Box2D  2.3.0
A 2D Physics Engine for Games
b2RevoluteJoint.h
1 /*
2 * Copyright (c) 2006-2011 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.
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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_REVOLUTE_JOINT_H
20 #define B2_REVOLUTE_JOINT_H
21 
22 #include <Box2D/Dynamics/Joints/b2Joint.h>
23 
36 {
38  {
39  type = e_revoluteJoint;
40  localAnchorA.Set(0.0f, 0.0f);
41  localAnchorB.Set(0.0f, 0.0f);
42  referenceAngle = 0.0f;
43  lowerAngle = 0.0f;
44  upperAngle = 0.0f;
45  maxMotorTorque = 0.0f;
46  motorSpeed = 0.0f;
47  enableLimit = false;
48  enableMotor = false;
49  }
50 
53  void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
54 
57 
60 
62  float32 referenceAngle;
63 
66 
68  float32 lowerAngle;
69 
71  float32 upperAngle;
72 
75 
77  float32 motorSpeed;
78 
81  float32 maxMotorTorque;
82 };
83 
90 class b2RevoluteJoint : public b2Joint
91 {
92 public:
93  b2Vec2 GetAnchorA() const;
94  b2Vec2 GetAnchorB() const;
95 
97  const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
98 
100  const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
101 
103  float32 GetReferenceAngle() const { return m_referenceAngle; }
104 
106  float32 GetJointAngle() const;
107 
109  float32 GetJointSpeed() const;
110 
112  bool IsLimitEnabled() const;
113 
115  void EnableLimit(bool flag);
116 
118  float32 GetLowerLimit() const;
119 
121  float32 GetUpperLimit() const;
122 
124  void SetLimits(float32 lower, float32 upper);
125 
127  bool IsMotorEnabled() const;
128 
130  void EnableMotor(bool flag);
131 
133  void SetMotorSpeed(float32 speed);
134 
136  float32 GetMotorSpeed() const;
137 
139  void SetMaxMotorTorque(float32 torque);
140  float32 GetMaxMotorTorque() const { return m_maxMotorTorque; }
141 
144  b2Vec2 GetReactionForce(float32 inv_dt) const;
145 
148  float32 GetReactionTorque(float32 inv_dt) const;
149 
152  float32 GetMotorTorque(float32 inv_dt) const;
153 
155  void Dump();
156 
157 protected:
158 
159  friend class b2Joint;
160  friend class b2GearJoint;
161 
163 
164  void InitVelocityConstraints(const b2SolverData& data);
165  void SolveVelocityConstraints(const b2SolverData& data);
166  bool SolvePositionConstraints(const b2SolverData& data);
167 
168  // Solver shared
169  b2Vec2 m_localAnchorA;
170  b2Vec2 m_localAnchorB;
171  b2Vec3 m_impulse;
172  float32 m_motorImpulse;
173 
174  bool m_enableMotor;
175  float32 m_maxMotorTorque;
176  float32 m_motorSpeed;
177 
178  bool m_enableLimit;
179  float32 m_referenceAngle;
180  float32 m_lowerAngle;
181  float32 m_upperAngle;
182 
183  // Solver temp
184  int32 m_indexA;
185  int32 m_indexB;
186  b2Vec2 m_rA;
187  b2Vec2 m_rB;
188  b2Vec2 m_localCenterA;
189  b2Vec2 m_localCenterB;
190  float32 m_invMassA;
191  float32 m_invMassB;
192  float32 m_invIA;
193  float32 m_invIB;
194  b2Mat33 m_mass; // effective mass for point-to-point constraint.
195  float32 m_motorMass; // effective mass for motor/limit angular constraint.
196  b2LimitState m_limitState;
197 };
198 
199 inline float32 b2RevoluteJoint::GetMotorSpeed() const
200 {
201  return m_motorSpeed;
202 }
203 
204 #endif
A 2D column vector with 3 elements.
Definition: b2Math.h:144
bool IsLimitEnabled() const
Is the joint limit enabled?
Definition: b2RevoluteJoint.cpp:443
b2Body * bodyA
The first attached body.
Definition: b2Joint.h:92
float32 GetJointSpeed() const
Get the current joint angle speed in radians per second.
Definition: b2RevoluteJoint.cpp:405
float32 motorSpeed
The desired motor speed. Usually in radians per second.
