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_DISTANCE_JOINT_H 00020 #define B2_DISTANCE_JOINT_H 00021 00022 #include <Box2D/Dynamics/Joints/b2Joint.h> 00023 00030 struct b2DistanceJointDef : public b2JointDef 00031 { 00032 b2DistanceJointDef() 00033 { 00034 type = e_distanceJoint; 00035 localAnchorA.Set(0.0f, 0.0f); 00036 localAnchorB.Set(0.0f, 0.0f); 00037 length = 1.0f; 00038 frequencyHz = 0.0f; 00039 dampingRatio = 0.0f; 00040 } 00041 00044 void Initialize(b2Body* bodyA, b2Body* bodyB, 00045 const b2Vec2& anchorA, const b2Vec2& anchorB); 00046 00048 b2Vec2 localAnchorA; 00049 00051 b2Vec2 localAnchorB; 00052 00054 float32 length; 00055 00057 float32 frequencyHz; 00058 00060 float32 dampingRatio; 00061 }; 00062 00066 class b2DistanceJoint : public b2Joint 00067 { 00068 public: 00069 00070 b2Vec2 GetAnchorA() const; 00071 b2Vec2 GetAnchorB() const; 00072 00073 b2Vec2 GetReactionForce(float32 inv_dt) const; 00074 float32 GetReactionTorque(float32 inv_dt) const; 00075 00078 void SetLength(float32 length); 00079 float32 GetLength() const; 00080 00081 // Set/get frequency in Hz. 00082 void SetFrequency(float32 hz); 00083 float32 GetFrequency() const; 00084 00085 // Set/get damping ratio. 00086 void SetDampingRatio(float32 ratio); 00087 float32 GetDampingRatio() const; 00088 00089 protected: 00090 00091 friend class b2Joint; 00092 b2DistanceJoint(const b2DistanceJointDef* data); 00093 00094 void InitVelocityConstraints(const b2TimeStep& step); 00095 void SolveVelocityConstraints(const b2TimeStep& step); 00096 bool SolvePositionConstraints(float32 baumgarte); 00097 00098 b2Vec2 m_localAnchor1; 00099 b2Vec2 m_localAnchor2; 00100 b2Vec2 m_u; 00101 float32 m_frequencyHz; 00102 float32 m_dampingRatio; 00103 float32 m_gamma; 00104 float32 m_bias; 00105 float32 m_impulse; 00106 float32 m_mass; 00107 float32 m_length; 00108 }; 00109 00110 inline void b2DistanceJoint::SetLength(float32 length) 00111 { 00112 m_length = length; 00113 } 00114 00115 inline float32 b2DistanceJoint::GetLength() const 00116 { 00117 return m_length; 00118 } 00119 00120 inline void b2DistanceJoint::SetFrequency(float32 hz) 00121 { 00122 m_frequencyHz = hz; 00123 } 00124 00125 inline float32 b2DistanceJoint::GetFrequency() const 00126 { 00127 return m_frequencyHz; 00128 } 00129 00130 inline void b2DistanceJoint::SetDampingRatio(float32 ratio) 00131 { 00132 m_dampingRatio = ratio; 00133 } 00134 00135 inline float32 b2DistanceJoint::GetDampingRatio() const 00136 { 00137 return m_dampingRatio; 00138 } 00139 00140 #endif