flightgear/src/AIModel/AIMultiplayer.cxx

// FGAIMultiplayer - FGAIBase-derived class creates an AI multiplayer aircraft
//
// Based on FGAIAircraft
// Written by David Culp, started October 2003.
// Also by Gregor Richards, started December 2005.
//
// Copyright (C) 2003  David P. Culp - davidculp2@comcast.net
// Copyright (C) 2005  Gregor Richards
//
// 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.
//
// 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, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <string>

#include "AIMultiplayer.hxx"


// #define SG_DEBUG SG_ALERT

FGAIMultiplayer::FGAIMultiplayer() :
   FGAIBase(otMultiplayer, false)
{
   no_roll = false;

   mTimeOffsetSet = false;
   mAllowExtrapolation = true;
   mLagAdjustSystemSpeed = 10;
   mLastTimestamp = 0;
   lastUpdateTime = 0;

} 

FGAIMultiplayer::~FGAIMultiplayer() {
}

bool FGAIMultiplayer::init(bool search_in_AI_path) {
    props->setStringValue("sim/model/path", model_path.c_str());
    //refuel_node = fgGetNode("systems/refuel/contact", true);
    isTanker = false; // do this until this property is
                      // passed over the net

    string str1 = _getCallsign();
    string str2 = "MOBIL";

    string::size_type loc1= str1.find( str2, 0 );
    if ( (loc1 != string::npos && str2 != "") ){
        //	   cout << " string found "	<< str2 << " in " << str1 << endl;
        isTanker = true;
        //	   cout << "isTanker " << isTanker << " " << mCallSign <<endl;
    }

    // load model
    bool result = FGAIBase::init(search_in_AI_path);
    // propagate installation state (used by MP pilot list)
    props->setBoolValue("model-installed", _installed);
    return result;
}

void FGAIMultiplayer::bind() {
    FGAIBase::bind();

    tie("refuel/contact", SGRawValuePointer<bool>(&contact));
    tie("tanker", SGRawValuePointer<bool>(&isTanker));

    tie("controls/invisible",
        SGRawValuePointer<bool>(&invisible));

#define AIMPROProp(type, name) \
SGRawValueMethods<FGAIMultiplayer, type>(*this, &FGAIMultiplayer::get##name)

#define AIMPRWProp(type, name) \
SGRawValueMethods<FGAIMultiplayer, type>(*this, \
      &FGAIMultiplayer::get##name, &FGAIMultiplayer::set##name)

    //tie("callsign", AIMPROProp(const char *, CallSign));

    tie("controls/allow-extrapolation",
        AIMPRWProp(bool, AllowExtrapolation));
    tie("controls/lag-adjust-system-speed",
        AIMPRWProp(double, LagAdjustSystemSpeed));


#undef AIMPROProp
#undef AIMPRWProp
}

void FGAIMultiplayer::update(double dt)
{
  using namespace simgear;

  if (dt <= 0)
    return;

  FGAIBase::update(dt);

  // Check if we already got data
  if (mMotionInfo.empty())
    return;

  // The current simulation time we need to update for,
  // note that the simulation time is updated before calling all the
  // update methods. Thus it contains the time intervals *end* time
  double curtime = globals->get_sim_time_sec();

  // Get the last available time
  MotionInfo::reverse_iterator it = mMotionInfo.rbegin();
  double curentPkgTime = it->second.time;

  // Dynamically optimize the time offset between the feeder and the client
  // Well, 'dynamically' means that the dynamic of that update must be very
  // slow. You would otherwise notice huge jumps in the multiplayer models.
  // The reason is that we want to avoid huge extrapolation times since
  // extrapolation is highly error prone. For that we need something
  // approaching the average latency of the packets. This first order lag
  // component will provide this. We just take the error of the currently
  // requested time to the most recent available packet. This is the
  // target we want to reach in average.
  double lag = it->second.lag;
  if (!mTimeOffsetSet) {
    mTimeOffsetSet = true;
    mTimeOffset = curentPkgTime - curtime - lag;
  } else {
    double offset = curentPkgTime - curtime - lag;
    if ((!mAllowExtrapolation && offset + lag < mTimeOffset)
        || (offset - 10 > mTimeOffset)) {
      mTimeOffset = offset;
      SG_LOG(SG_AI, SG_DEBUG, "Resetting time offset adjust system to "
             "avoid extrapolation: time offset = " << mTimeOffset);
    } else {
      // the error of the offset, respectively the negative error to avoid
      // a minus later ...
      double err = offset - mTimeOffset;
      // limit errors leading to shorter lag values somehow, that is late
      // arriving packets will pessimize the overall lag much more than
      // early packets will shorten the overall lag
      double sysSpeed;
      if (err < 0) {
        // Ok, we have some very late packets and nothing newer increase the
        // lag by the given speedadjust
        sysSpeed = mLagAdjustSystemSpeed*err;
      } else {
        // We have a too pessimistic display delay shorten that a small bit
        sysSpeed = SGMiscd::min(0.1*err*err, 0.5);
      }

