b2_contact_solver.h

Go to the documentation of this file.

// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#ifndef B2_CONTACT_SOLVER_H
#define B2_CONTACT_SOLVER_H

#include "box2d/b2_collision.h"
#include "box2d/b2_math.h"
#include "box2d/b2_time_step.h"

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

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

struct b2ContactVelocityConstraint
{
        b2VelocityConstraintPoint points[b2_maxManifoldPoints];
        b2Vec2 normal;
        b2Mat22 normalMass;
        b2Mat22 K;
        int32 indexA;
        int32 indexB;
        float invMassA, invMassB;
        float invIA, invIB;
        float friction;
        float restitution;
        float threshold;
        float 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