Box2D: /build/box2d/src/box2d-2.4.1/include/box2d/b2_rope.h Source File

| Box2D 2.4.1 A 2D physics engine for games

b2_rope.h
1 // MIT License
2
3 // Copyright (c) 2019 Erin Catto
4
5 // Permission is hereby granted, free of charge, to any person obtaining a copy
6 // of this software and associated documentation files (the "Software"), to deal
7 // in the Software without restriction, including without limitation the rights
8 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 // copies of the Software, and to permit persons to whom the Software is
10 // furnished to do so, subject to the following conditions:
11
12 // The above copyright notice and this permission notice shall be included in all
13 // copies or substantial portions of the Software.
14
15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 // SOFTWARE.
22
23 #ifndef B2_ROPE_H
24 #define B2_ROPE_H
25
26 #include "b2_api.h"
27 #include "b2_math.h"
28
29 class b2Draw;
30 struct b2RopeStretch;
31 struct b2RopeBend;
32
33 enum b2StretchingModel
34 {
35 b2_pbdStretchingModel,
36 b2_xpbdStretchingModel
37 };
38
39 enum b2BendingModel
40 {
41 b2_springAngleBendingModel = 0,
42 b2_pbdAngleBendingModel,
43 b2_xpbdAngleBendingModel,
44 b2_pbdDistanceBendingModel,
45 b2_pbdHeightBendingModel,
46 b2_pbdTriangleBendingModel
47 };
48
50 struct B2_API b2RopeTuning
51 {
52 b2RopeTuning()
53 {
54 stretchingModel = b2_pbdStretchingModel;
55 bendingModel = b2_pbdAngleBendingModel;
56 damping = 0.0f;
57 stretchStiffness = 1.0f;
58 bendStiffness = 0.5f;
59 bendHertz = 1.0f;
60 bendDamping = 0.0f;
61 isometric = false;
62 fixedEffectiveMass = false;
63 warmStart = false;
64 }
65
66 b2StretchingModel stretchingModel;
67 b2BendingModel bendingModel;
68 float damping;
69 float stretchStiffness;
70 float stretchHertz;
71 float stretchDamping;
72 float bendStiffness;
73 float bendHertz;
74 float bendDamping;
75 bool isometric;
76 bool fixedEffectiveMass;
77 bool warmStart;
78 };
79
81 struct B2_API b2RopeDef
82 {
83 b2RopeDef()
84 {
85 position.SetZero();
86 vertices = nullptr;
87 count = 0;
88 masses = nullptr;
89 gravity.SetZero();
90 }
91
92 b2Vec2 position;
93 b2Vec2* vertices;
94 int32 count;
95 float* masses;
96 b2Vec2 gravity;
97 b2RopeTuning tuning;
98 };
99
101 class B2_API b2Rope
102 {
103 public:
104 b2Rope();
105 ~b2Rope();
106
108 void Create(const b2RopeDef& def);
109
111 void SetTuning(const b2RopeTuning& tuning);
112
114 void Step(float timeStep, int32 iterations, const b2Vec2& position);
115
117 void Reset(const b2Vec2& position);
118
120 void Draw(b2Draw* draw) const;
121
122 private:
123
124 void SolveStretch_PBD();
125 void SolveStretch_XPBD(float dt);
126 void SolveBend_PBD_Angle();
127 void SolveBend_XPBD_Angle(float dt);
128 void SolveBend_PBD_Distance();
129 void SolveBend_PBD_Height();
130 void SolveBend_PBD_Triangle();
131 void ApplyBendForces(float dt);
132
133 b2Vec2 m_position;
134
135 int32 m_count;
136 int32 m_stretchCount;
137 int32 m_bendCount;
138
139 b2RopeStretch* m_stretchConstraints;
140 b2RopeBend* m_bendConstraints;
141
142 b2Vec2* m_bindPositions;
143 b2Vec2* m_ps;
144 b2Vec2* m_p0s;
145 b2Vec2* m_vs;
146
147 float* m_invMasses;
148 b2Vec2 m_gravity;
149
150 b2RopeTuning m_tuning;
151 };
152
153 #endif
b2Vec2
A 2D column vector.
Definition: b2_math.h:42
b2RopeDef
Definition: b2_rope.h:82
b2Draw
Definition: b2_draw.h:49
b2RopeTuning
Definition: b2_rope.h:51
b2Rope
Definition: b2_rope.h:102