exampleMultipleChannels

Table of Contents

• Overview
• Expected Result
• Example details
• Building the Example
• Running the Example
• Learn More
• Example Source Files
• exampleMultipleChannelText.cxx
• multipleChannelTextUtilities.h
• multipleChannelTextUtilities.cxx

Overview

Show how to use multiple windows, each with multiple channels rendering a different model-set (with specific text overlay).

Expected Result

Multiple Channel Text Result

Example details

This Vantage application configures the display-engine with one window containing two channels displaying the same scene. Each channel uses a different overlay to display unique 2D text within the channel.

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 ./bin64/exampleMultipleChannelText.exe (on Windows) or ./bin64/exampleMultipleChannelText (on Linux). For more information about running examples, please see Running Applications and Examples.

Learn More

• exampleModelArticulationDistributed
• VR-Vantage Architecture Walkthrough

Example Source Files

• multipleChannelTextUtilities.h
• multipleChannelTextUtilities.cxx
• exampleMultipleChannelText.cxx

---

exampleMultipleChannelText.cxx

/*****************************************************************************
 * Copyright (c) 2019 MAK Technologies, Inc.
 * All rights reserved.
 *****************************************************************************/



#include <string>
#include <sstream>
#include <iostream>

#include <vrvCore/DtDe.h>
#include <vrvCore/DtVrvApplication.h>
#include <vrvCore/DtStealthConfiguration.h>

#include <vrvUtil/DtDisplayConfiguration.h>

#include "multipleChannelTextUtilities.h"

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


// The main function configures the display-engine with one window
// containing two channels displaying the same scene.  Each channel
// uses a different overlay to display unique 2D text within the channel.
int main(int argc, char** argv)
{
   // A DtVrvApplication wraps up all the components required to build a
   // complete VR-Vantage application.  This application configures the
   // DtVrvApplication to be an Stealth application.  Doing so will
   // automatically read the default observer modes we wish to use.
   DtStealthConfiguration config;   
   DtVrvApplication app(config);

   // Initializing the application sets up the default environment, loads
   // the plug-ins and sets up the default configuration.
   app.initialize(argc, argv);

   // Always create the display configuration after initializing the
   // application.  Custom configurations added before the application is
   // initialized will be overwritten with default configuration during
   // initialization.  The makeDisplayConfiguration() function is a custom
   // function for this example.  It returns full configuration for the app.
   DtDisplayConfiguration dc = makeDisplayConfiguration(app.de());

   // Try to add this configuration to the Display Engine.
   if(app.de().addDisplayConfiguration(dc))
   {
      // Realize the display configuration on this display engine 
      // causing the windows and channels to be created.       
      std::string displayName = app.de().igCommunicator().name();
      app.de().realizeDisplayConfiguration(displayName, dc.name());

      // Create 2D Overlays per window/channel.  The overlays only need
      // to be created once and can be used in multiple channels.  This
      // app creates two overlays, one for each channel.
      create2dOverlays(app.de());

      // Populate 2D Overlays with separate text per channel.  The text
      // in each channel-overlay can be manipulated during runtime.  This
      // app just populates the text just before rendering.
      populate2dOverlays(app.de());

      // Load all the models into the scene.
      loadTheScene(app.de());
   }
   else
   {
      std::cerr << "Could not add display configuration: "
         << dc.name() << std::endl;
   }

   // Create an event loop and begin running the display engine.
   app.run();

   return 0;
}

multipleChannelTextUtilities.h

/*****************************************************************************
 * Copyright (c) 2019 MAK Technologies, Inc.
 * All rights reserved.
 *****************************************************************************/


#pragma once

#include <vrvGraphics/DtFontManager.h>
#include <vrvGraphics/DtOverlayRenderer.h>

#include <vrvCore/DtChannelManager.h>
#include <vrvCore/DtOverlayManager.h>

#include <vrvUtil/DtChannelConfiguration.h>
#include <vrvUtil/DtDisplayConfiguration.h>
#include <vrvUtil/DtWindowConfiguration.h>

#include <matrix/vlVector.h>

#include <string>

namespace makVrv 
{ 
   class DtDe; 
   class DtChannel; 
}

// This example provides examples of multiple ways to create and use 2D overlays
// in VR-Vantage.  It creates a window with two channels.  It then creates a custom 
// channel-specific overlay for the second channel, and a second overlay that is
// drawn on all channels. It then shows how to put text objects onto the custom
// overlays, as well as text onto the default channel-specific for first channel.
// 

extern void createCustomOverlay( makVrv::DtDe& de, makVrv::DtChannel* channel,
   makVrv::DtOverlayManager::DefaultOverlays layerId );


extern void createCustomMultiChannelOverlay( makVrv::DtDe& de, 
   makVrv::DtChannelManager::ChannelMap& channels,
   makVrv::DtOverlayManager::DefaultOverlays layerId );

extern void putTextOnOverlay(makVrv::DtDe& de, makVrv::DtOverlayRenderer& renderer,
   const std::string& text, const DtVector& position, makVrv::DtFontSP font );

extern void create2dOverlays(makVrv::DtDe& de);

extern void populate2dOverlays(makVrv::DtDe& de);



