1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
|
// MIT License
// Copyright (c) 2019 Erin Catto
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#ifndef B2_WELD_JOINT_H
#define B2_WELD_JOINT_H
#include "b2_api.h"
#include "b2_joint.h"
/// Weld joint definition. You need to specify local anchor points
/// where they are attached and the relative body angle. The position
/// of the anchor points is important for computing the reaction torque.
struct B2_API b2WeldJointDef : public b2JointDef
{
b2WeldJointDef()
{
type = e_weldJoint;
localAnchorA.Set(0.0f, 0.0f);
localAnchorB.Set(0.0f, 0.0f);
referenceAngle = 0.0f;
stiffness = 0.0f;
damping = 0.0f;
}
/// Initialize the bodies, anchors, reference angle, stiffness, and damping.
/// @param bodyA the first body connected by this joint
/// @param bodyB the second body connected by this joint
/// @param anchor the point of connection in world coordinates
void Initialize(b2Body* bodyA, b2Body* bodyB, const b2Vec2& anchor);
/// The local anchor point relative to bodyA's origin.
b2Vec2 localAnchorA;
/// The local anchor point relative to bodyB's origin.
b2Vec2 localAnchorB;
/// The bodyB angle minus bodyA angle in the reference state (radians).
float referenceAngle;
/// The rotational stiffness in N*m
/// Disable softness with a value of 0
float stiffness;
/// The rotational damping in N*m*s
float damping;
};
/// A weld joint essentially glues two bodies together. A weld joint may
/// distort somewhat because the island constraint solver is approximate.
class B2_API b2WeldJoint : public b2Joint
{
public:
b2Vec2 GetAnchorA() const override;
b2Vec2 GetAnchorB() const override;
b2Vec2 GetReactionForce(float inv_dt) const override;
float GetReactionTorque(float inv_dt) const override;
/// The local anchor point relative to bodyA's origin.
const b2Vec2& GetLocalAnchorA() const { return m_localAnchorA; }
/// The local anchor point relative to bodyB's origin.
const b2Vec2& GetLocalAnchorB() const { return m_localAnchorB; }
/// Get the reference angle.
float GetReferenceAngle() const { return m_referenceAngle; }
/// Set/get stiffness in N*m
void SetStiffness(float hz) { m_stiffness = hz; }
float GetStiffness() const { return m_stiffness; }
/// Set/get damping in N*m*s
void SetDamping(float damping) { m_damping = damping; }
float GetDamping() const { return m_damping; }
/// Dump to b2Log
void Dump() override;
protected:
friend class b2Joint;
b2WeldJoint(const b2WeldJointDef* def);
void InitVelocityConstraints(const b2SolverData& data) override;
void SolveVelocityConstraints(const b2SolverData& data) override;
bool SolvePositionConstraints(const b2SolverData& data) override;
float m_stiffness;
float m_damping;
float m_bias;
// Solver shared
b2Vec2 m_localAnchorA;
b2Vec2 m_localAnchorB;
float m_referenceAngle;
float m_gamma;
b2Vec3 m_impulse;
// Solver temp
int32 m_indexA;
int32 m_indexB;
b2Vec2 m_rA;
b2Vec2 m_rB;
b2Vec2 m_localCenterA;
b2Vec2 m_localCenterB;
float m_invMassA;
float m_invMassB;
float m_invIA;
float m_invIB;
b2Mat33 m_mass;
};
#endif
|
