else
		{
			this.m_linearImpulse = 0.0;
			this.m_angularImpulse = 0.0;
			this.m_limitImpulse = 0.0;
			this.m_motorImpulse = 0.0;
		}

		this.m_limitPositionImpulse = 0.0;

	},

	SolveVelocityConstraints: function(step){
		var b1 = this.m_body1;
		var b2 = this.m_body2;

		var invMass1 = b1.m_invMass;
		var invMass2 = b2.m_invMass;
		var invI1 = b1.m_invI;
		var invI2 = b2.m_invI;

		var oldLimitImpulse;

		// Solve linear constraint.
		var linearCdot = this.m_linearJacobian.Compute(b1.m_linearVelocity, b1.m_angularVelocity, b2.m_linearVelocity, b2.m_angularVelocity);
		var linearImpulse = -this.m_linearMass * linearCdot;
		this.m_linearImpulse += linearImpulse;

		//b1->m_linearVelocity += (invMass1 * linearImpulse) * this.m_linearJacobian.linear1;
		b1.m_linearVelocity.x += (invMass1 * linearImpulse) * this.m_linearJacobian.linear1.x;
		b1.m_linearVelocity.y += (invMass1 * linearImpulse) * this.m_linearJacobian.linear1.y;
		//b1->m_angularVelocity += invI1 * linearImpulse * this.m_linearJacobian.angular1;
		b1.m_angularVelocity += invI1 * linearImpulse * this.m_linearJacobian.angular1;

		//b2->m_linearVelocity += (invMass2 * linearImpulse) * this.m_linearJacobian.linear2;
		b2.m_linearVelocity.x += (invMass2 * linearImpulse) * this.m_linearJacobian.linear2.x;
		b2.m_linearVelocity.y += (invMass2 * linearImpulse) * this.m_linearJacobian.linear2.y;
		//b2.m_angularVelocity += invI2 * linearImpulse * this.m_linearJacobian.angular2;
		b2.m_angularVelocity += invI2 * linearImpulse * this.m_linearJacobian.angular2;

		// Solve angular constraint.
		var angularCdot = b2.m_angularVelocity - b1.m_angularVelocity;
		var angularImpulse = -this.m_angularMass * angularCdot;
		this.m_angularImpulse += angularImpulse;

		b1.m_angularVelocity -= invI1 * angularImpulse;
		b2.m_angularVelocity += invI2 * angularImpulse;

		// Solve linear motor constraint.
		if (this.m_enableMotor && this.m_limitState != b2Joint.e_equalLimits)
		{
			var motorCdot = this.m_motorJacobian.Compute(b1.m_linearVelocity, b1.m_angularVelocity, b2.m_linearVelocity, b2.m_angularVelocity) - this.m_motorSpeed;
			var motorImpulse = -this.m_motorMass * motorCdot;
			var oldMotorImpulse = this.m_motorImpulse;
			this.m_motorImpulse = b2Math.b2Clamp(this.m_motorImpulse + motorImpulse, -step.dt * this.m_maxMotorForce, step.dt * this.m_maxMotorForce);
			motorImpulse = this.m_motorImpulse - oldMotorImpulse;

			//b1.m_linearVelocity += (invMass1 * motorImpulse) * this.m_motorJacobian.linear1;
			b1.m_linearVelocity.x += (invMass1 * motorImpulse) * this.m_motorJacobian.linear1.x;
			b1.m_linearVelocity.y += (invMass1 * motorImpulse) * this.m_motorJacobian.linear1.y;
			//b1.m_angularVelocity += invI1 * motorImpulse * this.m_motorJacobian.angular1;
			b1.m_angularVelocity += invI1 * motorImpulse * this.m_motorJacobian.angular1;

			//b2->m_linearVelocity += (invMass2 * motorImpulse) * this.m_motorJacobian.linear2;
			b2.m_linearVelocity.x += (invMass2 * motorImpulse) * this.m_motorJacobian.linear2.x;
			b2.m_linearVelocity.y += (invMass2 * motorImpulse) * this.m_motorJacobian.linear2.y;
			//b2->m_angularVelocity += invI2 * motorImpulse * this.m_motorJacobian.angular2;
			b2.m_angularVelocity += invI2 * motorImpulse * this.m_motorJacobian.angular2;
		}