      // simple euler integration for that first order system including some
      // overshooting guard to prevent to aggressive system speeds
      // (stiff systems) to explode the systems state
      double systemIncrement = dt*sysSpeed;
      if (fabs(err) < fabs(systemIncrement))
        systemIncrement = err;
      mTimeOffset += systemIncrement;
      
      SG_LOG(SG_AI, SG_DEBUG, "Offset adjust system: time offset = "
             << mTimeOffset << ", expected longitudinal position error due to "
             " current adjustment of the offset: "
             << fabs(norm(it->second.linearVel)*systemIncrement));
    }
  }


  // Compute the time in the feeders time scale which fits the current time
  // we need to 
  double tInterp = curtime + mTimeOffset;

  SGVec3d ecPos;
  SGQuatf ecOrient;

  if (tInterp <= curentPkgTime) {
    // Ok, we need a time prevous to the last available packet,
    // that is good ...

    // Find the first packet before the target time
    MotionInfo::iterator nextIt = mMotionInfo.upper_bound(tInterp);
    if (nextIt == mMotionInfo.begin()) {
      SG_LOG(SG_AI, SG_DEBUG, "Taking oldest packet!");
      // We have no packet before the target time, just use the first one
      MotionInfo::iterator firstIt = mMotionInfo.begin();
      ecPos = firstIt->second.position;
      ecOrient = firstIt->second.orientation;
      speed = norm(firstIt->second.linearVel) * SG_METER_TO_NM * 3600.0;

      std::vector<FGPropertyData*>::const_iterator firstPropIt;
      std::vector<FGPropertyData*>::const_iterator firstPropItEnd;
      firstPropIt = firstIt->second.properties.begin();
      firstPropItEnd = firstIt->second.properties.end();
      while (firstPropIt != firstPropItEnd) {
        //cout << " Setting property..." << (*firstPropIt)->id;
        PropertyMap::iterator pIt = mPropertyMap.find((*firstPropIt)->id);
        if (pIt != mPropertyMap.end())
        {
          //cout << "Found " << pIt->second->getPath() << ":";
          switch ((*firstPropIt)->type) {
            case props::INT:
            case props::BOOL:
            case props::LONG:
              pIt->second->setIntValue((*firstPropIt)->int_value);
              //cout << "Int: " << (*firstPropIt)->int_value << "\n";
              break;
            case props::FLOAT:
            case props::DOUBLE:
              pIt->second->setFloatValue((*firstPropIt)->float_value);
              //cout << "Flo: " << (*firstPropIt)->float_value << "\n";
              break;
            case props::STRING:
            case props::UNSPECIFIED:
              pIt->second->setStringValue((*firstPropIt)->string_value);
              //cout << "Str: " << (*firstPropIt)->string_value << "\n";    
              break;
            default:
              // FIXME - currently defaults to float values
              pIt->second->setFloatValue((*firstPropIt)->float_value);
              //cout << "Unknown: " << (*firstPropIt)->float_value << "\n";
              break;
          }            
        }
        else
        {
          SG_LOG(SG_AI, SG_DEBUG, "Unable to find property: " << (*firstPropIt)->id << "\n");
        }
        ++firstPropIt;
      }

    } else {
      // Ok, we have really found something where our target time is in between
      // do interpolation here
      MotionInfo::iterator prevIt = nextIt;
      --prevIt;

      // Interpolation coefficient is between 0 and 1
      double intervalStart = prevIt->second.time;
      double intervalEnd = nextIt->second.time;
      double intervalLen = intervalEnd - intervalStart;
      double tau = (tInterp - intervalStart)/intervalLen;

      SG_LOG(SG_AI, SG_DEBUG, "Multiplayer vehicle interpolation: ["
             << intervalStart << ", " << intervalEnd << "], intervalLen = "
             << intervalLen << ", interpolation parameter = " << tau);

