b2_gear_joint.h

// 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_GEAR_JOINT_H
#define B2_GEAR_JOINT_H
 
#include "b2_joint.h"
 
struct B2_API b2GearJointDef : public b2JointDef
{
    b2GearJointDef()
    {
        type = e_gearJoint;
        joint1 = nullptr;
        joint2 = nullptr;
        ratio = 1.0f;
    }
 
    b2Joint* joint1;
 
    b2Joint* joint2;
 
    float ratio;
};
 
class B2_API b2GearJoint : 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;
 
    b2Joint* GetJoint1() { return m_joint1; }
 
    b2Joint* GetJoint2() { return m_joint2; }
 
    void SetRatio(float ratio);
    float GetRatio() const;
 
    void Dump() override;
 
protected:
 
    friend class b2Joint;
    b2GearJoint(const b2GearJointDef* data);
 
    void InitVelocityConstraints(const b2SolverData& data) override;
    void SolveVelocityConstraints(const b2SolverData& data) override;
    bool SolvePositionConstraints(const b2SolverData& data) override;
 
    b2Joint* m_joint1;
    b2Joint* m_joint2;
 
    b2JointType m_typeA;
    b2JointType m_typeB;
 
    // Body A is connected to body C
    // Body B is connected to body D
    b2Body* m_bodyC;
    b2Body* m_bodyD;
 
    // Solver shared
    b2Vec2 m_localAnchorA;
    b2Vec2 m_localAnchorB;
    b2Vec2 m_localAnchorC;
    b2Vec2 m_localAnchorD;
 
    b2Vec2 m_localAxisC;
    b2Vec2 m_localAxisD;
 
    float m_referenceAngleA;
    float m_referenceAngleB;
 
    float m_constant;
    float m_ratio;
 
    float m_impulse;
 
    // Solver temp
    int32 m_indexA, m_indexB, m_indexC, m_indexD;
    b2Vec2 m_lcA, m_lcB, m_lcC, m_lcD;
    float m_mA, m_mB, m_mC, m_mD;
    float m_iA, m_iB, m_iC, m_iD;
    b2Vec2 m_JvAC, m_JvBD;
    float m_JwA, m_JwB, m_JwC, m_JwD;
    float m_mass;
};
 
#endif