120 lines
3.3 KiB
C++
120 lines
3.3 KiB
C++
/*
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* Copyright (c) 2006-2007 Erin Catto http://www.box2d.org
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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* 3. This notice may not be removed or altered from any source distribution.
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*/
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#ifndef B2_FRICTION_JOINT_H
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#define B2_FRICTION_JOINT_H
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#include "Box2D/Dynamics/Joints/b2Joint.h"
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/// Friction joint definition.
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struct b2FrictionJointDef : public b2JointDef
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{
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b2FrictionJointDef()
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{
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type = e_frictionJoint;
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localAnchorA.SetZero();
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localAnchorB.SetZero();
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maxForce = 0.0f;
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maxTorque = 0.0f;
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}
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/// Initialize the bodies, anchors, axis, and reference angle using the world
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/// anchor and world axis.
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void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
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/// The local anchor point relative to bodyA's origin.
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b2Vec2 localAnchorA;
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/// The local anchor point relative to bodyB's origin.
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b2Vec2 localAnchorB;
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/// The maximum friction force in N.
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float32 maxForce;
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/// The maximum friction torque in N-m.
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float32 maxTorque;
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};
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/// Friction joint. This is used for top-down friction.
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/// It provides 2D translational friction and angular friction.
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class b2FrictionJoint : public b2Joint
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{
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public:
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b2Vec2 GetAnchorA() const override;
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b2Vec2 GetAnchorB() const override;
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b2Vec2 GetReactionForce(float32 inv_dt) const override;
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float32 GetReactionTorque(float32 inv_dt) const override;
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/// The local anchor point relative to bodyA's origin.
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const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
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/// The local anchor point relative to bodyB's origin.
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const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
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/// Set the maximum friction force in N.
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void SetMaxForce(float32 force);
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/// Get the maximum friction force in N.
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float32 GetMaxForce() const;
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/// Set the maximum friction torque in N*m.
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void SetMaxTorque(float32 torque);
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/// Get the maximum friction torque in N*m.
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float32 GetMaxTorque() const;
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/// Dump joint to dmLog
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void Dump() override;
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protected:
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friend class b2Joint;
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b2FrictionJoint(const b2FrictionJointDef* def);
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void InitVelocityConstraints(const b2SolverData& data) override;
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void SolveVelocityConstraints(const b2SolverData& data) override;
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bool SolvePositionConstraints(const b2SolverData& data) override;
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b2Vec2 m_localAnchorA;
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b2Vec2 m_localAnchorB;
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// Solver shared
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b2Vec2 m_linearImpulse;
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float32 m_angularImpulse;
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float32 m_maxForce;
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float32 m_maxTorque;
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// Solver temp
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int32 m_indexA;
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int32 m_indexB;
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b2Vec2 m_rA;
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b2Vec2 m_rB;
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b2Vec2 m_localCenterA;
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b2Vec2 m_localCenterB;
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float32 m_invMassA;
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float32 m_invMassB;
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float32 m_invIA;
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float32 m_invIB;
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b2Mat22 m_linearMass;
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float32 m_angularMass;
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};
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#endif
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