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

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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
29class b2Draw;
30struct b2RopeStretch;
31struct b2RopeBend;
32
33enum b2StretchingModel
34{
35 b2_pbdStretchingModel,
36 b2_xpbdStretchingModel
37};
38
39enum 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{
103public:
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
122private:
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
b2Draw
Definition b2_draw.h:49
b2Rope
Definition b2_rope.h:102
b2RopeDef
Definition b2_rope.h:82
b2RopeTuning
Definition b2_rope.h:51
b2Vec2
A 2D column vector.
Definition b2_math.h:42