MySignaturePropagator

Header File:

Implementation

/*******************************************************************************
** Copyright (c) 2022 MAK Technologies, Inc.
** All rights reserved.
*******************************************************************************/

#include "mySignaturePropagator.h"
#include "vrfobjcore/signaturePropagatorArgs.h"
#include "vrfobjcore/vrfObjectStateRepository.h"
#include "vrfobjcore/physicalWorld.h"
#include "terrainInterface/terrainInterface.h"
#include "features/areaFeature.h"
#include "features/featureGeometry.h"

// This local exception insures that only the code in this class will ever catch
// this exception. It's thrown as soon as FindOneFeature finds something.
struct ExitSearchException{};

// Used as the functor passed into DtAreaFeatureSet::forEachFeature to 
// see if there's at least one hit. When one is found ExitSearchException is
// thrown to prevent any unnecessary searching.
struct FindOneFeature
{
   FindOneFeature() { }

   void operator()(const MAKVRinTerra::DtAreaFeature& feature)
   {
      throw ExitSearchException();
   }
};


// default constructor
MySignaturePropagator::MySignaturePropagator(
   const DtSignaturePropagatorDescriptor* desc, DtPhysicalWorld* physicalWorld) 
   : DtVisualSignaturePropagator(desc, physicalWorld)
{
}

// destructor
MySignaturePropagator::~MySignaturePropagator()
{
}

void MySignaturePropagator::init()
{
   DtVisualSignaturePropagator::init();
}

double MySignaturePropagator::calculateApparentSignature(
   double absoluteSignature, const DtSignaturePropagatorArgs& args, bool* dataAvailable) const
{
   //Get the apparent signature from the parent class.  This will include
   //terrain blockage tests, weather visibility effects, and tactical smoke 
   //blockage.
   double apparentSig = DtVisualSignaturePropagator::calculateApparentSignature(
      absoluteSignature, args, dataAvailable);
   //This is an optimization.  The minSignatureThreshold() value is set by the 
   //sensor calling this propagator, and indicates the smallest returned value
   //that it will care about.  Any value smaller than this is the same as 0
   //to the caller.
   //So, if the apparentSig is already less than this value, the additional checks
   //can be skipped, as long as those checks can only reduce the value further.
   if (apparentSig < args.minSignatureThreshold())
   {
      return 0;
   }
   
   using namespace MAKVRinTerra;

   //Get the area feature set that matches the query "FOREST".
   //See appData/settings/featureconfig.txt for the named feature types
   //and their definitions.
   std::auto_ptr<MAKVRinTerra::DtAreaFeatureSet> losFeatures = 
      myPhysicalWorld->terrainInterface()->areas("FOREST");

   if (!losFeatures.get())
   {
      losFeatures.reset(new DtAreaFeatureSet::Empty());
   }

   //Feature queries use DtFeatureGeometry objects for determining 
   //geometric intersections.
   //Create a point feature geometry using the target's position and 
   //the local proj object.
   DtVector targetPosition = args.targetObject()->localPosition();
   DtProj::CPtr localProj = myPhysicalWorld->terrainInterface()->localProj();
   DtFeatureGeometry targetPoint = 
      DtFeatureGeometry::Point::Make(targetPosition, *localProj);

   //Construct a feature query for all areal features that intersect target point
   //The area feature set that matches FOREST can contain areal, 
   //point, or linear features, so our query specifies areal features.
   DtQuery areaTypeQuery = DtHasGeometry::Create(DtFeatureGeometry::AreaType);

   //Filter the feature set using our query.  Pass the LOAD flag so 
   //this filtering will cause features to be loaded in the background.
   //This loading will continue regardless of what happens to the local
   //objects "losFeatures" and "areas", meaning subsequent calls will
   //have the features already loaded.
   std::auto_ptr<DtAreaFeatureSet> obstacles(
      losFeatures->filter(areaTypeQuery, targetPoint, LOAD));

   // See if there's at least one feature in the set. See the definitions of
   // FindOneFeature and ExitSearchException above.
   if (obstacles.get())
   {
      try 
      {
         FindOneFeature finder;
         obstacles->forEachFeature(boost::ref(finder));
      }
      catch (ExitSearchException)
      {
         DtInfo << "Target " << args.targetObject()->objectName()
            << " is in an area.  Cutting apparent signature in half." << std::endl;
         return apparentSig / 2.0;
      }
   }

   return apparentSig;
}

//This is the static creator method that is registered with the factory.
DtSignaturePropagator* MySignaturePropagator::create(
   const DtSignaturePropagatorDescriptor* desc, DtPhysicalWorld* physicalWorld)
{
   DtSignaturePropagator* prop = new MySignaturePropagator(desc, physicalWorld);
   prop->init();
   return prop;
}