126 lines
3.5 KiB
C
126 lines
3.5 KiB
C
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/*
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* Copyright (c) 2006-2011 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_GEAR_JOINT_H
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#define B2_GEAR_JOINT_H
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#include "Box2D/Dynamics/Joints/b2Joint.h"
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/// Gear joint definition. This definition requires two existing
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/// revolute or prismatic joints (any combination will work).
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struct b2GearJointDef : public b2JointDef
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{
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b2GearJointDef()
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{
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type = e_gearJoint;
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joint1 = nullptr;
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joint2 = nullptr;
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ratio = 1.0f;
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}
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/// The first revolute/prismatic joint attached to the gear joint.
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b2Joint* joint1;
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/// The second revolute/prismatic joint attached to the gear joint.
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b2Joint* joint2;
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/// The gear ratio.
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/// @see b2GearJoint for explanation.
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float32 ratio;
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};
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/// A gear joint is used to connect two joints together. Either joint
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/// can be a revolute or prismatic joint. You specify a gear ratio
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/// to bind the motions together:
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/// coordinate1 + ratio * coordinate2 = constant
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/// The ratio can be negative or positive. If one joint is a revolute joint
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/// and the other joint is a prismatic joint, then the ratio will have units
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/// of length or units of 1/length.
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/// @warning You have to manually destroy the gear joint if joint1 or joint2
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/// is destroyed.
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class b2GearJoint : 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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/// Get the first joint.
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b2Joint* GetJoint1() { return m_joint1; }
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/// Get the second joint.
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b2Joint* GetJoint2() { return m_joint2; }
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/// Set/Get the gear ratio.
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void SetRatio(float32 ratio);
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float32 GetRatio() 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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b2GearJoint(const b2GearJointDef* data);
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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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b2Joint* m_joint1;
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b2Joint* m_joint2;
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b2JointType m_typeA;
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b2JointType m_typeB;
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// Body A is connected to body C
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// Body B is connected to body D
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b2Body* m_bodyC;
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b2Body* m_bodyD;
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// Solver shared
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b2Vec2 m_localAnchorA;
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b2Vec2 m_localAnchorB;
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b2Vec2 m_localAnchorC;
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b2Vec2 m_localAnchorD;
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b2Vec2 m_localAxisC;
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b2Vec2 m_localAxisD;
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float32 m_referenceAngleA;
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float32 m_referenceAngleB;
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float32 m_constant;
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float32 m_ratio;
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float32 m_impulse;
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// Solver temp
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int32 m_indexA, m_indexB, m_indexC, m_indexD;
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b2Vec2 m_lcA, m_lcB, m_lcC, m_lcD;
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float32 m_mA, m_mB, m_mC, m_mD;
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float32 m_iA, m_iB, m_iC, m_iD;
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b2Vec2 m_JvAC, m_JvBD;
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float32 m_JwA, m_JwB, m_JwC, m_JwD;
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float32 m_mass;
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};
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#endif
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