btConeTwistConstraint.h

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/*
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
*/



/*
Overview:

btConeTwistConstraint can be used to simulate ragdoll joints (upper arm, leg etc).
It is a fixed translation, 3 degree-of-freedom (DOF) rotational "joint".
It divides the 3 rotational DOFs into swing (movement within a cone) and twist.
Swing is divided into swing1 and swing2 which can have different limits, giving an elliptical shape.
(Note: the cone's base isn't flat, so this ellipse is "embedded" on the surface of a sphere.)

In the contraint's frame of reference:
twist is along the x-axis,
and swing 1 and 2 are along the z and y axes respectively.
*/



#ifndef BT_CONETWISTCONSTRAINT_H
#define BT_CONETWISTCONSTRAINT_H

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

class btRigidBody;

enum btConeTwistFlags
{
        BT_CONETWIST_FLAGS_LIN_CFM = 1,
        BT_CONETWIST_FLAGS_LIN_ERP = 2,
        BT_CONETWIST_FLAGS_ANG_CFM = 4
};

ATTRIBUTE_ALIGNED16(class) btConeTwistConstraint : public btTypedConstraint
{
#ifdef IN_PARALLELL_SOLVER
public:
#endif
        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_damping;

        btScalar        m_swingSpan1;
        btScalar        m_swingSpan2;
        btScalar        m_twistSpan;

        btScalar        m_fixThresh;

        btVector3   m_swingAxis;
        btVector3       m_twistAxis;

        btScalar        m_kSwing;
        btScalar        m_kTwist;

        btScalar        m_twistLimitSign;
        btScalar        m_swingCorrection;
        btScalar        m_twistCorrection;

        btScalar        m_twistAngle;

        btScalar        m_accSwingLimitImpulse;
        btScalar        m_accTwistLimitImpulse;

        bool            m_angularOnly;
        bool            m_solveTwistLimit;
        bool            m_solveSwingLimit;

        bool    m_useSolveConstraintObsolete;

        // not yet used...
        btScalar        m_swingLimitRatio;
        btScalar        m_twistLimitRatio;
        btVector3   m_twistAxisA;

        // motor
        bool             m_bMotorEnabled;
        bool             m_bNormalizedMotorStrength;
        btQuaternion m_qTarget;
        btScalar         m_maxMotorImpulse;
        btVector3        m_accMotorImpulse;
        
        // parameters
        int                     m_flags;
        btScalar        m_linCFM;
        btScalar        m_linERP;
        btScalar        m_angCFM;
        
protected:

        void init();

        void computeConeLimitInfo(const btQuaternion& qCone, // in
                btScalar& swingAngle, btVector3& vSwingAxis, btScalar& swingLimit); // all outs

        void computeTwistLimitInfo(const btQuaternion& qTwist, // in
                btScalar& twistAngle, btVector3& vTwistAxis); // all outs

        void adjustSwingAxisToUseEllipseNormal(btVector3& vSwingAxis) const;


public:

        BT_DECLARE_ALIGNED_ALLOCATOR();

        btConeTwistConstraint(btRigidBody& rbA,btRigidBody& rbB,const btTransform& rbAFrame, const btTransform& rbBFrame);
        
        btConeTwistConstraint(btRigidBody& rbA,const btTransform& rbAFrame);

        virtual void    buildJacobian();

        virtual void getInfo1 (btConstraintInfo1* info);

        void    getInfo1NonVirtual(btConstraintInfo1* info);
        
        virtual void getInfo2 (btConstraintInfo2* info);
        
        void    getInfo2NonVirtual(btConstraintInfo2* info,const btTransform& transA,const btTransform& transB,const btMatrix3x3& invInertiaWorldA,const btMatrix3x3& invInertiaWorldB);

        virtual void    solveConstraintObsolete(btSolverBody& bodyA,btSolverBody& bodyB,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(int limitIndex,btScalar limitValue)
        {
                switch (limitIndex)
                {
                case 3:
                        {
                                m_twistSpan = limitValue;
                                break;
                        }
                case 4:
                        {
                                m_swingSpan2 = limitValue;
                                break;
                        }
                case 5:
                        {
                                m_swingSpan1 = limitValue;
                                break;
                        }
                default:
                        {
                        }
                };
        }

