brake.cpp

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/***************************************************************************

    file                 : brake.cpp
    created              : Sun Mar 19 00:05:26 CET 2000
    copyright            : (C) 2000-2026 by Eric Espie, Bernhard Wymann
    email                : berniw@bluewin.ch

 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "sim.h"

void SimBrakeConfig(void *hdle, const char *section, tBrake *brake)
{
    tdble diam, area, mu;

    diam     = GfParmGetNum(hdle, section, PRM_BRKDIAM, (char*)NULL, 0.2f);
    area     = GfParmGetNum(hdle, section, PRM_BRKAREA, (char*)NULL, 0.002f);
    mu       = GfParmGetNum(hdle, section, PRM_MU, (char*)NULL, 0.30f);
    brake->coeff = diam * 0.5f * area * mu;

    brake->I = GfParmGetNum(hdle, section, PRM_INERTIA, (char*)NULL, 0.13f);
    brake->radius = diam/2.0f;
}


void SimBrakeUpdate(tCar *car, tWheel *wheel, tBrake *brake)
{
    brake->Tq = brake->coeff * brake->pressure;

    const tdble cooling = ((tdble) fabs(car->DynGC.vel.x) * 0.02f + 0.1f) * SimDeltaTime;
    brake->temp -= cooling;
    if (brake->temp < 0 ) brake->temp = 0;
    const tdble heating = (brake->pressure * brake->radius * (tdble) fabs(wheel->spinVel) * 2.5e-8f) * SimDeltaTime;
    brake->temp += heating;
    if (brake->temp > 1.0) brake->temp = 1.0;
}


void SimBrakeSystemConfig(tCar *car)
{
    void *hdle = car->params;

    car->brkSyst.rep   = GfParmGetNum(hdle, SECT_BRKSYST, PRM_BRKREP, (char*)NULL, 0.5f);
    car->brkSyst.coeff = GfParmGetNum(hdle, SECT_BRKSYST, PRM_BRKPRESS, (char*)NULL, 1000000);
    car->brkSyst.repCmdClickValue = GfParmGetNum(hdle, SECT_BRKSYST, PRM_BRKREPCMD_CLICKVALUE, (char*)NULL, 0.0025f);
    car->brkSyst.repCmdMaxClicks = (int) GfParmGetNum(hdle, SECT_BRKSYST, PRM_BRKREPCMD_MAXCLICKS, (char*)NULL, 20);
}


void SimBrakeSystemReConfig(tCar *car)
{
    tCarPitSetupValue* v = &car->carElt->pitcmd.setup.brakeRepartition;
    if (SimAdjustPitCarSetupParam(v)) {
        car->brkSyst.rep = v->value;
    }

    v = &car->carElt->pitcmd.setup.brakePressure;
    if (SimAdjustPitCarSetupParam(v)) {
        car->brkSyst.coeff = v->value;
    }
}


void SimBrakeSystemUpdate(tCar *car)
{
    tBrakeSyst  *brkSyst = &(car->brkSyst);
    tdble   ctrl = car->ctrl->brakeCmd;
    int brakeRepartitionCmd = car->ctrl->brakeRepartitionCmd;

    // Check boundaries of allowed adjustment, adjust if out of bounds
    if (brakeRepartitionCmd > brkSyst->repCmdMaxClicks) {
        brakeRepartitionCmd = brkSyst->repCmdMaxClicks;
    } else if (brakeRepartitionCmd < -brkSyst->repCmdMaxClicks) {
        brakeRepartitionCmd = -brkSyst->repCmdMaxClicks;
    }

    // Calculate effective brake repartition considering the driver input, checking boundaries of final repartition
    tdble repartition = brkSyst->rep + brakeRepartitionCmd*car->brkSyst.repCmdClickValue;
    if (repartition > 1.0) {
        repartition = 1.0;
    } else if (repartition < 0.0) {
        repartition = 0.0;
    }

    ctrl *= brkSyst->coeff;
    car->wheel[FRNT_RGT].brake.pressure = car->wheel[FRNT_LFT].brake.pressure = ctrl * repartition;
    car->wheel[REAR_RGT].brake.pressure = car->wheel[REAR_LFT].brake.pressure = ctrl * (1 - repartition);
}