performancedata.cxx

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#include "config.h"
 
 
 
#include <simgear/props/props.hxx>
 
#include "AIAircraft.hxx"
 
#include "performancedata.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::getDefaultData()
{
    static PerformanceData static_instance;
    return &static_instance;
}
 
PerformanceData::PerformanceData() : _acceleration(4.0),
                                     _deceleration(2.0),
                                     _brakeDeceleration(20.0),
                                     _climbRate(3000.0),
                                     _descentRate(1500.0),
                                     _vRotate(150.0),
                                     _vTakeOff(160.0),
                                     _vClimb(300.0),
                                     _vCruise(430.0),
                                     _vDescent(300.0),
                                     _vApproach(170.0),
                                     _vTouchdown(150.0),
                                     _vTaxi(15.0),
                                     _wingSpan(100.0),
                                     _wingChord(12.0),
                                     _weight(90000.0)
{
    _rollrate = 9.0; // degrees per second
    _maxbank = 30.0; // passenger friendly bank angle
}
 
PerformanceData::PerformanceData(const PerformanceData* clone) : _acceleration(clone->_acceleration),
                                                                 _deceleration(clone->_deceleration),
                                                                 _brakeDeceleration(clone->_brakeDeceleration),
                                                                 _climbRate(clone->_climbRate),
                                                                 _descentRate(clone->_descentRate),
                                                                 _vRotate(clone->_vRotate),
                                                                 _vTakeOff(clone->_vTakeOff),
                                                                 _vClimb(clone->_vClimb),
                                                                 _vCruise(clone->_vCruise),
                                                                 _vDescent(clone->_vDescent),
                                                                 _vApproach(clone->_vApproach),
                                                                 _vTouchdown(clone->_vTouchdown),
                                                                 _vTaxi(clone->_vTaxi),
                                                                 _wingSpan(clone->_wingSpan),
                                                                 _wingChord(clone->_wingChord),
                                                                 _weight(clone->_weight)
{
    _rollrate = clone->_rollrate;
    _maxbank = clone->_maxbank;
}
 
// helper to try various names of a property, in order.
static double readRenamedProp(SGPropertyNode_ptr db, const string_list& namesToTry, double defValue)
{
    for (const auto& n : namesToTry) {
        auto node = db->getChild(n);
        if (node) {
            return node->getDoubleValue();
        }
    }
 
    return defValue;
}
 
void PerformanceData::initFromProps(SGPropertyNode* db_node)
{
    // read the values, using the existing values as defaults
    _acceleration = db_node->getDoubleValue("acceleration-kts-hour", _acceleration);
    _deceleration = db_node->getDoubleValue("deceleration-kts-hour", _deceleration);
    _brakeDeceleration = db_node->getDoubleValue("brake-deceleration-kts-hour", _brakeDeceleration);
 
    _climbRate = readRenamedProp(db_node, {"climb-rate-fpm", "climbrate-fpm"}, _climbRate);
    _descentRate = readRenamedProp(db_node, {"descent-rate-fpm", "decentrate-fpm"}, _descentRate);
 
    _vRotate = db_node->getDoubleValue("rotate-speed-kts", _vRotate);
    _vTakeOff = db_node->getDoubleValue("takeoff-speed-kts", _vTakeOff);
    _vClimb = db_node->getDoubleValue("climb-speed-kts", _vClimb);
    _vCruise = db_node->getDoubleValue("cruise-speed-kts", _vCruise);
 
    _vDescent = readRenamedProp(db_node, {"descent-speed-kts", "decent-speed-kts"}, _vDescent);
 
    _vApproach = db_node->getDoubleValue("approach-speed-kts", _vApproach);
    _vTouchdown = db_node->getDoubleValue("touchdown-speed-kts", _vTouchdown);
    _vTaxi = db_node->getDoubleValue("taxi-speed-kts", _vTaxi);
    _wingSpan = db_node->getDoubleValue("geometry/wing/span-ft", _wingSpan);
    _wingChord = db_node->getDoubleValue("geometry/wing/chord-ft", _wingChord);
    _weight = db_node->getDoubleValue("geometry/weight-lbs", _weight);
}
 
double PerformanceData::actualSpeed(const 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 = 2;
            } else {
                brakePower = 1;
            }
            speed -= brakePower * _brakeDeceleration * dt;
        } else {
            speed -= _deceleration * dt;
        }
 
        if (speed < tgt_speed)
            speed = tgt_speed;
    }
 
    return speed;
}
 
double PerformanceData::decelerationOnGround() const
{
    return _brakeDeceleration;
}
 
double PerformanceData::actualBankAngle(const 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(const 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(const 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->getVerticalSpeedFPM() * dt / 60.0;
}
 
double PerformanceData::actualVerticalSpeed(const FGAIAircraft* ac, double tgt_vs, double dt)
{
    double vs = ac->getVerticalSpeedFPM();
    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);
}