        // setLimit(), a few notes:
        // _softness:
        //              0->1, recommend ~0.8->1.
        //              describes % of limits where movement is free.
        //              beyond this softness %, the limit is gradually enforced until the "hard" (1.0) limit is reached.
        // _biasFactor:
        //              0->1?, recommend 0.3 +/-0.3 or so.
        //              strength with which constraint resists zeroth order (angular, not angular velocity) limit violation.
        // __relaxationFactor:
        //              0->1, recommend to stay near 1.
        //              the lower the value, the less the constraint will fight velocities which violate the angular limits.
        void    setLimit(btScalar _swingSpan1,btScalar _swingSpan2,btScalar _twistSpan, btScalar _softness = 1.f, 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;
        }

        void calcAngleInfo();
        void calcAngleInfo2(const btTransform& transA, const btTransform& transB,const btMatrix3x3& invInertiaWorldA,const btMatrix3x3& invInertiaWorldB);

        inline btScalar getSwingSpan1()
        {
                return m_swingSpan1;
        }
        inline btScalar getSwingSpan2()
        {
                return m_swingSpan2;
        }
        inline btScalar getTwistSpan()
        {
                return m_twistSpan;
        }
        inline btScalar getTwistAngle()
        {
                return m_twistAngle;
        }
        bool isPastSwingLimit() { return m_solveSwingLimit; }

        void setDamping(btScalar damping) { m_damping = damping; }

        void enableMotor(bool b) { m_bMotorEnabled = b; }
        void setMaxMotorImpulse(btScalar maxMotorImpulse) { m_maxMotorImpulse = maxMotorImpulse; m_bNormalizedMotorStrength = false; }
        void setMaxMotorImpulseNormalized(btScalar maxMotorImpulse) { m_maxMotorImpulse = maxMotorImpulse; m_bNormalizedMotorStrength = true; }

        btScalar getFixThresh() { return m_fixThresh; }
        void setFixThresh(btScalar fixThresh) { m_fixThresh = fixThresh; }

        // setMotorTarget:
        // q: the desired rotation of bodyA wrt bodyB.
        // note: if q violates the joint limits, the internal target is clamped to avoid conflicting impulses (very bad for stability)
        // note: don't forget to enableMotor()
        void setMotorTarget(const btQuaternion &q);

        // same as above, but q is the desired rotation of frameA wrt frameB in constraint space
        void setMotorTargetInConstraintSpace(const btQuaternion &q);

        btVector3 GetPointForAngle(btScalar fAngleInRadians, btScalar fLength) const;

        virtual void setParam(int num, btScalar value, int axis = -1);

        virtual void setFrames(const btTransform& frameA, const btTransform& frameB);

        const btTransform& getFrameOffsetA() const
        {
                return m_rbAFrame;
        }

        const btTransform& getFrameOffsetB() const
        {
                return m_rbBFrame;
        }


        virtual btScalar getParam(int num, int axis = -1) const;

        virtual int     calculateSerializeBufferSize() const;

        virtual const char*     serialize(void* dataBuffer, btSerializer* serializer) const;

};

struct  btConeTwistConstraintData
{
        btTypedConstraintData   m_typeConstraintData;
        btTransformFloatData m_rbAFrame;
        btTransformFloatData m_rbBFrame;

        //limits
        float   m_swingSpan1;
        float   m_swingSpan2;
        float   m_twistSpan;
        float   m_limitSoftness;
        float   m_biasFactor;
        float   m_relaxationFactor;

        float   m_damping;
                
        char m_pad[4];

};
        


SIMD_FORCE_INLINE int   btConeTwistConstraint::calculateSerializeBufferSize() const
{
        return sizeof(btConeTwistConstraintData);

}


SIMD_FORCE_INLINE const char*   btConeTwistConstraint::serialize(void* dataBuffer, btSerializer* serializer) const
{
        btConeTwistConstraintData* cone = (btConeTwistConstraintData*) dataBuffer;
        btTypedConstraint::serialize(&cone->m_typeConstraintData,serializer);

        m_rbAFrame.serializeFloat(cone->m_rbAFrame);
        m_rbBFrame.serializeFloat(cone->m_rbBFrame);
        
        cone->m_swingSpan1 = float(m_swingSpan1);
        cone->m_swingSpan2 = float(m_swingSpan2);
        cone->m_twistSpan = float(m_twistSpan);
        cone->m_limitSoftness = float(m_limitSoftness);
        cone->m_biasFactor = float(m_biasFactor);
        cone->m_relaxationFactor = float(m_relaxationFactor);
        cone->m_damping = float(m_damping);

        return "btConeTwistConstraintData";
}


#endif //BT_CONETWISTCONSTRAINT_H