source: code/branches/physics/src/bullet/BulletDynamics/ConstraintSolver/btHingeConstraint.h @ 1963

/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

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.
*/

/* Hinge Constraint by Dirk Gregorius. Limits added by Marcus Hennix at Starbreeze Studios */

#ifndef HINGECONSTRAINT_H
#define HINGECONSTRAINT_H

#include "LinearMath/btVector3.h"
#include "btJacobianEntry.h"
#include "btTypedConstraint.h"

class btRigidBody;

/// hinge constraint between two rigidbodies each with a pivotpoint that descibes the axis location in local space
/// axis defines the orientation of the hinge axis
class btHingeConstraint : public btTypedConstraint
{
#ifdef IN_PARALLELL_SOLVER
public:
#endif
        btJacobianEntry m_jac[3]; //3 orthogonal linear constraints
        btJacobianEntry m_jacAng[3]; //2 orthogonal angular constraints+ 1 for limit/motor

        btTransform m_rbAFrame; // constraint axii. Assumes z is hinge axis.
        btTransform m_rbBFrame;

        btScalar        m_motorTargetVelocity;
        btScalar        m_maxMotorImpulse;

        btScalar        m_limitSoftness; 
        btScalar        m_biasFactor; 
        btScalar    m_relaxationFactor; 

        btScalar    m_lowerLimit;       
        btScalar    m_upperLimit;       
        
        btScalar        m_kHinge;

        btScalar        m_limitSign;
        btScalar        m_correction;

        btScalar        m_accLimitImpulse;

        bool            m_angularOnly;
        bool            m_enableAngularMotor;
        bool            m_solveLimit;

        
public:

        btHingeConstraint(btRigidBody& rbA,btRigidBody& rbB, const btVector3& pivotInA,const btVector3& pivotInB, btVector3& axisInA,btVector3& axisInB);

        btHingeConstraint(btRigidBody& rbA,const btVector3& pivotInA,btVector3& axisInA);
        
        btHingeConstraint(btRigidBody& rbA,btRigidBody& rbB, const btTransform& rbAFrame, const btTransform& rbBFrame);

        btHingeConstraint(btRigidBody& rbA,const btTransform& rbAFrame);

        btHingeConstraint();

        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    enableAngularMotor(bool enableMotor,btScalar targetVelocity,btScalar maxMotorImpulse)
        {
                m_enableAngularMotor  = enableMotor;
                m_motorTargetVelocity = targetVelocity;
                m_maxMotorImpulse = maxMotorImpulse;
        }

        void    setLimit(btScalar low,btScalar high,btScalar _softness = 0.9f, btScalar _biasFactor = 0.3f, btScalar _relaxationFactor = 1.0f)
        {
                m_lowerLimit = low;
                m_upperLimit = high;

                m_limitSoftness =  _softness;
                m_biasFactor = _biasFactor;
                m_relaxationFactor = _relaxationFactor;

        }

        btScalar        getLowerLimit() const
        {
                return m_lowerLimit;
        }

        btScalar        getUpperLimit() const
        {
                return m_upperLimit;
        }


        btScalar getHingeAngle();


        const btTransform& getAFrame() { return m_rbAFrame; };  
        const btTransform& getBFrame() { return m_rbBFrame; };

        inline int getSolveLimit()
        {
                return m_solveLimit;
        }

        inline btScalar getLimitSign()
        {
                return m_limitSign;
        }

        inline bool getAngularOnly() 
        { 
                return m_angularOnly; 
        }
        inline bool getEnableAngularMotor() 
        { 
                return m_enableAngularMotor; 
        }
        inline btScalar getMotorTargetVelosity() 
        { 
                return m_motorTargetVelocity; 
        }
        inline btScalar getMaxMotorImpulse() 
        { 
                return m_maxMotorImpulse; 
        }

};

#endif //HINGECONSTRAINT_H