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1 /*
2 * Copyright (c) 2006-2012 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 */
19 #ifndef B2_MOTOR_JOINT_H
20 #define B2_MOTOR_JOINT_H
22 #include <Box2D/Dynamics/Joints/b2Joint.h>
25 struct b2MotorJointDef : public b2JointDef
26 {
28  {
29  type = e_motorJoint;
31  angularOffset = 0.0f;
32  maxForce = 1.0f;
33  maxTorque = 1.0f;
34  correctionFactor = 0.3f;
35  }
44  float32 angularOffset;
47  float32 maxForce;
50  float32 maxTorque;
54 };
59 class b2MotorJoint : public b2Joint
60 {
61 public:
62  b2Vec2 GetAnchorA() const;
63  b2Vec2 GetAnchorB() const;
65  b2Vec2 GetReactionForce(float32 inv_dt) const;
66  float32 GetReactionTorque(float32 inv_dt) const;
69  void SetLinearOffset(const b2Vec2& linearOffset);
70  const b2Vec2& GetLinearOffset() const;
73  void SetAngularOffset(float32 angularOffset);
74  float32 GetAngularOffset() const;
77  void SetMaxForce(float32 force);
80  float32 GetMaxForce() const;
83  void SetMaxTorque(float32 torque);
86  float32 GetMaxTorque() const;
89  void SetCorrectionFactor(float32 factor);
92  float32 GetCorrectionFactor() const;
95  void Dump();
97 protected:
99  friend class b2Joint;
101  b2MotorJoint(const b2MotorJointDef* def);
103  void InitVelocityConstraints(const b2SolverData& data);
104  void SolveVelocityConstraints(const b2SolverData& data);
105  bool SolvePositionConstraints(const b2SolverData& data);
107  // Solver shared
108  b2Vec2 m_linearOffset;
109  float32 m_angularOffset;
110  b2Vec2 m_linearImpulse;
111  float32 m_angularImpulse;
112  float32 m_maxForce;
113  float32 m_maxTorque;
114  float32 m_correctionFactor;
116  // Solver temp
117  int32 m_indexA;
118  int32 m_indexB;
119  b2Vec2 m_rA;
120  b2Vec2 m_rB;
121  b2Vec2 m_localCenterA;
122  b2Vec2 m_localCenterB;
123  b2Vec2 m_linearError;
124  float32 m_angularError;
125  float32 m_invMassA;
126  float32 m_invMassB;
127  float32 m_invIA;
128  float32 m_invIB;
129  b2Mat22 m_linearMass;
130  float32 m_angularMass;
131 };
133 #endif
b2Vec2 GetAnchorA() const
Get the anchor point on bodyA in world coordinates.
Definition: b2MotorJoint.cpp:206
b2Body * bodyA
The first attached body.
Definition: b2Joint.h:92
Definition: b2MotorJoint.h:59
void SetMaxTorque(float32 torque)
Set the maximum friction torque in N*m.
Definition: b2MotorJoint.cpp:237
void Dump()
Dump to b2Log.
Definition: b2MotorJoint.cpp:289
void SetLinearOffset(const b2Vec2 &linearOffset)
Set/get the target linear offset, in frame A, in meters.
Definition: b2MotorJoint.cpp:259
float32 GetMaxTorque() const
Get the maximum friction torque in N*m.
Definition: b2MotorJoint.cpp:243
b2Body * bodyB
The second attached body.
Definition: b2Joint.h:95
b2Vec2 GetAnchorB() const
Get the anchor point on bodyB in world coordinates.
Definition: b2MotorJoint.cpp:211
void SetMaxForce(float32 force)
Set the maximum friction force in N.
Definition: b2MotorJoint.cpp:226
float32 maxTorque
The maximum motor torque in N-m.
Definition: b2MotorJoint.h:50
Motor joint definition.
Definition: b2MotorJoint.h:25
Definition: b2Joint.h:103
void SetZero()
Set this vector to all zeros.
Definition: b2Math.h:65
float32 angularOffset
The bodyB angle minus bodyA angle in radians.
Definition: b2MotorJoint.h:44
b2Vec2 GetReactionForce(float32 inv_dt) const
Get the reaction force on bodyB at the joint anchor in Newtons.
Definition: b2MotorJoint.cpp:216
float32 GetMaxForce() const
Get the maximum friction force in N.
Definition: b2MotorJoint.cpp:232
b2JointType type
The joint type is set automatically for concrete joint types.
Definition: b2Joint.h:86
float32 GetReactionTorque(float32 inv_dt) const
Get the reaction torque on bodyB in N*m.
Definition: b2MotorJoint.cpp:221
Solver Data.
Definition: b2TimeStep.h:65
float32 maxForce
The maximum motor force in N.
Definition: b2MotorJoint.h:47
A 2-by-2 matrix. Stored in column-major order.
Definition: b2Math.h:244
float32 correctionFactor
Position correction factor in the range [0,1].
Definition: b2MotorJoint.h:53
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 GetCorrectionFactor() const
Get the position correction factor in the range [0,1].
Definition: b2MotorJoint.cpp:254
void SetCorrectionFactor(float32 factor)
Set the position correction factor in the range [0,1].
Definition: b2MotorJoint.cpp:248
A 2D column vector.
Definition: b2Math.h:56
void SetAngularOffset(float32 angularOffset)
Set/get the target angular offset, in radians.
Definition: b2MotorJoint.cpp:274
b2Vec2 linearOffset
Position of bodyB minus the position of bodyA, in bodyA's frame, in meters.
Definition: b2MotorJoint.h:41
void Initialize(b2Body *bodyA, b2Body *bodyB)
Initialize the bodies and offsets using the current transforms.
Definition: b2MotorJoint.cpp:35