      // Here we do just linear interpolation on the position
      ecPos = ((1-tau)*prevIt->second.position + tau*nextIt->second.position);
      ecOrient = interpolate((float)tau, prevIt->second.orientation,
                             nextIt->second.orientation);
      speed = norm((1-tau)*prevIt->second.linearVel
                   + tau*nextIt->second.linearVel) * SG_METER_TO_NM * 3600.0;

      if (prevIt->second.properties.size()
          == nextIt->second.properties.size()) {
        std::vector<FGPropertyData*>::const_iterator prevPropIt;
        std::vector<FGPropertyData*>::const_iterator prevPropItEnd;
        std::vector<FGPropertyData*>::const_iterator nextPropIt;
        std::vector<FGPropertyData*>::const_iterator nextPropItEnd;
        prevPropIt = prevIt->second.properties.begin();
        prevPropItEnd = prevIt->second.properties.end();
        nextPropIt = nextIt->second.properties.begin();
        nextPropItEnd = nextIt->second.properties.end();
        while (prevPropIt != prevPropItEnd) {
          PropertyMap::iterator pIt = mPropertyMap.find((*prevPropIt)->id);
          //cout << " Setting property..." << (*prevPropIt)->id;
          
          if (pIt != mPropertyMap.end())
          {
            //cout << "Found " << pIt->second->getPath() << ":";
          
            int ival;
            float val;
            switch ((*prevPropIt)->type) {
              case props::INT:
              case props::BOOL:
              case props::LONG:
                ival = (int) (0.5+(1-tau)*((double) (*prevPropIt)->int_value) +
                  tau*((double) (*nextPropIt)->int_value));
                pIt->second->setIntValue(ival);
                //cout << "Int: " << ival << "\n";
                break;
              case props::FLOAT:
              case props::DOUBLE:
                val = (1-tau)*(*prevPropIt)->float_value +
                  tau*(*nextPropIt)->float_value;
                //cout << "Flo: " << val << "\n";
                pIt->second->setFloatValue(val);
                break;
              case props::STRING:
              case props::UNSPECIFIED:
                //cout << "Str: " << (*nextPropIt)->string_value << "\n";
                pIt->second->setStringValue((*nextPropIt)->string_value);
                break;
              default:
                // FIXME - currently defaults to float values
                val = (1-tau)*(*prevPropIt)->float_value +
                  tau*(*nextPropIt)->float_value;
                //cout << "Unk: " << val << "\n";
                pIt->second->setFloatValue(val);
                break;
            }            
          }
          else
          {
            SG_LOG(SG_AI, SG_DEBUG, "Unable to find property: " << (*prevPropIt)->id << "\n");
          }
          
          ++prevPropIt;
          ++nextPropIt;
        }
      }

      // Now throw away too old data
      if (prevIt != mMotionInfo.begin()) 
      {
        --prevIt;
        mMotionInfo.erase(mMotionInfo.begin(), prevIt);
      }
    }
  } else {
    // Ok, we need to predict the future, so, take the best data we can have
    // and do some eom computation to guess that for now.
    FGExternalMotionData& motionInfo = it->second;

    // The time to predict, limit to 5 seconds
    double t = tInterp - motionInfo.time;
    t = SGMisc<double>::min(t, 5);

    SG_LOG(SG_AI, SG_DEBUG, "Multiplayer vehicle extrapolation: "
           "extrapolation time = " << t);

    // Do a few explicit euler steps with the constant acceleration's
    // This must be sufficient ...
    ecPos = motionInfo.position;
    ecOrient = motionInfo.orientation;
    SGVec3f linearVel = motionInfo.linearVel;
    SGVec3f angularVel = motionInfo.angularVel;
    while (0 < t) {
      double h = 1e-1;
      if (t < h)
        h = t;

