VR-Forces 4.0.4 Class Documentation: exampleDistributedObject

This example shows how to create an agent for an object and create an instance of the agent in a driver. It creates a distributed object, DtExampleObject, that loads a model and rotates it using an agent.

To fully appreciate this example, use the Distributed Code Generator to generate the agent classes.

The object is defined as follows:

   class DtExampleObject
   {

   public:

      DtExampleObject(DtDe& de, DtUniqueID id);

      virtual ~DtExampleObject();

      void loadModel(const std::string& filename);

      void setRotationAngle(double rotationAngleInDegrees);

To generate the agent files:

Run ./bin/dcgen.exe. The Distributed Code Generator opens.
Choose Files -> Open. An Open dialog box opens.
Select ./examples/exampleDistributedObject/DtExampleObject.ocdx.
Examine the object class definition and compare it to the object code to see how functions for the agent were chosen.
Choose Build -> Set Output Directory.
Specify a directory for the output files. Be careful not to overwrite the files shipped with VR-Vantage.
Choose Build -> Generate Files. (You can also generate files from the command line or from within your IDE. For details, please see VR-Vantage Developer's Guide.)

To add the agent to the driver:

      // Create the agent
      myAgent = DtExampleObjectAgent::create(myAgentManager);

      // Load the model
      myAgent->loadModel("../data/Lifeforms/Animals/cow.osg");

Drivers get ticked every frame. In our driver's tick method, we will tell the agent to rotate to a certain degree:

      myAgent->setRotationAngle(myRotationDegree);

Building the Example

VR-Vantage includes pre-built versions of the example application. To build it yourself, follow the instructions at Building VR-Vantage Examples, Applications, and Plug-ins.

Running the Example

This example is an application. You can run it by running ./bin/exampleDistributedObject.exe (on Windows) or ./bin/exampleDistributedObject (on Linux). For more information about running examples, please see Running Applications and Examples.

Example Source Files

DtExampleObject.h

// /****************************************************************************** 
// ** Copyright (c) 2008 MAK Technologies, Inc. 
// ** All rights reserved. 
// ******************************************************************************/ 
// /****************************************************************************** 
// ** $RCSfile: DtExampleObject.h,v $ $Revision: 1.4 $ $State: Exp $ 
// ******************************************************************************/ 

#ifndef DtExampleObject_H_
#define DtExampleObject_H_

#include <vrvCore/DtDe.h>
#include <vrvCore/DtUniqueID.h>

#include <osg/PositionAttitudeTransform>

#include <string>

namespace makVrv
{
   class DtExampleObject
   {

   public:

      DtExampleObject(DtDe& de, DtUniqueID id);

      virtual ~DtExampleObject();

      void loadModel(const std::string& filename);

      void setRotationAngle(double rotationAngleInDegrees);

   protected:

      DtDe& myDe;
      osg::ref_ptr<osg::PositionAttitudeTransform> myPat;

   };

}

#endif

DtExampleObject.cxx

// /****************************************************************************** 
// ** Copyright (c) 2008 MAK Technologies, Inc. 
// ** All rights reserved. 
// ******************************************************************************/ 
// /****************************************************************************** 
// ** $RCSfile: DtExampleObject.cxx,v $ $Revision: 1.4 $ $State: Exp $ 
// ******************************************************************************/ 
#include "DtExampleObject.h"
#include <vrvOsg/DtOsgRenderer.h>
#include <vrvCore/DtModelSetRealizationManager.h>
#include <vrvCore/DtDeSharedState.h>

#include <vrvOsg/DtOsgRenderer.h>
#include <vrvOsg/DtChannelSpecificGroup.h>

#include <osg/Group>
#include <osg/Node>
#include <osgDB/ReadFile>
#include <osg/ShapeDrawable>
#include <osg/Geode>

namespace makVrv
{

   DtExampleObject::DtExampleObject( DtDe& de, DtUniqueID id )
   : myDe(de)
   , myPat(0)
   {
   }

   DtExampleObject::~DtExampleObject()
   {
   }

   void DtExampleObject::loadModel( const std::string& filename )
   {
      // Add a model...
      osg::ref_ptr<osg::Node> modelNode = osgDB::readNodeFile(filename);   

      // Create a transform for the model.
      myPat = new osg::PositionAttitudeTransform();

