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/*
* Copyright (c) 2006-2007 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
#ifndef B2_FRICTION_JOINT_H
#define B2_FRICTION_JOINT_H
#include "Box2D/Dynamics/Joints/b2Joint.h"
/// Friction joint definition.
struct 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.
float32 maxForce;
/// The maximum friction torque in N-m.
float32 maxTorque;
};
/// Friction joint. This is used for top-down friction.
/// It provides 2D translational friction and angular friction.
class b2FrictionJoint : public b2Joint
{
public:
b2Vec2 GetAnchorA() const override;
b2Vec2 GetAnchorB() const override;
b2Vec2 GetReactionForce(float32 inv_dt) const override;
float32 GetReactionTorque(float32 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(float32 force);
/// Get the maximum friction force in N.
float32 GetMaxForce() const;
/// Set the maximum friction torque in N*m.
void SetMaxTorque(float32 torque);
/// Get the maximum friction torque in N*m.
float32 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;
float32 m_angularImpulse;
float32 m_maxForce;
float32 m_maxTorque;
// Solver temp
int32 m_indexA;
int32 m_indexB;
b2Vec2 m_rA;
b2Vec2 m_rB;
b2Vec2 m_localCenterA;
b2Vec2 m_localCenterB;
float32 m_invMassA;
float32 m_invMassB;
float32 m_invIA;
float32 m_invIB;
b2Mat22 m_linearMass;
float32 m_angularMass;
};
#endif
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