Box2D  2.4.1
A 2D physics engine for games
b2_mouse_joint.h
1 // MIT License
2 
3 // Copyright (c) 2019 Erin Catto
4 
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22 
23 #ifndef B2_MOUSE_JOINT_H
24 #define B2_MOUSE_JOINT_H
25 
26 #include "b2_api.h"
27 #include "b2_joint.h"
28 
31 struct B2_API b2MouseJointDef : public b2JointDef
32 {
34  {
35  type = e_mouseJoint;
36  target.Set(0.0f, 0.0f);
37  maxForce = 0.0f;
38  stiffness = 0.0f;
39  damping = 0.0f;
40  }
41 
45 
49  float maxForce;
50 
52  float stiffness;
53 
55  float damping;
56 };
57 
65 class B2_API b2MouseJoint : public b2Joint
66 {
67 public:
68 
70  b2Vec2 GetAnchorA() const override;
71 
73  b2Vec2 GetAnchorB() const override;
74 
76  b2Vec2 GetReactionForce(float inv_dt) const override;
77 
79  float GetReactionTorque(float inv_dt) const override;
80 
82  void SetTarget(const b2Vec2& target);
83  const b2Vec2& GetTarget() const;
84 
86  void SetMaxForce(float force);
87  float GetMaxForce() const;
88 
90  void SetStiffness(float stiffness) { m_stiffness = stiffness; }
91  float GetStiffness() const { return m_stiffness; }
92 
94  void SetDamping(float damping) { m_damping = damping; }
95  float GetDamping() const { return m_damping; }
96 
98  void Dump() override { b2Log("Mouse joint dumping is not supported.\n"); }
99 
101  void ShiftOrigin(const b2Vec2& newOrigin) override;
102 
103 protected:
104  friend class b2Joint;
105 
106  b2MouseJoint(const b2MouseJointDef* def);
107 
108  void InitVelocityConstraints(const b2SolverData& data) override;
109  void SolveVelocityConstraints(const b2SolverData& data) override;
110  bool SolvePositionConstraints(const b2SolverData& data) override;
111 
112  b2Vec2 m_localAnchorB;
113  b2Vec2 m_targetA;
114  float m_stiffness;
115  float m_damping;
116  float m_beta;
117 
118  // Solver shared
119  b2Vec2 m_impulse;
120  float m_maxForce;
121  float m_gamma;
122 
123  // Solver temp
124  int32 m_indexA;
125  int32 m_indexB;
126  b2Vec2 m_rB;
127  b2Vec2 m_localCenterB;
128  float m_invMassB;
129  float m_invIB;
130  b2Mat22 m_mass;
131  b2Vec2 m_C;
132 };
133 
134 #endif
b2Vec2
A 2D column vector.
Definition: b2_math.h:41
b2Joint::GetReactionForce
virtual b2Vec2 GetReactionForce(float inv_dt) const =0
Get the reaction force on bodyB at the joint anchor in Newtons.
b2Joint::GetAnchorA
virtual b2Vec2 GetAnchorA() const =0
Get the anchor point on bodyA in world coordinates.
b2Log
void b2Log(const char *string,...)
Implement this to use your own logging.
Definition: b2_settings.h:115
b2JointDef
Joint definitions are used to construct joints.
Definition: b2_joint.h:72
b2MouseJointDef::target
b2Vec2 target
Definition: b2_mouse_joint.h:44
b2MouseJoint::SetStiffness
void SetStiffness(float stiffness)
Set/get the linear stiffness in N/m.
Definition: b2_mouse_joint.h:90
b2MouseJoint::SetDamping
void SetDamping(float damping)
Set/get linear damping in N*s/m.
Definition: b2_mouse_joint.h:94
b2MouseJoint::Dump
void Dump() override
The mouse joint does not support dumping.
Definition: b2_mouse_joint.h:98
b2Joint::ShiftOrigin
virtual void ShiftOrigin(const b2Vec2 &newOrigin)
Shift the origin for any points stored in world coordinates.
Definition: b2_joint.h:154
b2Mat22
A 2-by-2 matrix. Stored in column-major order.
Definition: b2_math.h:171
b2SolverData
Solver Data.
Definition: b2_time_step.h:67
b2Joint::GetAnchorB
virtual b2Vec2 GetAnchorB() const =0
Get the anchor point on bodyB in world coordinates.
b2MouseJointDef
Definition: b2_mouse_joint.h:31
b2MouseJoint
Definition: b2_mouse_joint.h:65
b2MouseJointDef::maxForce
float maxForce
Definition: b2_mouse_joint.h:49
b2Joint
Definition: b2_joint.h:110
b2Joint::GetReactionTorque
virtual float GetReactionTorque(float inv_dt) const =0
Get the reaction torque on bodyB in N*m.
b2MouseJointDef::damping
float damping
The linear damping in N*s/m.
Definition: b2_mouse_joint.h:55
b2MouseJointDef::stiffness
float stiffness
The linear stiffness in N/m.
Definition: b2_mouse_joint.h:52