Box2D  2.4.1
A 2D physics engine for games
b2_prismatic_joint.h
1 // MIT License
2 
3 // Copyright (c) 2019 Erin Catto
4 
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21 // SOFTWARE.
22 
23 #ifndef B2_PRISMATIC_JOINT_H
24 #define B2_PRISMATIC_JOINT_H
25 
26 #include "b2_api.h"
27 #include "b2_joint.h"
28 
35 struct B2_API b2PrismaticJointDef : public b2JointDef
36 {
38  {
39  type = e_prismaticJoint;
40  localAnchorA.SetZero();
41  localAnchorB.SetZero();
42  localAxisA.Set(1.0f, 0.0f);
43  referenceAngle = 0.0f;
44  enableLimit = false;
45  lowerTranslation = 0.0f;
46  upperTranslation = 0.0f;
47  enableMotor = false;
48  maxMotorForce = 0.0f;
49  motorSpeed = 0.0f;
50  }
51 
54  void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor, const b2Vec2& axis);
55 
58 
61 
64 
67 
70 
73 
76 
79 
82 
84  float motorSpeed;
85 };
86 
91 class B2_API b2PrismaticJoint : public b2Joint
92 {
93 public:
94  b2Vec2 GetAnchorA() const override;
95  b2Vec2 GetAnchorB() const override;
96 
97  b2Vec2 GetReactionForce(float inv_dt) const override;
98  float GetReactionTorque(float inv_dt) const override;
99 
101  const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
102 
104  const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
105 
107  const b2Vec2& GetLocalAxisA() const { return m_localXAxisA; }
108 
110  float GetReferenceAngle() const { return m_referenceAngle; }
111 
113  float GetJointTranslation() const;
114 
116  float GetJointSpeed() const;
117 
119  bool IsLimitEnabled() const;
120 
122  void EnableLimit(bool flag);
123 
125  float GetLowerLimit() const;
126 
128  float GetUpperLimit() const;
129 
131  void SetLimits(float lower, float upper);
132 
134  bool IsMotorEnabled() const;
135 
137  void EnableMotor(bool flag);
138 
140  void SetMotorSpeed(float speed);
141 
143  float GetMotorSpeed() const;
144 
146  void SetMaxMotorForce(float force);
147  float GetMaxMotorForce() const { return m_maxMotorForce; }
148 
150  float GetMotorForce(float inv_dt) const;
151 
153  void Dump() override;
154 
156  void Draw(b2Draw* draw) const override;
157 
158 protected:
159  friend class b2Joint;
160  friend class b2GearJoint;
162 
163  void InitVelocityConstraints(const b2SolverData& data) override;
164  void SolveVelocityConstraints(const b2SolverData& data) override;
165  bool SolvePositionConstraints(const b2SolverData& data) override;
166 
167  b2Vec2 m_localAnchorA;
168  b2Vec2 m_localAnchorB;
169  b2Vec2 m_localXAxisA;
170  b2Vec2 m_localYAxisA;
171  float m_referenceAngle;
172  b2Vec2 m_impulse;
173  float m_motorImpulse;
174  float m_lowerImpulse;
175  float m_upperImpulse;
176  float m_lowerTranslation;
177  float m_upperTranslation;
178  float m_maxMotorForce;
179  float m_motorSpeed;
180  bool m_enableLimit;
181  bool m_enableMotor;
182 
183  // Solver temp
184  int32 m_indexA;
185  int32 m_indexB;
186  b2Vec2 m_localCenterA;
187  b2Vec2 m_localCenterB;
188  float m_invMassA;
189  float m_invMassB;
190  float m_invIA;
191  float m_invIB;
192  b2Vec2 m_axis, m_perp;
193  float m_s1, m_s2;
194  float m_a1, m_a2;
195  b2Mat22 m_K;
196  float m_translation;
197  float m_axialMass;
198 };
199 
201 {
202  return m_motorSpeed;
203 }
204 
205 #endif
A rigid body. These are created via b2World::CreateBody.
