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1 /*
2 * Copyright (c) 2006-2011 Erin Catto
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 */
22 #include <Box2D/Dynamics/Joints/b2Joint.h>
31 {
33  {
34  type = e_prismaticJoint;
37  localAxisA.Set(1.0f, 0.0f);
38  referenceAngle = 0.0f;
39  enableLimit = false;
40  lowerTranslation = 0.0f;
41  upperTranslation = 0.0f;
42  enableMotor = false;
43  maxMotorForce = 0.0f;
44  motorSpeed = 0.0f;
45  }
49  void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor, const b2Vec2& axis);
61  float32 referenceAngle;
76  float32 maxMotorForce;
79  float32 motorSpeed;
80 };
86 class b2PrismaticJoint : public b2Joint
87 {
88 public:
89  b2Vec2 GetAnchorA() const;
90  b2Vec2 GetAnchorB() const;
92  b2Vec2 GetReactionForce(float32 inv_dt) const;
93  float32 GetReactionTorque(float32 inv_dt) const;
96  const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
99  const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
102  const b2Vec2& GetLocalAxisA() const { return m_localXAxisA; }
105  float32 GetReferenceAngle() const { return m_referenceAngle; }
108  float32 GetJointTranslation() const;
111  float32 GetJointSpeed() const;
114  bool IsLimitEnabled() const;
117  void EnableLimit(bool flag);
120  float32 GetLowerLimit() const;
123  float32 GetUpperLimit() const;
126  void SetLimits(float32 lower, float32 upper);
129  bool IsMotorEnabled() const;
132  void EnableMotor(bool flag);
135  void SetMotorSpeed(float32 speed);
138  float32 GetMotorSpeed() const;
141  void SetMaxMotorForce(float32 force);
142  float32 GetMaxMotorForce() const { return m_maxMotorForce; }
145  float32 GetMotorForce(float32 inv_dt) const;
148  void Dump();
150 protected:
151  friend class b2Joint;
152  friend class b2GearJoint;
155  void InitVelocityConstraints(const b2SolverData& data);
156  void SolveVelocityConstraints(const b2SolverData& data);
157  bool SolvePositionConstraints(const b2SolverData& data);
159  // Solver shared
160  b2Vec2 m_localAnchorA;
161  b2Vec2 m_localAnchorB;
162  b2Vec2 m_localXAxisA;
163  b2Vec2 m_localYAxisA;
164  float32 m_referenceAngle;
165  b2Vec3 m_impulse;
166  float32 m_motorImpulse;
167  float32 m_lowerTranslation;
168  float32 m_upperTranslation;
169  float32 m_maxMotorForce;
170  float32 m_motorSpeed;
171  bool m_enableLimit;
172  bool m_enableMotor;
173  b2LimitState m_limitState;
175  // Solver temp
176  int32 m_indexA;
177  int32 m_indexB;
178  b2Vec2 m_localCenterA;
179  b2Vec2 m_localCenterB;
180  float32 m_invMassA;
181  float32 m_invMassB;
182  float32 m_invIA;
183  float32 m_invIB;
184  b2Vec2 m_axis, m_perp;
185  float32 m_s1, m_s2;
186  float32 m_a1, m_a2;
187  b2Mat33 m_K;
188  float32 m_motorMass;
189 };
191 inline float32 b2PrismaticJoint::GetMotorSpeed() const
192 {
193  return m_motorSpeed;
194 }
196 #endif
b2Vec2 GetReactionForce(float32 inv_dt) const
Get the reaction force on bodyB at the joint anchor in Newtons.
Definition: b2PrismaticJoint.cpp:494
const b2Vec2 & GetLocalAnchorB() const
The local anchor point relative to bodyB's origin.
Definition: b2PrismaticJoint.h:99
const b2Vec2 & GetLocalAnchorA() const
The local anchor point relative to bodyA's origin.
Definition: b2PrismaticJoint.h:96
void EnableMotor(bool flag)
Enable/disable the joint motor.
Definition: b2PrismaticJoint.cpp:580
A 3D column vector with 3 elements.
Definition: b2Math.h:171
bool enableMotor
Enable/disable the joint motor.
Definition: b2PrismaticJoint.h:73
float32 GetJointSpeed() const
Get the current joint translation speed, usually in meters per second.
Definition: b2PrismaticJoint.cpp:515
bool enableLimit
Enable/disable the joint limit.
