b2_wheel_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_WHEEL_JOINT_H
#define B2_WHEEL_JOINT_H
 
#include "b2_api.h"
#include "b2_joint.h"
 
struct B2_API b2WheelJointDef : public b2JointDef
{
        b2WheelJointDef()
        {
                type = e_wheelJoint;
                localAnchorA.SetZero();
                localAnchorB.SetZero();
                localAxisA.Set(1.0f, 0.0f);
                enableLimit = false;
                lowerTranslation = 0.0f;
                upperTranslation = 0.0f;
                enableMotor = false;
                maxMotorTorque = 0.0f;
                motorSpeed = 0.0f;
                stiffness = 0.0f;
                damping = 0.0f;
        }
 
        void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor, const b2Vec2& axis);
 
        b2Vec2 localAnchorA;
 
        b2Vec2 localAnchorB;
 
        b2Vec2 localAxisA;
 
        bool enableLimit;
 
        float lowerTranslation;
 
        float upperTranslation;
 
        bool enableMotor;
 
        float maxMotorTorque;
 
        float motorSpeed;
 
        float stiffness;
 
        float damping;
};
 
class B2_API b2WheelJoint : 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; }
 
        const b2Vec2& GetLocalAxisA() const { return m_localXAxisA; }
 
        float GetJointTranslation() const;
 
        float GetJointLinearSpeed() const;
 
        float GetJointAngle() const;
 
        float GetJointAngularSpeed() const;
 
        bool IsLimitEnabled() const;
 
        void EnableLimit(bool flag);
 
        float GetLowerLimit() const;
 
        float GetUpperLimit() const;
 
        void SetLimits(float lower, float upper);
 
        bool IsMotorEnabled() const;
 
        void EnableMotor(bool flag);
 
        void SetMotorSpeed(float speed);
 
        float GetMotorSpeed() const;
 
        void SetMaxMotorTorque(float torque);
        float GetMaxMotorTorque() const;
 
        float GetMotorTorque(float inv_dt) const;
 
        void SetStiffness(float stiffness);
        float GetStiffness() const;
 
        void SetDamping(float damping);
        float GetDamping() const;
 
        void Dump() override;
 
        void Draw(b2Draw* draw) const override;
 
protected:
 
        friend class b2Joint;
        b2WheelJoint(const b2WheelJointDef* 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;
        b2Vec2 m_localXAxisA;
        b2Vec2 m_localYAxisA;
 
        float m_impulse;
        float m_motorImpulse;
        float m_springImpulse;
 
        float m_lowerImpulse;
        float m_upperImpulse;
        float m_translation;
        float m_lowerTranslation;
        float m_upperTranslation;
 
        float m_maxMotorTorque;
        float m_motorSpeed;
 
        bool m_enableLimit;
        bool m_enableMotor;
 
        float m_stiffness;
        float m_damping;
 
        // Solver temp
        int32 m_indexA;
        int32 m_indexB;
        b2Vec2 m_localCenterA;
        b2Vec2 m_localCenterB;
        float m_invMassA;
        float m_invMassB;
        float m_invIA;
        float m_invIB;
 
        b2Vec2 m_ax, m_ay;
        float m_sAx, m_sBx;
        float m_sAy, m_sBy;
 
        float m_mass;
        float m_motorMass;
        float m_axialMass;
        float m_springMass;
 
        float m_bias;
        float m_gamma;
 
};
 
inline float b2WheelJoint::GetMotorSpeed() const
{
        return m_motorSpeed;
}
 
inline float b2WheelJoint::GetMaxMotorTorque() const
{
        return m_maxMotorTorque;
}
 
#endif