Articulated Parts Example

Table of Contents

• Implementing Articulated Parts
• Example Code

The code to manipulate articulated parts was re-written for VR-Link 3.12.

All classes were written to maintain backwards compatibility, while at the same time providing a robust and intuitive interface to access articulated parts.

Implementing Articulated Parts

Articulated parts are implemented in two classes:

• DtArticulatedPartCollection The container used to store Articulated Parts.
• DtArticulatedPart The representation of an articulated part. DtArticulatedPart are a container of Articulated Parameters.

Other examples which use articulated parts include:

• The F18 simulator example

Example Code

A typical usage of articulated parts may look like this:

// Required header for all entities
#include <vl/entityStateRepository.h>

// The following headers are actually already included
// in entitySR.h, but are included here for reference.
#include <vlpi/articulatedPartCollection.h>
#include <vlpi/articulatedPart.h>

// Used for DtInfo in this example
#include <vlutil/vlPrint.h>


// This function passes the classes which are needed for Articulated Parts...
void artPartsExample(DtEntityStateRepository *anEntity)
{
   DtArticulatedPartCollection* artPartCol = anEntity->artPartList();

   // Here we set some Articulated Parts: A gun with elevation and a turrent with azimuth and rate.
   
   // The Articulated part collection is a map of DtArticulatedParts keyed to the PartType.
   // Note that the part type is in fact an integer, but normally under DIS 
   // you would want the value to be one of the defined enumerations
   // DtArtPartType and DtArtParamType.
   // Note that the getPart() method of DtArticulatedPartCollection will create
   // an articulated part of the specified part type, if it does not exist.
   DtArticulatedPart& turret = artPartCol->getPart(DtPrimaryTurret1);
   DtArticulatedPart& gun = artPartCol->getPart(DtPrimaryGun1);
   turret.setParameter(DtApAzimuth, 3.14f);
   turret.setParameter(DtApAzimuthRate, 3.14f);
   gun.setParameter(DtApElevation, 3.14f);

   // Now, we attach the gun to the turret.  By default, parts are attached to the 
   // entity when created.
   artPartCol->attachPart(&gun, &turret);

   // Read and print all of the articulated parts and parameters.
   // The first loop iterates through the known collections of articulated parts.
   for(DtArticulatedPartCollection::const_iterator artPartIter = artPartCol->begin();
       artPartIter != artPartCol->end();
       ++artPartIter)
   {
      int currentPartType = artPartIter->first;
      DtArticulatedPart* currentPart = artPartIter->second;
         
      DtInfo << "Part Type: " << DtString(currentPartType) << "\n";
         
      // Once we have a chosen a DtArticulatedPart, we can retrieve a vector
      // of the parameter metrics set, and iterate through it.
      std::vector<DtArticulatedPart::ParameterMetric> parameterMetrics;
      currentPart->getParameterMetrics(parameterMetrics);
      
      std::vector<DtArticulatedPart::ParameterMetric>::const_iterator paramMetricIter =
         parameterMetrics.begin();
      std::vector<DtArticulatedPart::ParameterMetric>::const_iterator paramMetricEnd = 
         parameterMetrics.end();

      for(;paramMetricIter != paramMetricEnd; ++paramMetricIter)
       {
          int paramMetric = *paramMetricIter;
          DtArticulatedPart::Parameter parameter;

          currentPart->getParameter(paramMetric, parameter);
           
          DtInfo << "   Param: " << DtString(paramMetric) 
                 << "  Value: " << parameter.value << "\n";          
       }    
   }
}