// Geometric Tools, Inc.
// http://www.geometrictools.com
// Copyright (c) 1998-2005.  All Rights Reserved
//
// The Wild Magic Library (WM3) source code is supplied under the terms of
// the license agreement
//     http://www.geometrictools.com/License/WildMagic3License.pdf
// and may not be copied or disclosed except in accordance with the terms
// of that agreement.

#ifndef PHYSICSMODULE_H
#define PHYSICSMODULE_H

#include "Wm3OdeSolver.h"

class PhysicsModule
{
public:
    // construction and destruction
    PhysicsModule ();
    ~PhysicsModule ();

    // initialize the differential equation solver
    void Initialize (double dTime, double dDeltaTime, double dX, double dY,
        double dTheta, double dXDot, double dYDot, double dThetaDot);

    // access the current state
    double GetTime () const;
    double GetDeltaTime () const;
    double GetX () const;
    double GetXDot () const;
    double GetY () const;
    double GetYDot () const;
    double GetTheta () const;
    double GetThetaDot () const;
    void Get (double& rdX1, double& rdY1, double& rdX2, double& rdY2) const;

    // take a single step of the solver
    void Update ();

    // physical constants   // symbols used in the Game Physics book
    double Length;          // L1 = L2 = L/2
    double MassDensity;     // delta0
    double Friction;        // c

protected:
    // state and auxiliary variables
    double m_dTime, m_dDeltaTime;
    double m_adState[6], m_adAux[9];
    double m_dHalfLength;

    // integrands for the generalized forces
    static double FXIntegrand (double dL, void* pvData);
    static double FYIntegrand (double dL, void* pvData);
    static double FThetaIntegrand (double dL, void* pvData);

    // ODE solver (specific solver assigned in the cpp file)
    Wm3::OdeSolverd* m_pkSolver;
    static void OdeFunction (double dTime, const double* adState,
        void* pvData, double* adFValue);

    // integration parameter
    static int ms_iOrder;
};

#include "PhysicsModule.inl"

#endif