		// Solve linear limit constraint.
		if (this.m_enableLimit && this.m_limitState != b2Joint.e_inactiveLimit)
		{
			var limitCdot = this.m_motorJacobian.Compute(b1.m_linearVelocity, b1.m_angularVelocity, b2.m_linearVelocity, b2.m_angularVelocity);
			var limitImpulse = -this.m_motorMass * limitCdot;

			if (this.m_limitState == b2Joint.e_equalLimits)
			{
				this.m_limitImpulse += limitImpulse;
			}
			else if (this.m_limitState == b2Joint.e_atLowerLimit)
			{
				oldLimitImpulse = this.m_limitImpulse;
				this.m_limitImpulse = b2Math.b2Max(this.m_limitImpulse + limitImpulse, 0.0);
				limitImpulse = this.m_limitImpulse - oldLimitImpulse;
			}
			else if (this.m_limitState == b2Joint.e_atUpperLimit)
			{
				oldLimitImpulse = this.m_limitImpulse;
				this.m_limitImpulse = b2Math.b2Min(this.m_limitImpulse + limitImpulse, 0.0);
				limitImpulse = this.m_limitImpulse - oldLimitImpulse;
			}

			//b1->m_linearVelocity += (invMass1 * limitImpulse) * this.m_motorJacobian.linear1;
			b1.m_linearVelocity.x += (invMass1 * limitImpulse) * this.m_motorJacobian.linear1.x;
			b1.m_linearVelocity.y += (invMass1 * limitImpulse) * this.m_motorJacobian.linear1.y;
			//b1->m_angularVelocity += invI1 * limitImpulse * this.m_motorJacobian.angular1;
			b1.m_angularVelocity += invI1 * limitImpulse * this.m_motorJacobian.angular1;

			//b2->m_linearVelocity += (invMass2 * limitImpulse) * this.m_motorJacobian.linear2;
			b2.m_linearVelocity.x += (invMass2 * limitImpulse) * this.m_motorJacobian.linear2.x;
			b2.m_linearVelocity.y += (invMass2 * limitImpulse) * this.m_motorJacobian.linear2.y;
			//b2->m_angularVelocity += invI2 * limitImpulse * this.m_motorJacobian.angular2;
			b2.m_angularVelocity += invI2 * limitImpulse * this.m_motorJacobian.angular2;
		}
	},



	SolvePositionConstraints: function(){

		var limitC;
		var oldLimitImpulse;

		var b1 = this.m_body1;
		var b2 = this.m_body2;

		var invMass1 = b1.m_invMass;
		var invMass2 = b2.m_invMass;
		var invI1 = b1.m_invI;
		var invI2 = b2.m_invI;

		var tMat;

		//b2Vec2 r1 = b2Mul(b1->m_R, this.m_localAnchor1);
		tMat = b1.m_R;
		var r1X = tMat.col1.x * this.m_localAnchor1.x + tMat.col2.x * this.m_localAnchor1.y;
		var r1Y = tMat.col1.y * this.m_localAnchor1.x + tMat.col2.y * this.m_localAnchor1.y;
		//b2Vec2 r2 = b2Mul(b2->m_R, this.m_localAnchor2);
		tMat = b2.m_R;
		var r2X = tMat.col1.x * this.m_localAnchor2.x + tMat.col2.x * this.m_localAnchor2.y;
		var r2Y = tMat.col1.y * this.m_localAnchor2.x + tMat.col2.y * this.m_localAnchor2.y;
		//b2Vec2 p1 = b1->m_position + r1;
		var p1X = b1.m_position.x + r1X;
		var p1Y = b1.m_position.y + r1Y;
		//b2Vec2 p2 = b2->m_position + r2;
		var p2X = b2.m_position.x + r2X;
		var p2Y = b2.m_position.y + r2Y;
		//b2Vec2 d = p2 - p1;
		var dX = p2X - p1X;
		var dY = p2Y - p1Y;
		//b2Vec2 ay1 = b2Mul(b1->m_R, this.m_localYAxis1);
		tMat = b1.m_R;
		var ay1X = tMat.col1.x * this.m_localYAxis1.x + tMat.col2.x * this.m_localYAxis1.y;
		var ay1Y = tMat.col1.y * this.m_localYAxis1.x + tMat.col2.y * this.m_localYAxis1.y;

