b2_friction_joint.h

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// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#ifndef B2_FRICTION_JOINT_H
#define B2_FRICTION_JOINT_H

#include "b2_api.h"
#include "b2_joint.h"

struct B2_API b2FrictionJointDef : public b2JointDef
{
        b2FrictionJointDef()
        {
                type = e_frictionJoint;
                localAnchorA.SetZero();
                localAnchorB.SetZero();
                maxForce = 0.0f;
                maxTorque = 0.0f;
        }

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

        b2Vec2 localAnchorA;

        b2Vec2 localAnchorB;

        float maxForce;

        float maxTorque;
};

class B2_API b2FrictionJoint : public b2Joint
{
public:
        b2Vec2 GetAnchorA() const override;
        b2Vec2 GetAnchorB() const override;

        b2Vec2 GetReactionForce(float inv_dt) const override;
        float GetReactionTorque(float inv_dt) const override;

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

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

        void SetMaxForce(float force);

        float GetMaxForce() const;

        void SetMaxTorque(float torque);

        float GetMaxTorque() const;

        void Dump() override;

protected:

        friend class b2Joint;

        b2FrictionJoint(const b2FrictionJointDef* def);

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

        b2Vec2 m_localAnchorA;
        b2Vec2 m_localAnchorB;

        // Solver shared
        b2Vec2 m_linearImpulse;
        float m_angularImpulse;
        float m_maxForce;
        float m_maxTorque;

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

#endif