1/*
2* Copyright (c) 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_ROPE_H
20#define B2_ROPE_H
21
22#include <Box2D/Common/b2Math.h>
23
24class b2Draw;
25
26///
27struct b2RopeDef
28{
29 b2RopeDef()
30 {
31 vertices = NULL;
32 count = 0;
33 masses = NULL;
34 gravity.SetZero();
35 damping = 0.1f;
36 k2 = 0.9f;
37 k3 = 0.1f;
38 }
39
40 ///
41 b2Vec2* vertices;
42
43 ///
44 int32 count;
45
46 ///
47 float32* masses;
48
49 ///
50 b2Vec2 gravity;
51
52 ///
53 float32 damping;
54
55 /// Stretching stiffness
56 float32 k2;
57
58 /// Bending stiffness. Values above 0.5 can make the simulation blow up.
59 float32 k3;
60};
61
62///
63class b2Rope
64{
65public:
66 b2Rope();
67 ~b2Rope();
68
69 ///
70 void Initialize(const b2RopeDef* def);
71
72 ///
73 void Step(float32 timeStep, int32 iterations);
74
75 ///
76 int32 GetVertexCount() const
77 {
78 return m_count;
79 }
80
81 ///
82 const b2Vec2* GetVertices() const
83 {
84 return m_ps;
85 }
86
87 ///
88 void Draw(b2Draw* draw) const;
89
90 ///
91 void SetAngle(float32 angle);
92
93private:
94
95 void SolveC2();
96 void SolveC3();
97
98 int32 m_count;
99 b2Vec2* m_ps;
100 b2Vec2* m_p0s;
101 b2Vec2* m_vs;
102
103 float32* m_ims;
104
105 float32* m_Ls;
106 float32* m_as;
107
108 b2Vec2 m_gravity;
109 float32 m_damping;
110
111 float32 m_k2;
112 float32 m_k3;
113};
114
115#endif
116