		// Solve linear (point-to-line) constraint.
		//float32 linearC = b2Dot(ay1, d);
		var linearC = ay1X*dX + ay1Y*dY;
		// Prevent overly large corrections.
		linearC = b2Math.b2Clamp(linearC, -b2Settings.b2_maxLinearCorrection, b2Settings.b2_maxLinearCorrection);
		var linearImpulse = -this.m_linearMass * linearC;

		//b1->m_position += (invMass1 * linearImpulse) * this.m_linearJacobian.linear1;
		b1.m_position.x += (invMass1 * linearImpulse) * this.m_linearJacobian.linear1.x;
		b1.m_position.y += (invMass1 * linearImpulse) * this.m_linearJacobian.linear1.y;
		//b1->m_rotation += invI1 * linearImpulse * this.m_linearJacobian.angular1;
		b1.m_rotation += invI1 * linearImpulse * this.m_linearJacobian.angular1;
		//b1->m_R.Set(b1->m_rotation);
		//b2->m_position += (invMass2 * linearImpulse) * this.m_linearJacobian.linear2;
		b2.m_position.x += (invMass2 * linearImpulse) * this.m_linearJacobian.linear2.x;
		b2.m_position.y += (invMass2 * linearImpulse) * this.m_linearJacobian.linear2.y;
		b2.m_rotation += invI2 * linearImpulse * this.m_linearJacobian.angular2;
		//b2->m_R.Set(b2->m_rotation);

		var positionError = b2Math.b2Abs(linearC);

		// Solve angular constraint.
		var angularC = b2.m_rotation - b1.m_rotation - this.m_initialAngle;
		// Prevent overly large corrections.
		angularC = b2Math.b2Clamp(angularC, -b2Settings.b2_maxAngularCorrection, b2Settings.b2_maxAngularCorrection);
		var angularImpulse = -this.m_angularMass * angularC;

		b1.m_rotation -= b1.m_invI * angularImpulse;
		b1.m_R.Set(b1.m_rotation);
		b2.m_rotation += b2.m_invI * angularImpulse;
		b2.m_R.Set(b2.m_rotation);

		var angularError = b2Math.b2Abs(angularC);

		// Solve linear limit constraint.
		if (this.m_enableLimit && this.m_limitState != b2Joint.e_inactiveLimit)
		{

			//b2Vec2 r1 = b2Mul(b1->m_R, this.m_localAnchor1);
			tMat = b1.m_R;
			r1X = tMat.col1.x * this.m_localAnchor1.x + tMat.col2.x * this.m_localAnchor1.y;
			r1Y = tMat.col1.y * this.m_localAnchor1.x + tMat.col2.y * this.m_localAnchor1.y;
			//b2Vec2 r2 = b2Mul(b2->m_R, this.m_localAnchor2);
			tMat = b2.m_R;
			r2X = tMat.col1.x * this.m_localAnchor2.x + tMat.col2.x * this.m_localAnchor2.y;
			r2Y = tMat.col1.y * this.m_localAnchor2.x + tMat.col2.y * this.m_localAnchor2.y;
			//b2Vec2 p1 = b1->m_position + r1;
			p1X = b1.m_position.x + r1X;
			p1Y = b1.m_position.y + r1Y;
			//b2Vec2 p2 = b2->m_position + r2;
			p2X = b2.m_position.x + r2X;
			p2Y = b2.m_position.y + r2Y;
			//b2Vec2 d = p2 - p1;
			dX = p2X - p1X;
			dY = p2Y - p1Y;
			//b2Vec2 ax1 = b2Mul(b1->m_R, this.m_localXAxis1);
			tMat = b1.m_R;
			var ax1X = tMat.col1.x * this.m_localXAxis1.x + tMat.col2.x * this.m_localXAxis1.y;
			var ax1Y = tMat.col1.y * this.m_localXAxis1.x + tMat.col2.y * this.m_localXAxis1.y;

