File indexing completed on 2024-12-29 03:29:27

 /*
 * Copyright (c) 2006-2011 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_GEAR_JOINT_H
 #define B2_GEAR_JOINT_H
 
 #include <Box2D/Dynamics/Joints/b2Joint.h>
 
 /// Gear joint definition. This definition requires two existing
 /// revolute or prismatic joints (any combination will work).
 struct b2GearJointDef : public b2JointDef
 {
     b2GearJointDef()
     {
         type = e_gearJoint;
         joint1 = NULL;
         joint2 = NULL;
         ratio = 1.0f;
     }
 
     /// The first revolute/prismatic joint attached to the gear joint.
     b2Joint* joint1;
 
     /// The second revolute/prismatic joint attached to the gear joint.
     b2Joint* joint2;
 
     /// The gear ratio.
     /// @see b2GearJoint for explanation.
     float32 ratio;
 };
 
 /// A gear joint is used to connect two joints together. Either joint
 /// can be a revolute or prismatic joint. You specify a gear ratio
 /// to bind the motions together:
 /// coordinate1 + ratio * coordinate2 = constant
 /// The ratio can be negative or positive. If one joint is a revolute joint
 /// and the other joint is a prismatic joint, then the ratio will have units
 /// of length or units of 1/length.
 /// @warning You have to manually destroy the gear joint if joint1 or joint2
 /// is destroyed.
 class b2GearJoint : public b2Joint
 {
 public:
     b2Vec2 GetAnchorA() const;
     b2Vec2 GetAnchorB() const;
 
     b2Vec2 GetReactionForce(float32 inv_dt) const;
     float32 GetReactionTorque(float32 inv_dt) const;
 
     /// Get the first joint.
     b2Joint* GetJoint1() { return m_joint1; }
 
     /// Get the second joint.
     b2Joint* GetJoint2() { return m_joint2; }
 
     /// Set/Get the gear ratio.
     void SetRatio(float32 ratio);
     float32 GetRatio() const;
 
     /// Dump joint to dmLog
     void Dump();
 
 protected:
 
     friend class b2Joint;
     b2GearJoint(const b2GearJointDef* data);
 
     void InitVelocityConstraints(const b2SolverData& data);
     void SolveVelocityConstraints(const b2SolverData& data);
     bool SolvePositionConstraints(const b2SolverData& data);
 
     b2Joint* m_joint1;
     b2Joint* m_joint2;
 
     b2JointType m_typeA;
     b2JointType m_typeB;
 
     // Body A is connected to body C
     // Body B is connected to body D
     b2Body* m_bodyC;
     b2Body* m_bodyD;
 
     // Solver shared
     b2Vec2 m_localAnchorA;
     b2Vec2 m_localAnchorB;
     b2Vec2 m_localAnchorC;
     b2Vec2 m_localAnchorD;
 
     b2Vec2 m_localAxisC;
     b2Vec2 m_localAxisD;
 
     float32 m_referenceAngleA;
     float32 m_referenceAngleB;
 
     float32 m_constant;
     float32 m_ratio;
 
     float32 m_impulse;
 
     // Solver temp
     int32 m_indexA, m_indexB, m_indexC, m_indexD;
     b2Vec2 m_lcA, m_lcB, m_lcC, m_lcD;
     float32 m_mA, m_mB, m_mC, m_mD;
     float32 m_iA, m_iB, m_iC, m_iD;
     b2Vec2 m_JvAC, m_JvBD;
     float32 m_JwA, m_JwB, m_JwC, m_JwD;
     float32 m_mass;
 };
 
 #endif