Definition: b2RevoluteJoint.h:77
void Initialize(b2Body *bodyA, b2Body *bodyB, const b2Vec2 &anchor)
Definition: b2RevoluteJoint.cpp:36
A 3-by-3 matrix. Stored in column-major order.
Definition: b2Math.h:257
void EnableMotor(bool flag)
Enable/disable the joint motor.
Definition: b2RevoluteJoint.cpp:417
b2Body * bodyB
The second attached body.
Definition: b2Joint.h:95
float32 GetUpperLimit() const
Get the upper joint limit in radians.
Definition: b2RevoluteJoint.cpp:464
b2Vec2 GetAnchorB() const
Get the anchor point on bodyB in world coordinates.
Definition: b2RevoluteJoint.cpp:382
bool enableMotor
A flag to enable the joint motor.
Definition: b2RevoluteJoint.h:74
void SetMaxMotorTorque(float32 torque)
Set the maximum motor torque, usually in N-m.
Definition: b2RevoluteJoint.cpp:436
float32 GetJointAngle() const
Get the current joint angle in radians.
Definition: b2RevoluteJoint.cpp:398
Definition: b2Joint.h:103
b2Vec2 localAnchorB
The local anchor point relative to bodyB's origin.
Definition: b2RevoluteJoint.h:59
float32 lowerAngle
The lower angle for the joint limit (radians).
Definition: b2RevoluteJoint.h:68
void Set(float32 x_, float32 y_)
Set this vector to some specified coordinates.
Definition: b2Math.h:65
void Dump()
Dump to b2Log.
Definition: b2RevoluteJoint.cpp:483
const b2Vec2 & GetLocalAnchorA() const
The local anchor point relative to bodyA's origin.
Definition: b2RevoluteJoint.h:97
float32 GetReferenceAngle() const
Get the reference angle.
Definition: b2RevoluteJoint.h:103
void SetMotorSpeed(float32 speed)
Set the motor speed in radians per second.
Definition: b2RevoluteJoint.cpp:429
float32 GetMotorSpeed() const
Get the motor speed in radians per second.
Definition: b2RevoluteJoint.h:199
Definition: b2GearJoint.h:56
float32 referenceAngle
The bodyB angle minus bodyA angle in the reference state (radians).
Definition: b2RevoluteJoint.h:62
b2Vec2 localAnchorA
The local anchor point relative to bodyA's origin.
Definition: b2RevoluteJoint.h:56
b2JointType type
The joint type is set automatically for concrete joint types.
Definition: b2Joint.h:86
b2Vec2 GetAnchorA() const
Get the anchor point on bodyA in world coordinates.
Definition: b2RevoluteJoint.cpp:377
Solver Data.
Definition: b2TimeStep.h:63
bool IsMotorEnabled() const
Is the joint motor enabled?
Definition: b2RevoluteJoint.cpp:412
const b2Vec2 & GetLocalAnchorB() const
The local anchor point relative to bodyB's origin.
Definition: b2RevoluteJoint.h:100
float32 upperAngle
The upper angle for the joint limit (radians).
Definition: b2RevoluteJoint.h:71
void EnableLimit(bool flag)
Enable/disable the joint limit.
Definition: b2RevoluteJoint.cpp:448
Definition: b2RevoluteJoint.h:90
Joint definitions are used to construct joints.
Definition: b2Joint.h:74
bool enableLimit
A flag to enable joint limits.
Definition: b2RevoluteJoint.h:65
A rigid body. These are created via b2World::CreateBody.
Definition: b2Body.h:126
Definition: b2RevoluteJoint.h:35
float32 GetLowerLimit() const
Get the lower joint limit in radians.
Definition: b2RevoluteJoint.cpp:459
float32 maxMotorTorque
Definition: b2RevoluteJoint.h:81
A 2D column vector.
Definition: b2Math.h:53
float32 GetMotorTorque(float32 inv_dt) const
Definition: b2RevoluteJoint.cpp:424
void SetLimits(float32 lower, float32 upper)
Set the joint limits in radians.
Definition: b2RevoluteJoint.cpp:469
b2Vec2 GetReactionForce(float32 inv_dt) const
Definition: b2RevoluteJoint.cpp:387
float32 GetReactionTorque(float32 inv_dt) const
Definition: b2RevoluteJoint.cpp:393