      // Add the model to the transform.
      myPat->addChild(modelNode.get());

      // The observer starts at 0,0,0. Move the transform, 100 units away.
      myPat->setPosition(osg::Vec3(0,100,0));

      const DtModelSetRealizationManager& manager = myDe.sharedState().modelSetRealizationManager();
      DtModelSetRealizationManager::ModelSetRealizations::const_iterator iter = manager.modelSetRealizations().begin();
      DtModelSetRealizationManager::ModelSetRealizations::const_iterator end = manager.modelSetRealizations().end();

      while (iter != end)
      {
         if (iter->second)
         {
            // Add the cow to the root of the scene graph.
            ((DtOsgRenderer&)myDe.renderer()).addNodeToRoot(myPat.get(), 
               DtOsgRenderer::visualizerTypeRoot( iter->first, 0 ) );
         }

         ++iter;
      }
   }

   void DtExampleObject::setRotationAngle( double rotationAngleInDegrees )
   {
      myPat->setAttitude(osg::Quat(
         osg::DegreesToRadians(0.0), osg::Vec3d(1.0, 0.0, 0.0),
         osg::DegreesToRadians(0.0), osg::Vec3d(0.0, 1.0, 0.0),
         osg::DegreesToRadians(rotationAngleInDegrees), osg::Vec3d(0.0, 0.0, 1.0)));
   }

}

exampleDistributedObject.cxx

// /****************************************************************************** 
// ** Copyright (c) 2008 MAK Technologies, Inc. 
// ** All rights reserved. 
// ******************************************************************************/ 
// /****************************************************************************** 
// ** $RCSfile: exampleDistributedObject.cxx,v $ $Revision: 1.12 $ $State: Exp $ 
// ******************************************************************************/ 
#include <vrvCore/DtVrvApplication.h>
#include <vrvCore/DtDe.h>
#include <vrvCore/DtAgentManager.h>
#include <vrvCore/DtDriverManager.h>
#include <vrvCore/DtDriver.h>

// The header for the driver generated by the Distributed Object Compiler
#include "DtExampleObjectAgent.hpp"

// Use the VR-Vantage namespace. All classes in VR-Vantage are in this namespace.
using namespace makVrv;

// This driver creates and owns the example driver.
class DtExampleDriver : public DtDriver
{
public:
   DtExampleDriver(DtAgentManager& am)
      : DtDriver(am,"DtExampleDriver")
      , myAgent(0)
      , myRotationDegree(0.0)
   {
   }

   virtual ~DtExampleDriver()
   {
      if(myAgent)
         delete myAgent;
      myAgent = 0;
   }

   virtual const std::string& className() const
   {
      static std::string name = "DtExampleDriver";
      return name;
   }

   virtual bool onStart()
   {      
      // Create the agent
      myAgent = DtExampleObjectAgent::create(myAgentManager);

      // Load the model
      myAgent->loadModel("../data/Lifeforms/Animals/cow.osg");
      return true;
   }

   virtual bool onStop()
   {
      if(myAgent)
         delete myAgent;
      myAgent = 0;
      return true;
   }

   virtual bool onTick()
   {         
      // Rotate the object a little bit every frame.
      myAgent->setRotationAngle(myRotationDegree);
      myRotationDegree += 0.15;
      if(myRotationDegree > 360.0)
      {
         myRotationDegree = 0.0;
      }
      return true;
   }

protected:  

   DtExampleObjectAgent* myAgent;
   double myRotationDegree;

};

int main(int argc,char** argv)
{
   // A DtVrvApplication wraps up all the components required to build a complete
   // VR-Vantage application (DtDe, DtPluginManager, DtEventLoop, and a 
   // DtVrvApplicationConfiguration).
   DtVrvApplication application;

   // This causes the plugin manager to load plugins, cause a Display Configuration
   // to be realized, creates the default environment, etc.
   application.initialize(argc, argv);

   // Create DtExampleDriver.
   DtExampleDriver* driver = new DtExampleDriver(
      application.de().agentManager());

   // The driver is now owned by the display engine. Do not delete it.
   application.de().driverManager().addDriver(driver);      

   // Start the driver, creating a driver.
   application.de().driverManager().startDriver(driver);

   // Creates an event loop and begins running it, causing the creation of frames.
   application.run();
}