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diff --git a/Source/external/Box2D/Dynamics/Joints/b2MouseJoint.cpp b/Source/external/Box2D/Dynamics/Joints/b2MouseJoint.cpp
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+++ b/Source/external/Box2D/Dynamics/Joints/b2MouseJoint.cpp
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+/*
+* Copyright (c) 2006-2007 Erin Catto http://www.box2d.org
+*
+* 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 as such, and must not be
+* misrepresented as being the original software.
+* 3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "Box2D/Dynamics/Joints/b2MouseJoint.h"
+#include "Box2D/Dynamics/b2Body.h"
+#include "Box2D/Dynamics/b2TimeStep.h"
+
+// p = attached point, m = mouse point
+// C = p - m
+// Cdot = v
+//      = v + cross(w, r)
+// J = [I r_skew]
+// Identity used:
+// w k % (rx i + ry j) = w * (-ry i + rx j)
+
+b2MouseJoint::b2MouseJoint(const b2MouseJointDef* def)
+: b2Joint(def)
+{
+	b2Assert(def->target.IsValid());
+	b2Assert(b2IsValid(def->maxForce) && def->maxForce >= 0.0f);
+	b2Assert(b2IsValid(def->frequencyHz) && def->frequencyHz >= 0.0f);
+	b2Assert(b2IsValid(def->dampingRatio) && def->dampingRatio >= 0.0f);
+
+	m_targetA = def->target;
+	m_localAnchorB = b2MulT(m_bodyB->GetTransform(), m_targetA);
+
+	m_maxForce = def->maxForce;
+	m_impulse.SetZero();
+
+	m_frequencyHz = def->frequencyHz;
+	m_dampingRatio = def->dampingRatio;
+
+	m_beta = 0.0f;
+	m_gamma = 0.0f;
+}
+
+void b2MouseJoint::SetTarget(const b2Vec2& target)
+{
+	if (target != m_targetA)
+	{
+		m_bodyB->SetAwake(true);
+		m_targetA = target;
+	}
+}
+
+const b2Vec2& b2MouseJoint::GetTarget() const
+{
+	return m_targetA;
+}
+
+void b2MouseJoint::SetMaxForce(float32 force)
+{
+	m_maxForce = force;
+}
+
+float32 b2MouseJoint::GetMaxForce() const
+{
+	return m_maxForce;
+}
+
+void b2MouseJoint::SetFrequency(float32 hz)
+{
+	m_frequencyHz = hz;
+}
+
+float32 b2MouseJoint::GetFrequency() const
+{
+	return m_frequencyHz;
+}
+
+void b2MouseJoint::SetDampingRatio(float32 ratio)
+{
+	m_dampingRatio = ratio;
+}
+
+float32 b2MouseJoint::GetDampingRatio() const
+{
+	return m_dampingRatio;
+}
+
+void b2MouseJoint::InitVelocityConstraints(const b2SolverData& data)
+{
+	m_indexB = m_bodyB->m_islandIndex;
+	m_localCenterB = m_bodyB->m_sweep.localCenter;
+	m_invMassB = m_bodyB->m_invMass;
+	m_invIB = m_bodyB->m_invI;
+
+	b2Vec2 cB = data.positions[m_indexB].c;
+	float32 aB = data.positions[m_indexB].a;
+	b2Vec2 vB = data.velocities[m_indexB].v;
+	float32 wB = data.velocities[m_indexB].w;
+
+	b2Rot qB(aB);
+
+	float32 mass = m_bodyB->GetMass();
+
+	// Frequency
+	float32 omega = 2.0f * b2_pi * m_frequencyHz;
+
+	// Damping coefficient
+	float32 d = 2.0f * mass * m_dampingRatio * omega;
+
+	// Spring stiffness
+	float32 k = mass * (omega * omega);
+
+	// magic formulas
+	// gamma has units of inverse mass.
+	// beta has units of inverse time.