Definition: b2PrismaticJoint.h:64
b2Body * bodyA
The first attached body.
Definition: b2Joint.h:92
b2Vec2 GetAnchorA() const
Get the anchor point on bodyA in world coordinates.
Definition: b2PrismaticJoint.cpp:484
A 3-by-3 matrix. Stored in column-major order.
Definition: b2Math.h:318
float32 lowerTranslation
The lower translation limit, usually in meters.
Definition: b2PrismaticJoint.h:67
float32 upperTranslation
The upper translation limit, usually in meters.
Definition: b2PrismaticJoint.h:70
float32 GetJointTranslation() const
Get the current joint translation, usually in meters.
Definition: b2PrismaticJoint.cpp:504
Definition: b2PrismaticJoint.h:30
b2Body * bodyB
The second attached body.
Definition: b2Joint.h:95
void SetMotorSpeed(float32 speed)
Set the motor speed, usually in meters per second.
Definition: b2PrismaticJoint.cpp:587
b2Vec2 GetAnchorB() const
Get the anchor point on bodyB in world coordinates.
Definition: b2PrismaticJoint.cpp:489
void SetLimits(float32 lower, float32 upper)
Set the joint limits, usually in meters.
Definition: b2PrismaticJoint.cpp:562
Definition: b2Joint.h:103
b2Vec2 localAxisA
The local translation unit axis in bodyA.
Definition: b2PrismaticJoint.h:58
Definition: b2PrismaticJoint.h:86
const b2Vec2 & GetLocalAxisA() const
The local joint axis relative to bodyA.
Definition: b2PrismaticJoint.h:102
float32 GetReactionTorque(float32 inv_dt) const
Get the reaction torque on bodyB in N*m.
Definition: b2PrismaticJoint.cpp:499
void Set(float32 x_, float32 y_)
Set this vector to some specified coordinates.
Definition: b2Math.h:68
float32 motorSpeed
The desired motor speed in radians per second.
Definition: b2PrismaticJoint.h:79
void SetZero()
Set this vector to all zeros.
Definition: b2Math.h:65
float32 maxMotorForce
The maximum motor torque, usually in N-m.
Definition: b2PrismaticJoint.h:76
bool IsLimitEnabled() const
Is the joint limit enabled?
Definition: b2PrismaticJoint.cpp:536
Definition: b2GearJoint.h:56
b2JointType type
The joint type is set automatically for concrete joint types.
Definition: b2Joint.h:86
Solver Data.
Definition: b2TimeStep.h:65
float32 GetLowerLimit() const
Get the lower joint limit, usually in meters.
Definition: b2PrismaticJoint.cpp:552
b2Vec2 localAnchorA
The local anchor point relative to bodyA's origin.
Definition: b2PrismaticJoint.h:52
b2Vec2 localAnchorB
The local anchor point relative to bodyB's origin.
Definition: b2PrismaticJoint.h:55
Joint definitions are used to construct joints.
Definition: b2Joint.h:74
A rigid body. These are created via b2World::CreateBody.
Definition: b2Body.h:132
float32 referenceAngle
The constrained angle between the bodies: bodyB_angle - bodyA_angle.
Definition: b2PrismaticJoint.h:61
float32 GetReferenceAngle() const
Get the reference angle.
Definition: b2PrismaticJoint.h:105
void Dump()
Dump to b2Log.
Definition: b2PrismaticJoint.cpp:606
void EnableLimit(bool flag)
Enable/disable the joint limit.
Definition: b2PrismaticJoint.cpp:541
A 2D column vector.
Definition: b2Math.h:56
void Initialize(b2Body *bodyA, b2Body *bodyB, const b2Vec2 &anchor, const b2Vec2 &axis)
Definition: b2PrismaticJoint.cpp:90
bool IsMotorEnabled() const
Is the joint motor enabled?
Definition: b2PrismaticJoint.cpp:575
float32 GetMotorForce(float32 inv_dt) const
Get the current motor force given the inverse time step, usually in N.
Definition: b2PrismaticJoint.cpp:601
float32 GetUpperLimit() const
Get the upper joint limit, usually in meters.
Definition: b2PrismaticJoint.cpp:557
float32 GetMotorSpeed() const
Get the motor speed, usually in meters per second.
Definition: b2PrismaticJoint.h:191
void SetMaxMotorForce(float32 force)
Set the maximum motor force, usually in N.
Definition: b2PrismaticJoint.cpp:594