PidController.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

/*
 * Copyright (C) 2006-2010 - Frictional Games
 *
 * This file is part of HPL1 Engine.
 */

#ifndef HPL_PID_CONTROLLER_H
#define HPL_PID_CONTROLLER_H

#include "hpl1/algorithms.h"
#include "hpl1/engine/math/MathTypes.h"

namespace hpl {

template<class T>
class cPidController {
public:
    float p, i, d;
    // Constructors
    cPidController() {
        Reset();
    }
    cPidController(float afP, float afI, float afD, int alErrorNum) {
        p = afP;
        i = afI;
        d = afD;
        SetErrorNum(alErrorNum);
        Reset();
    }

    // Public

    //------------------------------------
    T Output(T aError, float afTimeStep) {
        mvErrors[mlErrorNum] = aError;
        mvTimeSteps[mlErrorNum] = afTimeStep;

        integral = 0;
        size_t lCount = mvErrors.size();
        for (size_t error = 0; error < lCount; ++error) {
            integral += mvErrors[error] * mvTimeSteps[error];
        }

        derivative = 0.0f;
        if (mlLastNum >= 0) {
            derivative = (mvErrors[mlErrorNum] - mvErrors[mlLastNum]) / afTimeStep;
        }

        mlLastNum = mlErrorNum;
        mlErrorNum++;
        if (mlErrorNum >= (int)mvErrors.size())
            mlErrorNum = 0;

        return mvErrors[mlLastNum] * p + integral * i + derivative * d;
    }

    //------------------------------------

    void SetErrorNum(int alErrorNum) {
        mvErrors.resize(alErrorNum);
        Hpl1::resizeAndFill(mvTimeSteps, alErrorNum, 0.f);
    }

    //------------------------------------

    void Reset() {
        mlErrorNum = 0;
        mlLastNum = -1;
        Common::fill(mvTimeSteps.begin(), mvTimeSteps.end(), 0);

        integral = 0;
        derivative = 0;
    }

    //------------------------------------

    T GetLastError() {
        if (mlLastNum >= 0)
            return mvErrors[mlLastNum];
        return 0;
    }

    T GetLastDerivative() {
        return derivative;
    }

    T GetLastIntegral() {
        return integral;
    }

    //------------------------------------

private:
    Common::Array<T> mvErrors;
    Common::Array<float> mvTimeSteps;

    T integral, derivative;

    int mlErrorNum;
    int mlLastNum;
};

//---------------------------------

typedef cPidController<float> cPidControllerf;
typedef cPidController<cVector3f> cPidControllerVec3;

} // namespace hpl

#endif // HPL_PID_CONTROLLER_H