Box2D 2.3.0 A 2D Physics Engine for Games

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b2PulleyJoint.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.
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 */
18
19 #ifndef B2_PULLEY_JOINT_H
20 #define B2_PULLEY_JOINT_H
21
22 #include <Box2D/Dynamics/Joints/b2Joint.h>
23
24 const float32 b2_minPulleyLength = 2.0f;
25
28 struct b2PulleyJointDef : public b2JointDef
29 {
30 b2PulleyJointDef()
31 {
32 type = e_pulleyJoint;
33 groundAnchorA.Set(-1.0f, 1.0f);
34 groundAnchorB.Set(1.0f, 1.0f);
35 localAnchorA.Set(-1.0f, 0.0f);
36 localAnchorB.Set(1.0f, 0.0f);
37 lengthA = 0.0f;
38 lengthB = 0.0f;
39 ratio = 1.0f;
40 collideConnected = true;
41 }
42
44 void Initialize(b2Body* bodyA, b2Body* bodyB,
45 const b2Vec2& groundAnchorA, const b2Vec2& groundAnchorB,
46 const b2Vec2& anchorA, const b2Vec2& anchorB,
47 float32 ratio);
48
50 b2Vec2 groundAnchorA;
51
53 b2Vec2 groundAnchorB;
54
56 b2Vec2 localAnchorA;
57
59 b2Vec2 localAnchorB;
60
62 float32 lengthA;
63
65 float32 lengthB;
66
68 float32 ratio;
69 };
70
79 class b2PulleyJoint : public b2Joint
80 {
81 public:
82 b2Vec2 GetAnchorA() const;
83 b2Vec2 GetAnchorB() const;
84
85 b2Vec2 GetReactionForce(float32 inv_dt) const;
86 float32 GetReactionTorque(float32 inv_dt) const;
87
89 b2Vec2 GetGroundAnchorA() const;
90
92 b2Vec2 GetGroundAnchorB() const;
93
95 float32 GetLengthA() const;
96
98 float32 GetLengthB() const;
99
101 float32 GetRatio() const;
102
104 float32 GetCurrentLengthA() const;
105
107 float32 GetCurrentLengthB() const;
108
110 void Dump();
111
113 void ShiftOrigin(const b2Vec2& newOrigin);
114
115 protected:
116
117 friend class b2Joint;
118 b2PulleyJoint(const b2PulleyJointDef* data);
119
120 void InitVelocityConstraints(const b2SolverData& data);
121 void SolveVelocityConstraints(const b2SolverData& data);
122 bool SolvePositionConstraints(const b2SolverData& data);
123
124 b2Vec2 m_groundAnchorA;
125 b2Vec2 m_groundAnchorB;
126 float32 m_lengthA;
127 float32 m_lengthB;
128
129 // Solver shared
130 b2Vec2 m_localAnchorA;
131 b2Vec2 m_localAnchorB;
132 float32 m_constant;
133 float32 m_ratio;
134 float32 m_impulse;
135
136 // Solver temp
137 int32 m_indexA;
138 int32 m_indexB;
139 b2Vec2 m_uA;
140 b2Vec2 m_uB;
141 b2Vec2 m_rA;
142 b2Vec2 m_rB;
143 b2Vec2 m_localCenterA;
144 b2Vec2 m_localCenterB;
145 float32 m_invMassA;
146 float32 m_invMassB;
147 float32 m_invIA;
148 float32 m_invIB;
149 float32 m_mass;
150 };
151
152 #endif
b2PulleyJoint::GetReactionTorque
float32 GetReactionTorque(float32 inv_dt) const
Get the reaction torque on bodyB in N*m.
Definition: b2PulleyJoint.cpp:278
b2PulleyJoint::GetAnchorB
b2Vec2 GetAnchorB() const
Get the anchor point on bodyB in world coordinates.
Definition: b2PulleyJoint.cpp:267
b2JointDef::bodyA
b2Body * bodyA
The first attached body.
Definition: b2Joint.h:92
b2PulleyJoint::GetGroundAnchorA
b2Vec2 GetGroundAnchorA() const
Get the first ground anchor.
Definition: b2PulleyJoint.cpp:284
b2PulleyJoint::GetCurrentLengthA
float32 GetCurrentLengthA() const
Get the current length of the segment attached to bodyA.
