Box2D  2.4.0
A 2D physics engine for games
b2_rope_joint.h
1 // MIT License
2 
3 // Copyright (c) 2019 Erin Catto
4 
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22 
23 #ifndef B2_ROPE_JOINT_H
24 #define B2_ROPE_JOINT_H
25 
26 #include "b2_api.h"
27 #include "b2_joint.h"
28 
33 struct B2_API b2RopeJointDef : public b2JointDef
34 {
36  {
37  type = e_ropeJoint;
38  localAnchorA.Set(-1.0f, 0.0f);
39  localAnchorB.Set(1.0f, 0.0f);
40  maxLength = 0.0f;
41  }
42 
45 
48 
52  float maxLength;
53 };
54 
63 class B2_API b2RopeJoint : public b2Joint
64 {
65 public:
66  b2Vec2 GetAnchorA() const override;
67  b2Vec2 GetAnchorB() const override;
68 
69  b2Vec2 GetReactionForce(float inv_dt) const override;
70  float GetReactionTorque(float inv_dt) const override;
71 
73  const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
74 
76  const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
77 
79  void SetMaxLength(float length) { m_maxLength = length; }
80  float GetMaxLength() const;
81 
82  // Get current length
83  float GetLength() const;
84 
86  void Dump() override;
87 
88 protected:
89 
90  friend class b2Joint;
91  b2RopeJoint(const b2RopeJointDef* data);
92 
93  void InitVelocityConstraints(const b2SolverData& data) override;
94  void SolveVelocityConstraints(const b2SolverData& data) override;
95  bool SolvePositionConstraints(const b2SolverData& data) override;
96 
97  // Solver shared
98  b2Vec2 m_localAnchorA;
99  b2Vec2 m_localAnchorB;
100  float m_maxLength;
101  float m_length;
102  float m_impulse;
103 
104  // Solver temp
105  int32 m_indexA;
106  int32 m_indexB;
107  b2Vec2 m_u;
108  b2Vec2 m_rA;
109  b2Vec2 m_rB;
110  b2Vec2 m_localCenterA;
111  b2Vec2 m_localCenterB;
112  float m_invMassA;
113  float m_invMassB;
114  float m_invIA;
115  float m_invIB;
116  float m_mass;
117 };
118 
119 #endif
b2Vec2
A 2D column vector.
Definition: b2_math.h:42
b2RopeJoint::GetReactionForce
b2Vec2 GetReactionForce(float inv_dt) const override
Get the reaction force on bodyB at the joint anchor in Newtons.
b2JointDef
Joint definitions are used to construct joints.
Definition: b2_joint.h:73
b2RopeJoint::GetLocalAnchorB
const b2Vec2 & GetLocalAnchorB() const
The local anchor point relative to bodyB's origin.
Definition: b2_rope_joint.h:76
b2RopeJoint::GetLocalAnchorA
const b2Vec2 & GetLocalAnchorA() const
The local anchor point relative to bodyA's origin.
Definition: b2_rope_joint.h:73
b2RopeJointDef::localAnchorA
b2Vec2 localAnchorA
The local anchor point relative to bodyA's origin.
Definition: b2_rope_joint.h:44
b2RopeJoint::GetAnchorB
b2Vec2 GetAnchorB() const override
Get the anchor point on bodyB in world coordinates.
b2RopeJointDef
Definition: b2_rope_joint.h:34
b2RopeJoint::SetMaxLength
void SetMaxLength(float length)
Set/Get the maximum length of the rope.
Definition: b2_rope_joint.h:79
b2SolverData
Solver Data.
Definition: b2_time_step.h:68
b2RopeJoint
Definition: b2_rope_joint.h:64
b2RopeJointDef::localAnchorB
b2Vec2 localAnchorB
The local anchor point relative to bodyB's origin.
Definition: b2_rope_joint.h:47
b2RopeJointDef::maxLength
float maxLength
Definition: b2_rope_joint.h:52
b2RopeJoint::GetAnchorA
b2Vec2 GetAnchorA() const override
Get the anchor point on bodyA in world coordinates.
b2Joint
Definition: b2_joint.h:112
b2RopeJoint::GetReactionTorque
float GetReactionTorque(float inv_dt) const override
Get the reaction torque on bodyB in N*m.
b2RopeJoint::Dump
void Dump() override
Dump joint to dmLog.