axle.cpp

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

    file                 : axle.cpp
    created              : Sun Mar 19 00:05:09 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"

static const char *AxleSect[2] = {SECT_FRNTAXLE, SECT_REARAXLE};

void SimAxleConfig(tCar *car, int index)
{
    void    *hdle = car->params;
    tdble   rollCenter;
    
    tAxle *axle = &(car->axle[index]);
    
    axle->xpos = GfParmGetNum(hdle, AxleSect[index], PRM_XPOS, (char*)NULL, 0.0f);
    axle->I    = GfParmGetNum(hdle, AxleSect[index], PRM_INERTIA, (char*)NULL, 0.15f);
    rollCenter = GfParmGetNum(hdle, AxleSect[index], PRM_ROLLCENTER, (char*)NULL, 0.15f);
    car->wheel[index*2].rollCenter = car->wheel[index*2+1].rollCenter = rollCenter;
    
    tdble x0 = GfParmGetNum(hdle, AxleSect[index], PRM_SUSPCOURSE, (char*)NULL, 0.0f);
    SimSuspConfig(hdle, AxleSect[index], &(axle->thirdSusp), 0.0f, x0);

    if (index == 0) {
        axle->arbSuspSpringK = GfParmGetNum(hdle, SECT_FRNTARB, PRM_SPR, (char*)NULL, 0.0f);
    } else {
        axle->arbSuspSpringK = GfParmGetNum(hdle, SECT_REARARB, PRM_SPR, (char*)NULL, 0.0f);
    }
    
    car->wheel[index*2].feedBack.I += axle->I / 2.0f;
    car->wheel[index*2+1].feedBack.I += axle->I / 2.0f;
}


void SimAxleReConfig(tCar *car, int index)
{
    tAxle *axle = &(car->axle[index]);

    // Anti rollbar spring
    tCarPitSetupValue* v = &car->carElt->pitcmd.setup.arbspring[index];
    if (SimAdjustPitCarSetupParam(v)) {
        axle->arbSuspSpringK = v->value;
    }

    // Third element
    v = &car->carElt->pitcmd.setup.thirdX0[index];
    SimAdjustPitCarSetupParam(v);
    SimSuspThirdReConfig(car, index, &(axle->thirdSusp), 0.0f, v->value);
}


void SimAxleUpdate(tCar *car, int index)
{
    tAxle *axle = &(car->axle[index]);
    tdble str, stl, vr, vl;
    
    str = car->wheel[index*2].susp.x;
    stl = car->wheel[index*2+1].susp.x;
    vr = car->wheel[index*2].susp.v;
    vl = car->wheel[index*2+1].susp.v;
    
    // Anti roll bar
    tdble farb = axle->arbSuspSpringK * (stl - str);

    // Third element
    axle->thirdSusp.x = (stl + str)/2.0f;
    axle->thirdSusp.v = (vl + vr)/2.0f;
    SimSuspUpdate(&axle->thirdSusp);
    tdble fthird = 0.0f;
    if (axle->thirdSusp.x < axle->thirdSusp.spring.xMax && axle->thirdSusp.force > 0.0f) {
        fthird = axle->thirdSusp.force/2.0f;
    }

    // right
    car->wheel[index*2].axleFz = farb + fthird;
    // left
    car->wheel[index*2+1].axleFz = -farb + fthird;
}