1 | /* |
2 | * Copyright (c) 2006-2007 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_FRICTION_JOINT_H |
20 | #define B2_FRICTION_JOINT_H |
21 | |
22 | #include <Box2D/Dynamics/Joints/b2Joint.h> |
23 | |
24 | /// Friction joint definition. |
25 | struct b2FrictionJointDef : public b2JointDef |
26 | { |
27 | b2FrictionJointDef() |
28 | { |
29 | type = e_frictionJoint; |
30 | localAnchorA.SetZero(); |
31 | localAnchorB.SetZero(); |
32 | maxForce = 0.0f; |
33 | maxTorque = 0.0f; |
34 | } |
35 | |
36 | /// Initialize the bodies, anchors, axis, and reference angle using the world |
37 | /// anchor and world axis. |
38 | void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor); |
39 | |
40 | /// The local anchor point relative to bodyA's origin. |
41 | b2Vec2 localAnchorA; |
42 | |
43 | /// The local anchor point relative to bodyB's origin. |
44 | b2Vec2 localAnchorB; |
45 | |
46 | /// The maximum friction force in N. |
47 | float32 maxForce; |
48 | |
49 | /// The maximum friction torque in N-m. |
50 | float32 maxTorque; |
51 | }; |
52 | |
53 | /// Friction joint. This is used for top-down friction. |
54 | /// It provides 2D translational friction and angular friction. |
55 | class b2FrictionJoint : public b2Joint |
56 | { |
57 | public: |
58 | b2Vec2 GetAnchorA() const; |
59 | b2Vec2 GetAnchorB() const; |
60 | |
61 | b2Vec2 GetReactionForce(float32 inv_dt) const; |
62 | float32 GetReactionTorque(float32 inv_dt) const; |
63 | |
64 | /// The local anchor point relative to bodyA's origin. |
65 | const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; } |
66 | |
67 | /// The local anchor point relative to bodyB's origin. |
68 | const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; } |
69 | |
70 | /// Set the maximum friction force in N. |
71 | void SetMaxForce(float32 force); |
72 | |
73 | /// Get the maximum friction force in N. |
74 | float32 GetMaxForce() const; |
75 | |
76 | /// Set the maximum friction torque in N*m. |
77 | void SetMaxTorque(float32 torque); |
78 | |
79 | /// Get the maximum friction torque in N*m. |
80 | float32 GetMaxTorque() const; |
81 | |
82 | /// Dump joint to dmLog |
83 | void Dump(); |
84 | |
85 | protected: |
86 | |
87 | friend class b2Joint; |
88 | |
89 | b2FrictionJoint(const b2FrictionJointDef* def); |
90 | |
91 | void InitVelocityConstraints(const b2SolverData& data); |
92 | void SolveVelocityConstraints(const b2SolverData& data); |
93 | bool SolvePositionConstraints(const b2SolverData& data); |
94 | |
95 | b2Vec2 m_localAnchorA; |
96 | b2Vec2 m_localAnchorB; |
97 | |
98 | // Solver shared |
99 | b2Vec2 m_linearImpulse; |
100 | float32 m_angularImpulse; |
101 | float32 m_maxForce; |
102 | float32 m_maxTorque; |
103 | |
104 | // Solver temp |
105 | int32 m_indexA; |
106 | int32 m_indexB; |
107 | b2Vec2 m_rA; |
108 | b2Vec2 m_rB; |
109 | b2Vec2 m_localCenterA; |
110 | b2Vec2 m_localCenterB; |
111 | float32 m_invMassA; |
112 | float32 m_invMassB; |
113 | float32 m_invIA; |
114 | float32 m_invIB; |
115 | b2Mat22 m_linearMass; |
116 | float32 m_angularMass; |
117 | }; |
118 | |
119 | #endif |
120 | |