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"
 
#ifdef BT_USE_DOUBLE_PRECISION
#define btConeTwistConstraintData2 btConeTwistConstraintDoubleData
#define btConeTwistConstraintDataName "btConeTwistConstraintDoubleData"
#else
#define btConeTwistConstraintData2 btConeTwistConstraintData
#define btConeTwistConstraintDataName "btConeTwistConstraintData"
#endif  //BT_USE_DOUBLE_PRECISION
 
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;
        }
 
        bool getAngularOnly() const
        {
                return m_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:
                        {
                        }
                };
        }
 
        btScalar getLimit(int limitIndex) const
        {
                switch (limitIndex)
                {
                        case 3:
                        {
                                return m_twistSpan;
                                break;
                        }
                        case 4:
                        {
                                return m_swingSpan2;
                                break;
                        }
                        case 5:
                        {
                                return m_swingSpan1;
                                break;
                        }
                        default:
                        {
                                btAssert(0 && "Invalid limitIndex specified for btConeTwistConstraint");
                                return 0.0;
                        }
                };
        }
 
        // 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() const { return m_rbAFrame; };
        const btTransform& getBFrame() const { return m_rbBFrame; };
 
        inline int getSolveTwistLimit()
        {
                return m_solveTwistLimit;
        }
 
        inline int getSolveSwingLimit()
        {
                return m_solveSwingLimit;
        }
 
        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() const
        {
                return m_swingSpan1;
        }
        inline btScalar getSwingSpan2() const
        {
                return m_swingSpan2;
        }
        inline btScalar getTwistSpan() const
        {
                return m_twistSpan;
        }
        inline btScalar getLimitSoftness() const
        {
                return m_limitSoftness;
        }
        inline btScalar getBiasFactor() const
        {
                return m_biasFactor;
        }
        inline btScalar getRelaxationFactor() const
        {
                return m_relaxationFactor;
        }
        inline btScalar getTwistAngle() const
        {
                return m_twistAngle;
        }
        bool isPastSwingLimit() { return m_solveSwingLimit; }
 
        btScalar getDamping() const { return m_damping; }
        void setDamping(btScalar damping) { m_damping = damping; }
 
        void enableMotor(bool b) { m_bMotorEnabled = b; }
        bool isMotorEnabled() const { return m_bMotorEnabled; }
        btScalar getMaxMotorImpulse() const { return m_maxMotorImpulse; }
        bool isMaxMotorImpulseNormalized() const { return m_bNormalizedMotorStrength; }
        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);
        const btQuaternion& getMotorTarget() const { return m_qTarget; }
 
        // 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;
 
        int getFlags() const
        {
                return m_flags;
        }
 
        virtual int calculateSerializeBufferSize() const;
 
        virtual const char* serialize(void* dataBuffer, btSerializer* serializer) const;
};
 
struct btConeTwistConstraintDoubleData
{
        btTypedConstraintDoubleData m_typeConstraintData;
        btTransformDoubleData m_rbAFrame;
        btTransformDoubleData m_rbBFrame;
 
        //limits
        double m_swingSpan1;
        double m_swingSpan2;
        double m_twistSpan;
        double m_limitSoftness;
        double m_biasFactor;
        double m_relaxationFactor;
 
        double m_damping;
};
 
#ifdef BT_BACKWARDS_COMPATIBLE_SERIALIZATION
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];
};
#endif  //BT_BACKWARDS_COMPATIBLE_SERIALIZATION
//
 
SIMD_FORCE_INLINE int btConeTwistConstraint::calculateSerializeBufferSize() const
{
        return sizeof(btConeTwistConstraintData2);
}
 
SIMD_FORCE_INLINE const char* btConeTwistConstraint::serialize(void* dataBuffer, btSerializer* serializer) const
{
        btConeTwistConstraintData2* cone = (btConeTwistConstraintData2*)dataBuffer;
        btTypedConstraint::serialize(&cone->m_typeConstraintData, serializer);
 
        m_rbAFrame.serialize(cone->m_rbAFrame);
        m_rbBFrame.serialize(cone->m_rbBFrame);
 
        cone->m_swingSpan1 = m_swingSpan1;
        cone->m_swingSpan2 = m_swingSpan2;
        cone->m_twistSpan = m_twistSpan;
        cone->m_limitSoftness = m_limitSoftness;
        cone->m_biasFactor = m_biasFactor;
        cone->m_relaxationFactor = m_relaxationFactor;
        cone->m_damping = m_damping;
 
        return btConeTwistConstraintDataName;
}
 
#endif  //BT_CONETWISTCONSTRAINT_H