Box2D  2.2.0
A 2D Physics Engine for Games
b2GearJoint.h
00001 /*
00002 * Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
00003 *
00004 * This software is provided 'as-is', without any express or implied
00005 * warranty.  In no event will the authors be held liable for any damages
00006 * arising from the use of this software.
00007 * Permission is granted to anyone to use this software for any purpose,
00008 * including commercial applications, and to alter it and redistribute it
00009 * freely, subject to the following restrictions:
00010 * 1. The origin of this software must not be misrepresented; you must not
00011 * claim that you wrote the original software. If you use this software
00012 * in a product, an acknowledgment in the product documentation would be
00013 * appreciated but is not required.
00014 * 2. Altered source versions must be plainly marked as such, and must not be
00015 * misrepresented as being the original software.
00016 * 3. This notice may not be removed or altered from any source distribution.
00017 */
00018 
00019 #ifndef B2_GEAR_JOINT_H
00020 #define B2_GEAR_JOINT_H
00021 
00022 #include <Box2D/Dynamics/Joints/b2Joint.h>
00023 
00026 struct b2GearJointDef : public b2JointDef
00027 {
00028         b2GearJointDef()
00029         {
00030                 type = e_gearJoint;
00031                 joint1 = NULL;
00032                 joint2 = NULL;
00033                 ratio = 1.0f;
00034         }
00035 
00037         b2Joint* joint1;
00038 
00040         b2Joint* joint2;
00041 
00044         float32 ratio;
00045 };
00046 
00056 class b2GearJoint : public b2Joint
00057 {
00058 public:
00059         b2Vec2 GetAnchorA() const;
00060         b2Vec2 GetAnchorB() const;
00061 
00062         b2Vec2 GetReactionForce(float32 inv_dt) const;
00063         float32 GetReactionTorque(float32 inv_dt) const;
00064 
00066         void SetRatio(float32 ratio);
00067         float32 GetRatio() const;
00068 
00069 protected:
00070 
00071         friend class b2Joint;
00072         b2GearJoint(const b2GearJointDef* data);
00073 
00074         void InitVelocityConstraints(const b2SolverData& data);
00075         void SolveVelocityConstraints(const b2SolverData& data);
00076         bool SolvePositionConstraints(const b2SolverData& data);
00077 
00078         b2JointType m_typeA;
00079         b2JointType m_typeB;
00080 
00081         // Body A is connected to body C
00082         // Body B is connected to body D
00083         b2Body* m_bodyC;
00084         b2Body* m_bodyD;
00085 
00086         // Solver shared
00087         b2Vec2 m_localAnchorA;
00088         b2Vec2 m_localAnchorB;
00089         b2Vec2 m_localAnchorC;
00090         b2Vec2 m_localAnchorD;
00091 
00092         b2Vec2 m_localAxisC;
00093         b2Vec2 m_localAxisD;
00094 
00095         float32 m_referenceAngleA;
00096         float32 m_referenceAngleB;
00097 
00098         float32 m_constant;
00099         float32 m_ratio;
00100 
00101         float32 m_impulse;
00102 
00103         // Solver temp
00104         int32 m_indexA, m_indexB, m_indexC, m_indexD;
00105         b2Vec2 m_lcA, m_lcB, m_lcC, m_lcD;
00106         float32 m_mA, m_mB, m_mC, m_mD;
00107         float32 m_iA, m_iB, m_iC, m_iD;
00108         b2Vec2 m_JvAC, m_JvBD;
00109         float32 m_JwA, m_JwB, m_JwC, m_JwD;
00110         float32 m_mass;
00111 };
00112 
00113 #endif
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