added ConstraintSolver/btConeTwistConstraint.cpp to allow for ragdolls

improved hinge constraint: adds limits
added btAtan2Fast
quaternion helper functions
All thanks to Starbreeze Studios / Marcus Hennix, Marten Svanfeldt

src/BulletDynamics/ConstraintSolver/btConeTwistConstraint.h

@@ -0,0 +1,123 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+btConeTwistConstraint is Copyright (c) 2007 Starbreeze Studios
+
+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.
+
+Written by: Marcus Hennix
+*/
+
+
+
+#ifndef CONETWISTCONSTRAINT_H
+#define CONETWISTCONSTRAINT_H
+
+#include "../../LinearMath/btVector3.h"
+#include "btJacobianEntry.h"
+#include "btTypedConstraint.h"
+
+class btRigidBody;
+
+
+///btConeTwistConstraint can be used to simulate ragdoll joints (upper arm, leg etc)
+class btConeTwistConstraint : public btTypedConstraint
+{
+	btJacobianEntry	m_jac[3]; //3 orthogonal linear constraints
+
+	btTransform m_rbAFrame; 
+	btTransform m_rbBFrame;
+
+	btScalar	m_limitSoftness;
+	btScalar	m_biasFactor;
+	btScalar	m_relaxationFactor;
+
+	btScalar	m_swingSpan1;
+	btScalar	m_swingSpan2;
+	btScalar	m_twistSpan;
+
+	btVector3   m_swingAxis;
+	btVector3	m_twistAxis;
+
+	btScalar	m_kSwing;
+	btScalar	m_kTwist;
+
+	btScalar	m_twistLimitSign;
+	btScalar	m_swingCorrection;
+	btScalar	m_twistCorrection;
+
+	btScalar	m_accSwingLimitImpulse;
+	btScalar	m_accTwistLimitImpulse;
+
+	bool		m_angularOnly;
+	bool		m_solveTwistLimit;
+	bool		m_solveSwingLimit;
+
+	
+public:
+
+	btConeTwistConstraint(btRigidBody& rbA,btRigidBody& rbB,const btTransform& rbAFrame, const btTransform& rbBFrame);
+	
+	btConeTwistConstraint(btRigidBody& rbA,const btTransform& rbAFrame);
+
+	btConeTwistConstraint();
+
+	virtual void	buildJacobian();
+
+	virtual	void	solveConstraint(btScalar	timeStep);
+
+	void	updateRHS(btScalar	timeStep);
+
+	const btRigidBody& getRigidBodyA() const
+	{
+		return m_rbA;
+	}
+	const btRigidBody& getRigidBodyB() const
+	{
+		return m_rbB;
+	}
+
+	void	setAngularOnly(bool angularOnly)
+	{
+		m_angularOnly = angularOnly;
+	}
+
+	void	setLimit(btScalar _swingSpan1,btScalar _swingSpan2,btScalar _twistSpan,  btScalar _softness = 0.8f, btScalar _biasFactor = 0.3f, btScalar _relaxationFactor = 1.0f)
+	{
+		m_swingSpan1 = _swingSpan1;
+		m_swingSpan2 = _swingSpan2;
+		m_twistSpan  = _twistSpan;
+
+		m_limitSoftness =  _softness;
+		m_biasFactor = _biasFactor;
+		m_relaxationFactor = _relaxationFactor;
+	}
+
+	const btTransform& getAFrame() { return m_rbAFrame; };	
+	const btTransform& getBFrame() { return m_rbBFrame; };
+
+	inline int getSolveTwistLimit()
+	{
+		return m_solveTwistLimit;
+	}
+
+	inline int getSolveSwingLimit()
+	{
+		return m_solveTwistLimit;
+	}
+
+	inline btScalar getTwistLimitSign()
+	{
+		return m_twistLimitSign;
+	}
+
+};
+
+#endif //CONETWISTCONSTRAINT_H