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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_MOTOR_JOINT_H
#define B2_MOTOR_JOINT_H
#include "b2_api.h"
#include "b2_joint.h"
/// Motor joint definition.
struct B2_API b2MotorJointDef : public b2JointDef
{
b2MotorJointDef()
{
type = e_motorJoint;
linearOffset.SetZero();
angularOffset = 0.0f;
maxForce = 1.0f;
maxTorque = 1.0f;
correctionFactor = 0.3f;
}
/// Initialize the bodies and offsets using the current transforms.
void Initialize(b2Body* bodyA, b2Body* bodyB);
/// Position of bodyB minus the position of bodyA, in bodyA's frame, in meters.
b2Vec2 linearOffset;
/// The bodyB angle minus bodyA angle in radians.
float angularOffset;
/// The maximum motor force in N.
float maxForce;
/// The maximum motor torque in N-m.
float maxTorque;
/// Position correction factor in the range [0,1].
float correctionFactor;
};
/// A motor joint is used to control the relative motion
/// between two bodies. A typical usage is to control the movement
/// of a dynamic body with respect to the ground.
class B2_API b2MotorJoint : 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;
/// Set/get the target linear offset, in frame A, in meters.
void SetLinearOffset(const b2Vec2& linearOffset);
const b2Vec2& GetLinearOffset() const;
/// Set/get the target angular offset, in radians.
void SetAngularOffset(float angularOffset);
float GetAngularOffset() const;
/// Set the maximum friction force in N.
void SetMaxForce(float force);
/// Get the maximum friction force in N.
float GetMaxForce() const;
/// Set the maximum friction torque in N*m.
void SetMaxTorque(float torque);
/// Get the maximum friction torque in N*m.
float GetMaxTorque() const;
/// Set the position correction factor in the range [0,1].
void SetCorrectionFactor(float factor);
/// Get the position correction factor in the range [0,1].
float GetCorrectionFactor() const;
/// Dump to b2Log
void Dump() override;
protected:
friend class b2Joint;
b2MotorJoint(const b2MotorJointDef* def);
void InitVelocityConstraints(const b2SolverData& data) override;
void SolveVelocityConstraints(const b2SolverData& data) override;
bool SolvePositionConstraints(const b2SolverData& data) override;
// Solver shared
b2Vec2 m_linearOffset;
float m_angularOffset;
b2Vec2 m_linearImpulse;
float m_angularImpulse;
float m_maxForce;
float m_maxTorque;
float m_correctionFactor;
// Solver temp
int32 m_indexA;
int32 m_indexB;
b2Vec2 m_rA;
b2Vec2 m_rB;
b2Vec2 m_localCenterA;
b2Vec2 m_localCenterB;
b2Vec2 m_linearError;
float m_angularError;
float m_invMassA;
float m_invMassB;
float m_invIA;
float m_invIB;
b2Mat22 m_linearMass;
float m_angularMass;
};
#endif
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