00001 /* 00002 * Copyright (c) 2006-2007 Erin Catto http://www.gphysics.com 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 00024 class b2RevoluteJoint; 00025 class b2PrismaticJoint; 00026 00030 struct b2GearJointDef : public b2JointDef 00031 { 00032 b2GearJointDef() 00033 { 00034 type = e_gearJoint; 00035 joint1 = NULL; 00036 joint2 = NULL; 00037 ratio = 1.0f; 00038 } 00039 00041 b2Joint* joint1; 00042 00044 b2Joint* joint2; 00045 00048 float32 ratio; 00049 }; 00050 00060 class b2GearJoint : public b2Joint 00061 { 00062 public: 00063 b2Vec2 GetAnchorA() const; 00064 b2Vec2 GetAnchorB() const; 00065 00066 b2Vec2 GetReactionForce(float32 inv_dt) const; 00067 float32 GetReactionTorque(float32 inv_dt) const; 00068 00070 void SetRatio(float32 ratio); 00071 float32 GetRatio() const; 00072 00073 protected: 00074 00075 friend class b2Joint; 00076 b2GearJoint(const b2GearJointDef* data); 00077 00078 void InitVelocityConstraints(const b2TimeStep& step); 00079 void SolveVelocityConstraints(const b2TimeStep& step); 00080 bool SolvePositionConstraints(float32 baumgarte); 00081 00082 b2Body* m_ground1; 00083 b2Body* m_ground2; 00084 00085 // One of these is NULL. 00086 b2RevoluteJoint* m_revolute1; 00087 b2PrismaticJoint* m_prismatic1; 00088 00089 // One of these is NULL. 00090 b2RevoluteJoint* m_revolute2; 00091 b2PrismaticJoint* m_prismatic2; 00092 00093 b2Vec2 m_groundAnchor1; 00094 b2Vec2 m_groundAnchor2; 00095 00096 b2Vec2 m_localAnchor1; 00097 b2Vec2 m_localAnchor2; 00098 00099 b2Jacobian m_J; 00100 00101 float32 m_constant; 00102 float32 m_ratio; 00103 00104 // Effective mass 00105 float32 m_mass; 00106 00107 // Impulse for accumulation/warm starting. 00108 float32 m_impulse; 00109 }; 00110 00111 #endif