+	float32 h = data.step.dt;
+	b2Assert(d + h * k > b2_epsilon);
+	m_gamma = h * (d + h * k);
+	if (m_gamma != 0.0f)
+	{
+		m_gamma = 1.0f / m_gamma;
+	}
+	m_beta = h * k * m_gamma;
+
+	// Compute the effective mass matrix.
+	m_rB = b2Mul(qB, m_localAnchorB - m_localCenterB);
+
+	// K    = [(1/m1 + 1/m2) * eye(2) - skew(r1) * invI1 * skew(r1) - skew(r2) * invI2 * skew(r2)]
+	//      = [1/m1+1/m2     0    ] + invI1 * [r1.y*r1.y -r1.x*r1.y] + invI2 * [r1.y*r1.y -r1.x*r1.y]
+	//        [    0     1/m1+1/m2]           [-r1.x*r1.y r1.x*r1.x]           [-r1.x*r1.y r1.x*r1.x]
+	b2Mat22 K;
+	K.ex.x = m_invMassB + m_invIB * m_rB.y * m_rB.y + m_gamma;
+	K.ex.y = -m_invIB * m_rB.x * m_rB.y;
+	K.ey.x = K.ex.y;
+	K.ey.y = m_invMassB + m_invIB * m_rB.x * m_rB.x + m_gamma;
+
+	m_mass = K.GetInverse();
+
+	m_C = cB + m_rB - m_targetA;
+	m_C *= m_beta;
+
+	// Cheat with some damping
+	wB *= 0.98f;
+
+	if (data.step.warmStarting)
+	{
+		m_impulse *= data.step.dtRatio;
+		vB += m_invMassB * m_impulse;
+		wB += m_invIB * b2Cross(m_rB, m_impulse);
+	}
+	else
+	{
+		m_impulse.SetZero();
+	}
+
+	data.velocities[m_indexB].v = vB;
+	data.velocities[m_indexB].w = wB;
+}
+
+void b2MouseJoint::SolveVelocityConstraints(const b2SolverData& data)
+{
+	b2Vec2 vB = data.velocities[m_indexB].v;
+	float32 wB = data.velocities[m_indexB].w;
+
+	// Cdot = v + cross(w, r)
+	b2Vec2 Cdot = vB + b2Cross(wB, m_rB);
+	b2Vec2 impulse = b2Mul(m_mass, -(Cdot + m_C + m_gamma * m_impulse));
+
+	b2Vec2 oldImpulse = m_impulse;
+	m_impulse += impulse;
+	float32 maxImpulse = data.step.dt * m_maxForce;
+	if (m_impulse.LengthSquared() > maxImpulse * maxImpulse)
+	{
+		m_impulse *= maxImpulse / m_impulse.Length();
+	}
+	impulse = m_impulse - oldImpulse;
+
+	vB += m_invMassB * impulse;
+	wB += m_invIB * b2Cross(m_rB, impulse);
+
+	data.velocities[m_indexB].v = vB;
+	data.velocities[m_indexB].w = wB;
+}
+
+bool b2MouseJoint::SolvePositionConstraints(const b2SolverData& data)
+{
+	B2_NOT_USED(data);
+	return true;
+}
+
+b2Vec2 b2MouseJoint::GetAnchorA() const
+{
+	return m_targetA;
+}
+
+b2Vec2 b2MouseJoint::GetAnchorB() const
+{
+	return m_bodyB->GetWorldPoint(m_localAnchorB);
+}
+
+b2Vec2 b2MouseJoint::GetReactionForce(float32 inv_dt) const
+{
+	return inv_dt * m_impulse;
+}
+
+float32 b2MouseJoint::GetReactionTorque(float32 inv_dt) const
+{
+	return inv_dt * 0.0f;
+}
+
+void b2MouseJoint::ShiftOrigin(const b2Vec2& newOrigin)
+{
+	m_targetA -= newOrigin;
+}