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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"
/// Friction joint definition.
struct B2_API b2FrictionJointDef : public b2JointDef
{
b2FrictionJointDef()
{
type = e_frictionJoint;
localAnchorA.SetZero();
localAnchorB.SetZero();
maxForce = 0.0f;
maxTorque = 0.0f;
}
/// Initialize the bodies, anchors, axis, and reference angle using the world
/// anchor and world axis.
void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
/// The local anchor point relative to bodyA's origin.
b2Vec2 localAnchorA;
/// The local anchor point relative to bodyB's origin.
b2Vec2 localAnchorB;
/// The maximum friction force in N.
float maxForce;
/// The maximum friction torque in N-m.
float maxTorque;
};
/// Friction joint. This is used for top-down friction.
/// It provides 2D translational friction and angular friction.
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;
/// The local anchor point relative to bodyA's origin.
const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
/// The local anchor point relative to bodyB's origin.
const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
/// 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;
/// Dump joint to dmLog
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
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