      SGVec3d ecVel = toVec3d(ecOrient.backTransform(linearVel));
      ecPos += h*ecVel;
      ecOrient += h*ecOrient.derivative(angularVel);

      linearVel += h*(cross(linearVel, angularVel) + motionInfo.linearAccel);
      angularVel += h*motionInfo.angularAccel;
      
      t -= h;
    }

    std::vector<FGPropertyData*>::const_iterator firstPropIt;
    std::vector<FGPropertyData*>::const_iterator firstPropItEnd;
    speed = norm(linearVel) * SG_METER_TO_NM * 3600.0;
    firstPropIt = it->second.properties.begin();
    firstPropItEnd = it->second.properties.end();
    while (firstPropIt != firstPropItEnd) {
      PropertyMap::iterator pIt = mPropertyMap.find((*firstPropIt)->id);
      //cout << " Setting property..." << (*firstPropIt)->id;
      
      if (pIt != mPropertyMap.end())
      {
        switch ((*firstPropIt)->type) {
          case props::INT:
          case props::BOOL:
          case props::LONG:
            pIt->second->setIntValue((*firstPropIt)->int_value);
            //cout << "Int: " << (*firstPropIt)->int_value << "\n";
            break;
          case props::FLOAT:
          case props::DOUBLE:
            pIt->second->setFloatValue((*firstPropIt)->float_value);
            //cout << "Flo: " << (*firstPropIt)->float_value << "\n";
            break;
          case props::STRING:
          case props::UNSPECIFIED:
            pIt->second->setStringValue((*firstPropIt)->string_value);
            //cout << "Str: " << (*firstPropIt)->string_value << "\n";
            break;
          default:
            // FIXME - currently defaults to float values
            pIt->second->setFloatValue((*firstPropIt)->float_value);
            //cout << "Unk: " << (*firstPropIt)->float_value << "\n";
            break;
        }            
      }
      else
      {
        SG_LOG(SG_AI, SG_DEBUG, "Unable to find property: " << (*firstPropIt)->id << "\n");
      }
      
      ++firstPropIt;
    }
  }
  
  // extract the position
  pos = SGGeod::fromCart(ecPos);
  double recent_alt_ft = altitude_ft;
  altitude_ft = pos.getElevationFt();

  // expose a valid vertical speed
  if (lastUpdateTime != 0)
  {
      double dT = curtime - lastUpdateTime;
      double Weighting=1;
      if (dt < 1.0)
          Weighting = dt;
      // simple smoothing over 1 second
      vs = (1.0-Weighting)*vs +  Weighting * (altitude_ft - recent_alt_ft) / dT * 60;
  }
  lastUpdateTime = curtime;

  // The quaternion rotating from the earth centered frame to the
  // horizontal local frame
  SGQuatf qEc2Hl = SGQuatf::fromLonLatRad((float)pos.getLongitudeRad(),
                                          (float)pos.getLatitudeRad());
  // The orientation wrt the horizontal local frame
  SGQuatf hlOr = conj(qEc2Hl)*ecOrient;
  float hDeg, pDeg, rDeg;
  hlOr.getEulerDeg(hDeg, pDeg, rDeg);
  hdg = hDeg;
  roll = rDeg;
  pitch = pDeg;

  SG_LOG(SG_AI, SG_DEBUG, "Multiplayer position and orientation: "
         << ecPos << ", " << hlOr);

  //###########################//
  // do calculations for radar //
  //###########################//
    double range_ft2 = UpdateRadar(manager);

    //************************************//
    // Tanker code                        //
    //************************************//


    if ( isTanker) {
        //cout << "IS tanker ";
        if ( (range_ft2 < 250.0 * 250.0) &&
            (y_shift > 0.0)    &&
            (elevation > 0.0) ){
                // refuel_node->setBoolValue(true);
                 //cout << "in contact"  << endl;
            contact = true;
        } else {
            // refuel_node->setBoolValue(false);
            //cout << "not in contact"  << endl;
            contact = false;
        }
    } else {
        //cout << "NOT tanker " << endl;
        contact = false;
    }

  Transform();
}

void
FGAIMultiplayer::addMotionInfo(FGExternalMotionData& motionInfo,
                               long stamp)
{
  mLastTimestamp = stamp;

  if (!mMotionInfo.empty()) {
    double diff = motionInfo.time - mMotionInfo.rbegin()->first;

    // packet is very old -- MP has probably reset (incl. his timebase)
    if (diff < -10.0)
      mMotionInfo.clear();

    // drop packets arriving out of order
    else if (diff < 0.0)
      return;
  }
  mMotionInfo[motionInfo.time] = motionInfo;
  // We just copied the property (pointer) list - they are ours now. Clear the
  // properties list in given/returned object, so former owner won't deallocate them.
  motionInfo.properties.clear();
}

void
FGAIMultiplayer::setDoubleProperty(const std::string& prop, double val)
{
  SGPropertyNode* pNode = props->getChild(prop.c_str(), true);
  pNode->setDoubleValue(val);
}