Box2D  2.2.0
A 2D Physics Engine for Games
b2DistanceJoint.h
00001 /*
00002 * Copyright (c) 2006-2007 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_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 
00075         b2Vec2 GetReactionForce(float32 inv_dt) const;
00076 
00079         float32 GetReactionTorque(float32 inv_dt) const;
00080 
00083         void SetLength(float32 length);
00084         float32 GetLength() const;
00085 
00086         // Set/get frequency in Hz.
00087         void SetFrequency(float32 hz);
00088         float32 GetFrequency() const;
00089 
00090         // Set/get damping ratio.
00091         void SetDampingRatio(float32 ratio);
00092         float32 GetDampingRatio() const;
00093 
00094 protected:
00095 
00096         friend class b2Joint;
00097         b2DistanceJoint(const b2DistanceJointDef* data);
00098 
00099         void InitVelocityConstraints(const b2SolverData& data);
00100         void SolveVelocityConstraints(const b2SolverData& data);
00101         bool SolvePositionConstraints(const b2SolverData& data);
00102 
00103         float32 m_frequencyHz;
00104         float32 m_dampingRatio;
00105         float32 m_bias;
00106 
00107         // Solver shared
00108         b2Vec2 m_localAnchorA;
00109         b2Vec2 m_localAnchorB;
00110         float32 m_gamma;
00111         float32 m_impulse;
00112         float32 m_length;
00113 
00114         // Solver temp
00115         int32 m_indexA;
00116         int32 m_indexB;
00117         b2Vec2 m_u;
00118         b2Vec2 m_rA;
00119         b2Vec2 m_rB;
00120         b2Vec2 m_localCenterA;
00121         b2Vec2 m_localCenterB;
00122         float32 m_invMassA;
00123         float32 m_invMassB;
00124         float32 m_invIA;
00125         float32 m_invIB;
00126         float32 m_mass;
00127 };
00128 
00129 inline void b2DistanceJoint::SetLength(float32 length)
00130 {
00131         m_length = length;
00132 }
00133 
00134 inline float32 b2DistanceJoint::GetLength() const
00135 {
00136         return m_length;
00137 }
00138 
00139 inline void b2DistanceJoint::SetFrequency(float32 hz)
00140 {
00141         m_frequencyHz = hz;
00142 }
00143 
00144 inline float32 b2DistanceJoint::GetFrequency() const
00145 {
00146         return m_frequencyHz;
00147 }
00148 
00149 inline void b2DistanceJoint::SetDampingRatio(float32 ratio)
00150 {
00151         m_dampingRatio = ratio;
00152 }
00153 
00154 inline float32 b2DistanceJoint::GetDampingRatio() const
00155 {
00156         return m_dampingRatio;
00157 }
00158 
00159 #endif
 All Classes Files Functions Variables Enumerations Enumerator Defines