b2_pulley_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_PULLEY_JOINT_H
#define B2_PULLEY_JOINT_H
 
#include "b2_api.h"
#include "b2_joint.h"
 
const float b2_minPulleyLength = 2.0f;
 
struct B2_API b2PulleyJointDef : public b2JointDef
{
    b2PulleyJointDef()
    {
        type = e_pulleyJoint;
        groundAnchorA.Set(-1.0f, 1.0f);
        groundAnchorB.Set(1.0f, 1.0f);
        localAnchorA.Set(-1.0f, 0.0f);
        localAnchorB.Set(1.0f, 0.0f);
        lengthA = 0.0f;
        lengthB = 0.0f;
        ratio = 1.0f;
        collideConnected = true;
    }
 
    void Initialize(b2Body* bodyA, b2Body* bodyB,
                    const b2Vec2& groundAnchorA, const b2Vec2& groundAnchorB,
                    const b2Vec2& anchorA, const b2Vec2& anchorB,
                    float ratio);
 
    b2Vec2 groundAnchorA;
 
    b2Vec2 groundAnchorB;
 
    b2Vec2 localAnchorA;
 
    b2Vec2 localAnchorB;
 
    float lengthA;
 
    float lengthB;
 
    float ratio;
};
 
class B2_API b2PulleyJoint : 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;
 
    b2Vec2 GetGroundAnchorA() const;
 
    b2Vec2 GetGroundAnchorB() const;
 
    float GetLengthA() const;
 
    float GetLengthB() const;
 
    float GetRatio() const;
 
    float GetCurrentLengthA() const;
 
    float GetCurrentLengthB() const;
 
    void Dump() override;
 
    void ShiftOrigin(const b2Vec2& newOrigin) override;
 
protected:
 
    friend class b2Joint;
    b2PulleyJoint(const b2PulleyJointDef* data);
 
    void InitVelocityConstraints(const b2SolverData& data) override;
    void SolveVelocityConstraints(const b2SolverData& data) override;
    bool SolvePositionConstraints(const b2SolverData& data) override;
 
    b2Vec2 m_groundAnchorA;
    b2Vec2 m_groundAnchorB;
    float m_lengthA;
    float m_lengthB;
 
    // Solver shared
    b2Vec2 m_localAnchorA;
    b2Vec2 m_localAnchorB;
    float m_constant;
    float m_ratio;
    float m_impulse;
 
    // Solver temp
    int32 m_indexA;
    int32 m_indexB;
    b2Vec2 m_uA;
    b2Vec2 m_uB;
    b2Vec2 m_rA;
    b2Vec2 m_rB;
    b2Vec2 m_localCenterA;
    b2Vec2 m_localCenterB;
    float m_invMassA;
    float m_invMassB;
    float m_invIA;
    float m_invIB;
    float m_mass;
};
 
#endif