Box2D  2.3.0
A 2D Physics Engine for Games
b2ContactSolver.h
1 /*
2 * Copyright (c) 2006-2009 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_CONTACT_SOLVER_H
20 #define B2_CONTACT_SOLVER_H
21 
22 #include <Box2D/Common/b2Math.h>
23 #include <Box2D/Collision/b2Collision.h>
24 #include <Box2D/Dynamics/b2TimeStep.h>
25 
26 class b2Contact;
27 class b2Body;
28 class b2StackAllocator;
29 struct b2ContactPositionConstraint;
30 
31 struct b2VelocityConstraintPoint
32 {
33  b2Vec2 rA;
34  b2Vec2 rB;
35  float32 normalImpulse;
36  float32 tangentImpulse;
37  float32 normalMass;
38  float32 tangentMass;
39  float32 velocityBias;
40 };
41 
42 struct b2ContactVelocityConstraint
43 {
44  b2VelocityConstraintPoint points[b2_maxManifoldPoints];
45  b2Vec2 normal;
46  b2Mat22 normalMass;
47  b2Mat22 K;
48  int32 indexA;
49  int32 indexB;
50  float32 invMassA, invMassB;
51  float32 invIA, invIB;
52  float32 friction;
53  float32 restitution;
54  float32 tangentSpeed;
55  int32 pointCount;
56  int32 contactIndex;
57 };
58 
59 struct b2ContactSolverDef
60 {
61  b2TimeStep step;
62  b2Contact** contacts;
63  int32 count;
64  b2Position* positions;
65  b2Velocity* velocities;
66  b2StackAllocator* allocator;
67 };
68 
69 class b2ContactSolver
70 {
71 public:
72  b2ContactSolver(b2ContactSolverDef* def);
73  ~b2ContactSolver();
74 
75  void InitializeVelocityConstraints();
76 
77  void WarmStart();
78  void SolveVelocityConstraints();
79  void StoreImpulses();
80 
81  bool SolvePositionConstraints();
82  bool SolveTOIPositionConstraints(int32 toiIndexA, int32 toiIndexB);
83 
84  b2TimeStep m_step;
85  b2Position* m_positions;
86  b2Velocity* m_velocities;
87  b2StackAllocator* m_allocator;
88  b2ContactPositionConstraint* m_positionConstraints;
89  b2ContactVelocityConstraint* m_velocityConstraints;
90  b2Contact** m_contacts;
91  int m_count;
92 };
93 
94 #endif
95 
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