			//float32 translation = b2Dot(ax1, d);
			var translation = (ax1X*dX + ax1Y*dY);
			var limitImpulse = 0.0;

			if (this.m_limitState == b2Joint.e_equalLimits)
			{
				// Prevent large angular corrections
				limitC = b2Math.b2Clamp(translation, -b2Settings.b2_maxLinearCorrection, b2Settings.b2_maxLinearCorrection);
				limitImpulse = -this.m_motorMass * limitC;
				positionError = b2Math.b2Max(positionError, b2Math.b2Abs(angularC));
			}
			else if (this.m_limitState == b2Joint.e_atLowerLimit)
			{
				limitC = translation - this.m_lowerTranslation;
				positionError = b2Math.b2Max(positionError, -limitC);

				// Prevent large linear corrections and allow some slop.
				limitC = b2Math.b2Clamp(limitC + b2Settings.b2_linearSlop, -b2Settings.b2_maxLinearCorrection, 0.0);
				limitImpulse = -this.m_motorMass * limitC;
				oldLimitImpulse = this.m_limitPositionImpulse;
				this.m_limitPositionImpulse = b2Math.b2Max(this.m_limitPositionImpulse + limitImpulse, 0.0);
				limitImpulse = this.m_limitPositionImpulse - oldLimitImpulse;
			}
			else if (this.m_limitState == b2Joint.e_atUpperLimit)
			{
				limitC = translation - this.m_upperTranslation;
				positionError = b2Math.b2Max(positionError, limitC);

				// Prevent large linear corrections and allow some slop.
				limitC = b2Math.b2Clamp(limitC - b2Settings.b2_linearSlop, 0.0, b2Settings.b2_maxLinearCorrection);
				limitImpulse = -this.m_motorMass * limitC;
				oldLimitImpulse = this.m_limitPositionImpulse;
				this.m_limitPositionImpulse = b2Math.b2Min(this.m_limitPositionImpulse + limitImpulse, 0.0);
				limitImpulse = this.m_limitPositionImpulse - oldLimitImpulse;
			}

			//b1->m_position += (invMass1 * limitImpulse) * this.m_motorJacobian.linear1;
			b1.m_position.x += (invMass1 * limitImpulse) * this.m_motorJacobian.linear1.x;
			b1.m_position.y += (invMass1 * limitImpulse) * this.m_motorJacobian.linear1.y;
			//b1->m_rotation += invI1 * limitImpulse * this.m_motorJacobian.angular1;
			b1.m_rotation += invI1 * limitImpulse * this.m_motorJacobian.angular1;
			b1.m_R.Set(b1.m_rotation);
			//b2->m_position += (invMass2 * limitImpulse) * this.m_motorJacobian.linear2;
			b2.m_position.x += (invMass2 * limitImpulse) * this.m_motorJacobian.linear2.x;
			b2.m_position.y += (invMass2 * limitImpulse) * this.m_motorJacobian.linear2.y;
			//b2->m_rotation += invI2 * limitImpulse * this.m_motorJacobian.angular2;
			b2.m_rotation += invI2 * limitImpulse * this.m_motorJacobian.angular2;
			b2.m_R.Set(b2.m_rotation);
		}

		return positionError <= b2Settings.b2_linearSlop && angularError <= b2Settings.b2_angularSlop;

	},

	m_localAnchor1: new b2Vec2(),
	m_localAnchor2: new b2Vec2(),
	m_localXAxis1: new b2Vec2(),
	m_localYAxis1: new b2Vec2(),
	m_initialAngle: null,

	m_linearJacobian: new b2Jacobian(),
	m_linearMass: null,
	m_linearImpulse: null,

	m_angularMass: null,
	m_angularImpulse: null,

	m_motorJacobian: new b2Jacobian(),
	m_motorMass: null,
	m_motorImpulse: null,
	m_limitImpulse: null,
	m_limitPositionImpulse: null,

	m_lowerTranslation: null,
	m_upperTranslation: null,
	m_maxMotorForce: null,
	m_motorSpeed: null,

	m_enableLimit: null,
	m_enableMotor: null,
	m_limitState: 0});