b2RevoluteJoint.h

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/*
* Copyright (c) 2006-2011 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_REVOLUTE_JOINT_H
#define B2_REVOLUTE_JOINT_H

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

struct b2RevoluteJointDef : public b2JointDef
{
        b2RevoluteJointDef()
        {
                type = e_revoluteJoint;
                localAnchorA.Set(0.0f, 0.0f);
                localAnchorB.Set(0.0f, 0.0f);
                referenceAngle = 0.0f;
                lowerAngle = 0.0f;
                upperAngle = 0.0f;
                maxMotorTorque = 0.0f;
                motorSpeed = 0.0f;
                enableLimit = false;
                enableMotor = false;
        }

        void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);

        b2Vec2 localAnchorA;

        b2Vec2 localAnchorB;

        float32 referenceAngle;

        bool enableLimit;

        float32 lowerAngle;

        float32 upperAngle;

        bool enableMotor;

        float32 motorSpeed;

        float32 maxMotorTorque;
};

class b2RevoluteJoint : public b2Joint
{
public:
        b2Vec2 GetAnchorA() const;
        b2Vec2 GetAnchorB() const;

        const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }

        const b2Vec2& GetLocalAnchorB() const  { return m_localAnchorB; }

        float32 GetReferenceAngle() const { return m_referenceAngle; }

        float32 GetJointAngle() const;

        float32 GetJointSpeed() const;

        bool IsLimitEnabled() const;

        void EnableLimit(bool flag);

        float32 GetLowerLimit() const;

        float32 GetUpperLimit() const;

        void SetLimits(float32 lower, float32 upper);

        bool IsMotorEnabled() const;

        void EnableMotor(bool flag);

        void SetMotorSpeed(float32 speed);

        float32 GetMotorSpeed() const;

        void SetMaxMotorTorque(float32 torque);
        float32 GetMaxMotorTorque() const { return m_maxMotorTorque; }

        b2Vec2 GetReactionForce(float32 inv_dt) const;

        float32 GetReactionTorque(float32 inv_dt) const;

        float32 GetMotorTorque(float32 inv_dt) const;

        void Dump();

protected:
        
        friend class b2Joint;
        friend class b2GearJoint;

        b2RevoluteJoint(const b2RevoluteJointDef* def);

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

        // Solver shared
        b2Vec2 m_localAnchorA;
        b2Vec2 m_localAnchorB;
        b2Vec3 m_impulse;
        float32 m_motorImpulse;

        bool m_enableMotor;
        float32 m_maxMotorTorque;
        float32 m_motorSpeed;

        bool m_enableLimit;
        float32 m_referenceAngle;
        float32 m_lowerAngle;
        float32 m_upperAngle;

        // Solver temp
        int32 m_indexA;
        int32 m_indexB;
        b2Vec2 m_rA;
        b2Vec2 m_rB;
        b2Vec2 m_localCenterA;
        b2Vec2 m_localCenterB;
        float32 m_invMassA;
        float32 m_invMassB;
        float32 m_invIA;
        float32 m_invIB;
        b2Mat33 m_mass;                 // effective mass for point-to-point constraint.
        float32 m_motorMass;    // effective mass for motor/limit angular constraint.
        b2LimitState m_limitState;
};

inline float32 b2RevoluteJoint::GetMotorSpeed() const
{
        return m_motorSpeed;
}

#endif