b2ContactSolver.h

/*
* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/

#ifndef B2_CONTACT_SOLVER_H
#define B2_CONTACT_SOLVER_H

#include <Box2D/Common/b2Math.h>
#include <Box2D/Collision/b2Collision.h>
#include <Box2D/Dynamics/b2TimeStep.h>

class b2Contact;
class b2Body;
class b2StackAllocator;
struct b2ContactPositionConstraint;

struct b2VelocityConstraintPoint
{
    b2Vec2 rA;
    b2Vec2 rB;
    float32 normalImpulse;
    float32 tangentImpulse;
    float32 normalMass;
    float32 tangentMass;
    float32 velocityBias;
};

struct b2ContactVelocityConstraint
{
    b2VelocityConstraintPoint points[b2_maxManifoldPoints];
    b2Vec2 normal;
    b2Mat22 normalMass;
    b2Mat22 K;
    int32 indexA;
    int32 indexB;
    float32 invMassA, invMassB;
    float32 invIA, invIB;
    float32 friction;
    float32 restitution;
    float32 tangentSpeed;
    int32 pointCount;
    int32 contactIndex;
};

struct b2ContactSolverDef
{
    b2TimeStep step;
    b2Contact** contacts;
    int32 count;
    b2Position* positions;
    b2Velocity* velocities;
    b2StackAllocator* allocator;
};

class b2ContactSolver
{
public:
    b2ContactSolver(b2ContactSolverDef* def);
    ~b2ContactSolver();

    void InitializeVelocityConstraints();

    void WarmStart();
    void SolveVelocityConstraints();
    void StoreImpulses();

    bool SolvePositionConstraints();
    bool SolveTOIPositionConstraints(int32 toiIndexA, int32 toiIndexB);

    b2TimeStep m_step;
    b2Position* m_positions;
    b2Velocity* m_velocities;
    b2StackAllocator* m_allocator;
    b2ContactPositionConstraint* m_positionConstraints;
    b2ContactVelocityConstraint* m_velocityConstraints;
    b2Contact** m_contacts;
    int m_count;
};

#endif