Definition: b2PulleyJoint.cpp:309
b2PulleyJoint::GetLengthA
float32 GetLengthA() const
Get the current length of the segment attached to bodyA.
Definition: b2PulleyJoint.cpp:294
b2JointDef::bodyB
b2Body * bodyB
The second attached body.
Definition: b2Joint.h:95
b2PulleyJointDef::lengthB
float32 lengthB
The a reference length for the segment attached to bodyB.
Definition: b2PulleyJoint.h:65
b2PulleyJoint::ShiftOrigin
void ShiftOrigin(const b2Vec2 &newOrigin)
Implement b2Joint::ShiftOrigin.
Definition: b2PulleyJoint.cpp:344
b2Joint
Definition: b2Joint.h:103
b2PulleyJoint::GetRatio
float32 GetRatio() const
Get the pulley ratio.
Definition: b2PulleyJoint.cpp:304
b2PulleyJoint::GetCurrentLengthB
float32 GetCurrentLengthB() const
Get the current length of the segment attached to bodyB.
Definition: b2PulleyJoint.cpp:317
b2Vec2::Set
void Set(float32 x_, float32 y_)
Set this vector to some specified coordinates.
Definition: b2Math.h:65
b2PulleyJointDef::ratio
float32 ratio
The pulley ratio, used to simulate a block-and-tackle.
Definition: b2PulleyJoint.h:68
b2PulleyJoint::Dump
void Dump()
Dump joint to dmLog.
Definition: b2PulleyJoint.cpp:325
b2PulleyJoint::GetGroundAnchorB
b2Vec2 GetGroundAnchorB() const
Get the second ground anchor.
Definition: b2PulleyJoint.cpp:289
b2JointDef::type
b2JointType type
The joint type is set automatically for concrete joint types.
Definition: b2Joint.h:86
b2JointDef::collideConnected
bool collideConnected
Set this flag to true if the attached bodies should collide.
Definition: b2Joint.h:98
b2PulleyJoint::GetReactionForce
b2Vec2 GetReactionForce(float32 inv_dt) const
Get the reaction force on bodyB at the joint anchor in Newtons.
Definition: b2PulleyJoint.cpp:272
b2SolverData
Solver Data.
Definition: b2TimeStep.h:63
b2JointDef
Joint definitions are used to construct joints.
Definition: b2Joint.h:74
b2PulleyJointDef
Definition: b2PulleyJoint.h:28
b2Body
A rigid body. These are created via b2World::CreateBody.
Definition: b2Body.h:126
b2PulleyJointDef::groundAnchorA
b2Vec2 groundAnchorA
The first ground anchor in world coordinates. This point never moves.
Definition: b2PulleyJoint.h:50
b2PulleyJoint::GetLengthB
float32 GetLengthB() const
Get the current length of the segment attached to bodyB.
Definition: b2PulleyJoint.cpp:299
b2PulleyJointDef::lengthA
float32 lengthA
The a reference length for the segment attached to bodyA.
Definition: b2PulleyJoint.h:62
b2Vec2
A 2D column vector.
Definition: b2Math.h:53
b2PulleyJoint::GetAnchorA
b2Vec2 GetAnchorA() const
Get the anchor point on bodyA in world coordinates.
Definition: b2PulleyJoint.cpp:262
b2PulleyJointDef::localAnchorB
b2Vec2 localAnchorB
The local anchor point relative to bodyB&#39;s origin.
Definition: b2PulleyJoint.h:59
b2PulleyJointDef::localAnchorA
b2Vec2 localAnchorA
The local anchor point relative to bodyA&#39;s origin.
Definition: b2PulleyJoint.h:56
b2PulleyJoint
Definition: b2PulleyJoint.h:79
b2PulleyJointDef::Initialize
void Initialize(b2Body *bodyA, b2Body *bodyB, const b2Vec2 &groundAnchorA, const b2Vec2 &groundAnchorB, const b2Vec2 &anchorA, const b2Vec2 &anchorB, float32 ratio)
Initialize the bodies, anchors, lengths, max lengths, and ratio using the world anchors.
Definition: b2PulleyJoint.cpp:35
b2PulleyJointDef::groundAnchorB
b2Vec2 groundAnchorB
The second ground anchor in world coordinates. This point never moves.
Definition: b2PulleyJoint.h:53