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b2GearJoint.h
1 /*
2 * Copyright (c) 2006-2011 Erin Catto http://www.box2d.org
3 *
4 * This software is provided 'as-is', without any express or implied
5 * warranty. In no event will the authors be held liable for any damages
6 * arising from the use of this software.
7 * Permission is granted to anyone to use this software for any purpose,
8 * including commercial applications, and to alter it and redistribute it
9 * freely, subject to the following restrictions:
10 * 1. The origin of this software must not be misrepresented; you must not
11 * claim that you wrote the original software. If you use this software
12 * in a product, an acknowledgment in the product documentation would be
13 * appreciated but is not required.
14 * 2. Altered source versions must be plainly marked as such, and must not be
15 * misrepresented as being the original software.
16 * 3. This notice may not be removed or altered from any source distribution.
17 */
18 
19 #ifndef B2_GEAR_JOINT_H
20 #define B2_GEAR_JOINT_H
21 
22 #include <Box2D/Dynamics/Joints/b2Joint.h>
23 
26 struct b2GearJointDef : public b2JointDef
27 {
29  {
30  type = e_gearJoint;
31  joint1 = NULL;
32  joint2 = NULL;
33  ratio = 1.0f;
34  }
35 
38 
41 
44  float32 ratio;
45 };
46 
56 class b2GearJoint : public b2Joint
57 {
58 public:
59  b2Vec2 GetAnchorA() const;
60  b2Vec2 GetAnchorB() const;
61 
62  b2Vec2 GetReactionForce(float32 inv_dt) const;
63  float32 GetReactionTorque(float32 inv_dt) const;
64 
66  b2Joint* GetJoint1() { return m_joint1; }
67 
69  b2Joint* GetJoint2() { return m_joint2; }
70 
72  void SetRatio(float32 ratio);
73  float32 GetRatio() const;
74 
76  void Dump();
77 
78 protected:
79 
80  friend class b2Joint;
81  b2GearJoint(const b2GearJointDef* data);
82 
83  void InitVelocityConstraints(const b2SolverData& data);
84  void SolveVelocityConstraints(const b2SolverData& data);
85  bool SolvePositionConstraints(const b2SolverData& data);
86 
87  b2Joint* m_joint1;
88  b2Joint* m_joint2;
89 
90  b2JointType m_typeA;
91  b2JointType m_typeB;
92 
93  // Body A is connected to body C
94  // Body B is connected to body D
95  b2Body* m_bodyC;
96  b2Body* m_bodyD;
97 
98  // Solver shared
99  b2Vec2 m_localAnchorA;
100  b2Vec2 m_localAnchorB;
101  b2Vec2 m_localAnchorC;
102  b2Vec2 m_localAnchorD;
103 
104  b2Vec2 m_localAxisC;
105  b2Vec2 m_localAxisD;
106 
107  float32 m_referenceAngleA;
108  float32 m_referenceAngleB;
109 
110  float32 m_constant;
111  float32 m_ratio;
112 
113  float32 m_impulse;
114 
115  // Solver temp
116  int32 m_indexA, m_indexB, m_indexC, m_indexD;
117  b2Vec2 m_lcA, m_lcB, m_lcC, m_lcD;
118  float32 m_mA, m_mB, m_mC, m_mD;
119  float32 m_iA, m_iB, m_iC, m_iD;
120  b2Vec2 m_JvAC, m_JvBD;
121  float32 m_JwA, m_JwB, m_JwC, m_JwD;
122  float32 m_mass;
123 };
124 
125 #endif
void SetRatio(float32 ratio)
Set/Get the gear ratio.
Definition: b2GearJoint.cpp:392
b2Joint * joint1
The first revolute/prismatic joint attached to the gear joint.
Definition: b2GearJoint.h:37
b2Vec2 GetAnchorB() const
Get the anchor point on bodyB in world coordinates.
Definition: b2GearJoint.cpp:375
Definition: b2Joint.h:103
b2Vec2 GetAnchorA() const
Get the anchor point on bodyA in world coordinates.
Definition: b2GearJoint.cpp:370
b2Vec2 GetReactionForce(float32 inv_dt) const
Get the reaction force on bodyB at the joint anchor in Newtons.
Definition: b2GearJoint.cpp:380
Definition: b2GearJoint.h:56
b2Joint * joint2
The second revolute/prismatic joint attached to the gear joint.
Definition: b2GearJoint.h:40
float32 ratio
Definition: b2GearJoint.h:44
b2Joint * GetJoint1()
Get the first joint.
Definition: b2GearJoint.h:66
b2JointType type
The joint type is set automatically for concrete joint types.
Definition: b2Joint.h:86
Solver Data.
Definition: b2TimeStep.h:65
Joint definitions are used to construct joints.
Definition: b2Joint.h:74
float32 GetReactionTorque(float32 inv_dt) const
Get the reaction torque on bodyB in N*m.
Definition: b2GearJoint.cpp:386
A rigid body. These are created via b2World::CreateBody.
Definition: b2Body.h:132
void Dump()
Dump joint to dmLog.
Definition: b2GearJoint.cpp:403
A 2D column vector.
Definition: b2Math.h:56
Definition: b2GearJoint.h:26
b2Joint * GetJoint2()
Get the second joint.
Definition: b2GearJoint.h:69