b2MotorJoint.h

/*
* Copyright (c) 2006-2012 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_MOTOR_JOINT_H
#define B2_MOTOR_JOINT_H

#include <Box2D/Dynamics/Joints/b2Joint.h>

struct b2MotorJointDef : public b2JointDef
{
    b2MotorJointDef()
    {
        type = e_motorJoint;
        linearOffset.SetZero();
        angularOffset = 0.0f;
        maxForce = 1.0f;
        maxTorque = 1.0f;
        correctionFactor = 0.3f;
    }

    void Initialize(b2Body* bodyA, b2Body* bodyB);

    b2Vec2 linearOffset;

    float32 angularOffset;
    
    float32 maxForce;

    float32 maxTorque;

    float32 correctionFactor;
};

class b2MotorJoint : public b2Joint
{
public:
    b2Vec2 GetAnchorA() const;
    b2Vec2 GetAnchorB() const;

    b2Vec2 GetReactionForce(float32 inv_dt) const;
    float32 GetReactionTorque(float32 inv_dt) const;

    void SetLinearOffset(const b2Vec2& linearOffset);
    const b2Vec2& GetLinearOffset() const;

    void SetAngularOffset(float32 angularOffset);
    float32 GetAngularOffset() const;

    void SetMaxForce(float32 force);

    float32 GetMaxForce() const;

    void SetMaxTorque(float32 torque);

    float32 GetMaxTorque() const;

    void SetCorrectionFactor(float32 factor);

    float32 GetCorrectionFactor() const;

    void Dump();

protected:

    friend class b2Joint;

    b2MotorJoint(const b2MotorJointDef* def);

    void InitVelocityConstraints(const b2SolverData& data);
    void SolveVelocityConstraints(const b2SolverData& data);
    bool SolvePositionConstraints(const b2SolverData& data);

    // Solver shared
    b2Vec2 m_linearOffset;
    float32 m_angularOffset;
    b2Vec2 m_linearImpulse;
    float32 m_angularImpulse;
    float32 m_maxForce;
    float32 m_maxTorque;
    float32 m_correctionFactor;

    // Solver temp
    int32 m_indexA;
    int32 m_indexB;
    b2Vec2 m_rA;
    b2Vec2 m_rB;
    b2Vec2 m_localCenterA;
    b2Vec2 m_localCenterB;
    b2Vec2 m_linearError;
    float32 m_angularError;
    float32 m_invMassA;
    float32 m_invMassB;
    float32 m_invIA;
    float32 m_invIB;
    b2Mat22 m_linearMass;
    float32 m_angularMass;
};

#endif