Box2D  2.3.0
A 2D Physics Engine for Games
b2MotorJoint.h
1 /*
2 * Copyright (c) 2006-2012 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_MOTOR_JOINT_H
20 #define B2_MOTOR_JOINT_H
21 
22 #include <Box2D/Dynamics/Joints/b2Joint.h>
23 
25 struct b2MotorJointDef : public b2JointDef
26 {
27  b2MotorJointDef()
28  {
29  type = e_motorJoint;
30  linearOffset.SetZero();
31  angularOffset = 0.0f;
32  maxForce = 1.0f;
33  maxTorque = 1.0f;
34  correctionFactor = 0.3f;
35  }
36 
38  void Initialize(b2Body* bodyA, b2Body* bodyB);
39 
41  b2Vec2 linearOffset;
42 
44  float32 angularOffset;
45 
47  float32 maxForce;
48 
50  float32 maxTorque;
51 
53  float32 correctionFactor;
54 };
55 
59 class b2MotorJoint : public b2Joint
60 {
61 public:
62  b2Vec2 GetAnchorA() const;
63  b2Vec2 GetAnchorB() const;
64 
65  b2Vec2 GetReactionForce(float32 inv_dt) const;
66  float32 GetReactionTorque(float32 inv_dt) const;
67 
69  void SetLinearOffset(const b2Vec2& linearOffset);
70  const b2Vec2& GetLinearOffset() const;
71 
73  void SetAngularOffset(float32 angularOffset);
74  float32 GetAngularOffset() const;
75 
77  void SetMaxForce(float32 force);
78 
80  float32 GetMaxForce() const;
81 
83  void SetMaxTorque(float32 torque);
84 
86  float32 GetMaxTorque() const;
87 
89  void SetCorrectionFactor(float32 factor);
90 
92  float32 GetCorrectionFactor() const;
93 
95  void Dump();
96 
97 protected:
98 
99  friend class b2Joint;
100 
101  b2MotorJoint(const b2MotorJointDef* def);
102 
103  void InitVelocityConstraints(const b2SolverData& data);
104  void SolveVelocityConstraints(const b2SolverData& data);
105  bool SolvePositionConstraints(const b2SolverData& data);
106 
107  // Solver shared
108  b2Vec2 m_linearOffset;
109  float32 m_angularOffset;
110  b2Vec2 m_linearImpulse;
111  float32 m_angularImpulse;
112  float32 m_maxForce;
113  float32 m_maxTorque;
114  float32 m_correctionFactor;
115 
116  // Solver temp
117  int32 m_indexA;
118  int32 m_indexB;
119  b2Vec2 m_rA;
120  b2Vec2 m_rB;
121  b2Vec2 m_localCenterA;
122  b2Vec2 m_localCenterB;
123  b2Vec2 m_linearError;
124  float32 m_angularError;
125  float32 m_invMassA;
126  float32 m_invMassB;
127  float32 m_invIA;
128  float32 m_invIB;
129  b2Mat22 m_linearMass;
130  float32 m_angularMass;
131 };
132 
133 #endif
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