flightgear/src/AIModel/performancedata.cxx

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "performancedata.hxx"
#include "AIAircraft.hxx"


// For now, make this a define
// Later on, additional class variables can simulate settings such as braking power
// also, the performance parameters can be tweaked a little to add some personality
// to the AIAircraft.
#define BRAKE_SETTING 1.6

PerformanceData::PerformanceData(double acceleration,
                                double deceleration,
                                double climbRate,
                                double descentRate,
                                double vRotate,
                                double vTakeOff,
                                double vClimb,
                                double vCruise,
                                double vDescent,
                                double vApproach,
                                double vTouchdown,
                                double vTaxi) :
    _acceleration(acceleration),
    _deceleration(deceleration),
    _climbRate(climbRate),
    _descentRate(descentRate),
    _vRotate(vRotate),
    _vTakeOff(vTakeOff),
    _vClimb(vClimb),
    _vCruise(vCruise),
    _vDescent(vDescent),
    _vApproach(vApproach),
    _vTouchdown(vTouchdown),
    _vTaxi(vTaxi)
{
    _rollrate = 9.0; // degrees per second
    _maxbank = 30.0; // passenger friendly bank angle
}

// read perf data from file
PerformanceData::PerformanceData( const std::string& filename)
{}

PerformanceData::~PerformanceData()
{}

double PerformanceData::actualSpeed(FGAIAircraft* ac, double tgt_speed, double dt, bool maxBrakes) {
    // if (tgt_speed > _vTaxi & ac->onGround()) // maximum taxi speed on ground
    //    tgt_speed = _vTaxi;
    // bad idea for a take off roll :-)

    double speed = ac->getSpeed();
    double speed_diff = tgt_speed - speed;

    if (speed_diff > 0.0)        // need to accelerate
    {
        speed += _acceleration * dt;
        if ( speed > tgt_speed )
            speed = tgt_speed;

    } else if (speed_diff < 0.0) { // decelerate
        if (ac->onGround()) {
            // deceleration performance is better due to wheel brakes.
            double brakePower = 0;
            if (maxBrakes) {
                brakePower = 3;
            } else {
                brakePower = BRAKE_SETTING;
            }
            speed -= brakePower * _deceleration * dt;
        } else {
            speed -= _deceleration * dt;
        }

        if ( speed < tgt_speed )
            speed = tgt_speed;

    }

    return speed;
}

double PerformanceData::actualBankAngle(FGAIAircraft* ac, double tgt_roll, double dt) {
    // check maximum bank angle
    if (fabs(tgt_roll) > _maxbank)
        tgt_roll = _maxbank * tgt_roll/fabs(tgt_roll);

    double roll = ac->getRoll();
    double bank_diff = tgt_roll - roll;

    if (fabs(bank_diff) > 0.2) {
        if (bank_diff > 0.0) {
            roll += _rollrate * dt;
            if (roll > tgt_roll)
                roll = tgt_roll;
        }
        else if (bank_diff < 0.0) {
            roll -= _rollrate * dt;

            if (roll < tgt_roll)
                roll = tgt_roll;
        }
        //while (roll > 180) roll -= 360;
        //while (roll < 180) roll += 360;
    }

    return roll;
}

double PerformanceData::actualPitch(FGAIAircraft* ac, double tgt_pitch, double dt) {
    double pitch = ac->getPitch();
    double pdiff = tgt_pitch - pitch;

    if (pdiff > 0.0) { // nose up
        pitch += 0.005*_climbRate * dt / 3.0; //TODO avoid hardcoded 3 secs

        if (pitch > tgt_pitch)
            pitch = tgt_pitch;
    } else if (pdiff < 0.0) { // nose down
        pitch -= 0.002*_descentRate * dt / 3.0;

        if (pitch < tgt_pitch)
            pitch = tgt_pitch;
    }

    return pitch;
}

double PerformanceData::actualAltitude(FGAIAircraft* ac, double tgt_altitude, double dt) {
    if (ac->onGround()) {
        //FIXME: a return sensible value here
        return 0.0; // 0 for now to avoid compiler errors
    } else
        return ac->getAltitude() + ac->getVerticalSpeed()*dt/60.0;
}

double PerformanceData::actualVerticalSpeed(FGAIAircraft* ac, double tgt_vs, double dt) {
    double vs = ac->getVerticalSpeed();
    double vs_diff = tgt_vs - vs;

    if (fabs(vs_diff) > .001) {
        if (vs_diff > 0.0) {
            vs += _climbRate * dt / 3.0; //TODO avoid hardcoded 3 secs to attain climb rate from level flight

            if (vs > tgt_vs)
                vs = tgt_vs;
        } else if (vs_diff < 0.0) {
            vs -= _descentRate * dt / 3.0;

            if (vs < tgt_vs)
                vs = tgt_vs;
        }
    }

    return vs;
}

bool PerformanceData::gearExtensible(const FGAIAircraft* ac) {
    return (ac->altitudeAGL() < 900.0)
            && (ac->airspeed() < _vTouchdown * 1.25);
}