Definition: b2_body.h:129
Definition: b2_draw.h:49
Definition: b2_gear_joint.h:62
Definition: b2_joint.h:111
Definition: b2_prismatic_joint.h:92
bool IsMotorEnabled() const
Is the joint motor enabled?
const b2Vec2 & GetLocalAnchorA() const
The local anchor point relative to bodyA's origin.
Definition: b2_prismatic_joint.h:101
float GetReactionTorque(float inv_dt) const override
Get the reaction torque on bodyB in N*m.
float GetMotorSpeed() const
Get the motor speed, usually in meters per second.
Definition: b2_prismatic_joint.h:200
void SetLimits(float lower, float upper)
Set the joint limits, usually in meters.
b2Vec2 GetReactionForce(float inv_dt) const override
Get the reaction force on bodyB at the joint anchor in Newtons.
bool IsLimitEnabled() const
Is the joint limit enabled?
float GetReferenceAngle() const
Get the reference angle.
Definition: b2_prismatic_joint.h:110
void Draw(b2Draw *draw) const override
Debug draw this joint.
void EnableMotor(bool flag)
Enable/disable the joint motor.
const b2Vec2 & GetLocalAxisA() const
The local joint axis relative to bodyA.
Definition: b2_prismatic_joint.h:107
void EnableLimit(bool flag)
Enable/disable the joint limit.
float GetUpperLimit() const
Get the upper joint limit, usually in meters.
float GetMotorForce(float inv_dt) const
Get the current motor force given the inverse time step, usually in N.
b2Vec2 GetAnchorB() const override
Get the anchor point on bodyB in world coordinates.
void Dump() override
Dump to b2Log.
float GetJointSpeed() const
Get the current joint translation speed, usually in meters per second.
void SetMaxMotorForce(float force)
Set the maximum motor force, usually in N.
void SetMotorSpeed(float speed)
Set the motor speed, usually in meters per second.
float GetLowerLimit() const
Get the lower joint limit, usually in meters.
const b2Vec2 & GetLocalAnchorB() const
The local anchor point relative to bodyB's origin.
Definition: b2_prismatic_joint.h:104
b2Vec2 GetAnchorA() const override
Get the anchor point on bodyA in world coordinates.
float GetJointTranslation() const
Get the current joint translation, usually in meters.
Joint definitions are used to construct joints.
Definition: b2_joint.h:73
A 2-by-2 matrix. Stored in column-major order.
Definition: b2_math.h:172
Definition: b2_prismatic_joint.h:36
float lowerTranslation
The lower translation limit, usually in meters.
Definition: b2_prismatic_joint.h:72
bool enableMotor
Enable/disable the joint motor.
Definition: b2_prismatic_joint.h:78
float motorSpeed
The desired motor speed in radians per second.
Definition: b2_prismatic_joint.h:84
b2Vec2 localAnchorB
The local anchor point relative to bodyB's origin.
Definition: b2_prismatic_joint.h:60
float upperTranslation
The upper translation limit, usually in meters.
Definition: b2_prismatic_joint.h:75
bool enableLimit
Enable/disable the joint limit.
Definition: b2_prismatic_joint.h:69
b2Vec2 localAnchorA
The local anchor point relative to bodyA's origin.
Definition: b2_prismatic_joint.h:57
float referenceAngle
The constrained angle between the bodies: bodyB_angle - bodyA_angle.
Definition: b2_prismatic_joint.h:66
void Initialize(b2Body *bodyA, b2Body *bodyB, const b2Vec2 &anchor, const b2Vec2 &axis)
b2Vec2 localAxisA
The local translation unit axis in bodyA.
Definition: b2_prismatic_joint.h:63
float maxMotorForce
The maximum motor torque, usually in N-m.
Definition: b2_prismatic_joint.h:81
Solver Data.
Definition: b2_time_step.h:68
A 2D column vector.
Definition: b2_math.h:42