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diff --git a/Source/external/Box2D/Dynamics/Joints/b2WeldJoint.h b/Source/external/Box2D/Dynamics/Joints/b2WeldJoint.h
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+/*
+* Copyright (c) 2006-2011 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.
+*/
+
+#ifndef B2_WELD_JOINT_H
+#define B2_WELD_JOINT_H
+
+#include "Box2D/Dynamics/Joints/b2Joint.h"
+
+/// Weld joint definition. You need to specify local anchor points
+/// where they are attached and the relative body angle. The position
+/// of the anchor points is important for computing the reaction torque.
+struct b2WeldJointDef : public b2JointDef
+{
+	b2WeldJointDef()
+	{
+		type = e_weldJoint;
+		localAnchorA.Set(0.0f, 0.0f);
+		localAnchorB.Set(0.0f, 0.0f);
+		referenceAngle = 0.0f;
+		frequencyHz = 0.0f;
+		dampingRatio = 0.0f;
+	}
+
+	/// Initialize the bodies, anchors, and reference angle using a world
+	/// anchor point.
+	void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
+
+	/// The local anchor point relative to bodyA's origin.
+	b2Vec2 localAnchorA;
+
+	/// The local anchor point relative to bodyB's origin.
+	b2Vec2 localAnchorB;
+
+	/// The bodyB angle minus bodyA angle in the reference state (radians).
+	float32 referenceAngle;
+	
+	/// The mass-spring-damper frequency in Hertz. Rotation only.
+	/// Disable softness with a value of 0.
+	float32 frequencyHz;
+
+	/// The damping ratio. 0 = no damping, 1 = critical damping.
+	float32 dampingRatio;
+};
+
+/// A weld joint essentially glues two bodies together. A weld joint may
+/// distort somewhat because the island constraint solver is approximate.
+class b2WeldJoint : public b2Joint
+{
+public:
+	b2Vec2 GetAnchorA() const override;
+	b2Vec2 GetAnchorB() const override;
+
+	b2Vec2 GetReactionForce(float32 inv_dt) const override;
+	float32 GetReactionTorque(float32 inv_dt) const override;
+
+	/// The local anchor point relative to bodyA's origin.
+	const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
+
+	/// The local anchor point relative to bodyB's origin.
+	const b2Vec2& GetLocalAnchorB() const  { return m_localAnchorB; }
+
+	/// Get the reference angle.
+	float32 GetReferenceAngle() const { return m_referenceAngle; }
+
+	/// Set/get frequency in Hz.
+	void SetFrequency(float32 hz) { m_frequencyHz = hz; }
+	float32 GetFrequency() const { return m_frequencyHz; }
+
+	/// Set/get damping ratio.
+	void SetDampingRatio(float32 ratio) { m_dampingRatio = ratio; }
+	float32 GetDampingRatio() const { return m_dampingRatio; }
+
+	/// Dump to b2Log
+	void Dump() override;
+
+protected:
+
+	friend class b2Joint;
+
+	b2WeldJoint(const b2WeldJointDef* def);
+
+	void InitVelocityConstraints(const b2SolverData& data) override;
+	void SolveVelocityConstraints(const b2SolverData& data) override;
+	bool SolvePositionConstraints(const b2SolverData& data) override;
+
+	float32 m_frequencyHz;
+	float32 m_dampingRatio;
+	float32 m_bias;
+
+	// Solver shared
+	b2Vec2 m_localAnchorA;
+	b2Vec2 m_localAnchorB;
+	float32 m_referenceAngle;
+	float32 m_gamma;
+	b2Vec3 m_impulse;
+
+	// Solver temp
+	int32 m_indexA;
+	int32 m_indexB;
+	b2Vec2 m_rA;
+	b2Vec2 m_rB;
+	b2Vec2 m_localCenterA;
+	b2Vec2 m_localCenterB;
+	float32 m_invMassA;
+	float32 m_invMassB;
+	float32 m_invIA;
+	float32 m_invIB;
+	b2Mat33 m_mass;
+};
+
+#endif