extern makVrv::DtChannelConfiguration makeChannelConfiguration(
   makVrv::DtDe& de, double left=0, double right=100, double bottom=0,
   double top=100);

extern makVrv::DtWindowConfiguration makeWindowConfiguration(
   makVrv::DtDe& de, int x=100, int y=100);


extern makVrv::DtDisplayConfiguration makeDisplayConfiguration(
   makVrv::DtDe& de, const std::string& name = "My Display Configuration");

extern std::string registerModelDefinition(
   makVrv::DtDe& de, const std::string& dataFile);


extern void addModelToTheScene(makVrv::DtDe& de, const std::string& modelName);


void loadTheScene(makVrv::DtDe& de);

multipleChannelTextUtilities.cxx

/*****************************************************************************
 * Copyright (c) 2021 MAK Technologies, Inc.
 * All rights reserved.
 *****************************************************************************/



#include "multipleChannelTextUtilities.h"

#include <matrix/vlTaitBryan.h>

#include <vrvCore/DtChannel.h>
#include <vrvCore/DtDe.h>
#include <vrvCore/DtDeSharedState.h>
#include <vrvCore/DtDisplay.h>
#include <vrvCore/DtDriverManager.h>
#include <vrvCore/DtInputDriver.h>
#include <vrvCore/DtModelDefinition.h>
#include <vrvCore/DtModelInstance.h>
#include <vrvCore/DtObserverObject.h>
#include <vrvCore/DtObserverMode.h>
#include <vrvCore/DtSceneObject.h>
#include <vrvCore/DtWindow.h>
#include <vrvCore/DtWindowManager.h>

#include <vrvGraphics/DtTextRenderer.h>

#include <vrvOsg/DtCameraNode.h>
#include <vrvOsg/DtOsgChannel.h>
#include <vrvOsg/DtOsgOverlayManager.h>
#include <vrvOsg/DtOsgRenderer.h>
#include <vrvOsg/DtOsgSimpleModel.h>
#include <vrvOsg/DtOverlayDrawable.h>

#include <vrvUtil/DtObserverConfiguration.h>
#include <vrvUtil/DtContainerInitializers.h>

#include <iostream>


#define CUSTOM_TEXT_USES_NORMALIZED_COORDS 1

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


// This is the filename of a model that will be added to the scene
const std::string vehicle("$(DATA_DIR)/Vehicles/Wheeled/Fiat_124/Fiat_124.medf");

// Pointer to the first channel.  This is how we access the default channel-
// specific overlay on channel 1
DtChannel* channel1Ptr = 0;

// Define this externally, since we need it to create the custom overlay and to
// populated it.  This is how we access the custom overlay created on channel 2
DtOverlayManager::DefaultOverlays customOverlay = DtOverlayManager::UserStart;
DtOverlayManager::DefaultOverlays customMultiChannelOverlay = 
   (DtOverlayManager::DefaultOverlays) ( DtOverlayManager::UserStart + 1 );

// Use a fixed window size.
const unsigned int windowW(800);
const unsigned int windowH(600);

// Specify the window coordinates for each channel
DtVector channel1Coords(  1.0, 49.0, 0.0);
DtVector channel2Coords( 51.0, 99.0, 0.0);

#if CUSTOM_TEXT_USES_NORMALIZED_COORDS
DtVector customOverlayTextCoords( 0.1, 0.033, 0.0 );
DtVector customMC_OverlayTextCoords( 0.35, 0.5, 0. );
#else
DtVector customOverlayTextCoords( 0.01 * windowW + 20.0, 20., 0. );
DtVector customMC_OverlayTextCoords( 0.35 * windowW, 300., 0. );
#endif

DtVector channelSpecificOverlayTextCoords( channel1Coords.x() * 0.01 * windowW + 20.0, 20., 0. );

void createCustomOverlay(DtDe& de, DtChannel* channel, 
   DtOverlayManager::DefaultOverlays layerId )
{
   // Get the overlay manager.
   DtOsgOverlayManager& manager =
      dynamic_cast<DtOsgOverlayManager&>(de.renderer().overlayManager());

   // This will create the new overlay renderer (the same call
   // will get an existing one)
   DtOverlayRenderer& ovlRenderer = manager.overlayRenderer( layerId );

   // Create the drawable that we will put under the camera that will
   // render this overlay
   osg::ref_ptr<DtOverlayDrawable> overlayDrawable =
      new DtOverlayDrawable(manager, *channel, de.sharedState().useReverseZBuffer());

   // Add the overlay to the drawable
   overlayDrawable->setOverlayToRender(& ovlRenderer );

   // Look up the 2D camera (a child of the channel camera).
   // When using this camera, objects on the overlay are specified
   // in pixels.  The alternatives are:
   // osgChannel->normalizedOverlayCamera()
   //    Overlay objects used normalized window coordinates (0. - 1.)
   // osgChannel->sceneCamera()
   //   Overlay objects specified in local (database) coordinates
   //   You must also call ovlRenderer.setProjectCameraIs3D(true)
   DtOsgChannel* osgChannel = dynamic_cast<DtOsgChannel*>(channel); 

   if (osgChannel)
   {
#if CUSTOM_TEXT_USES_NORMALIZED_COORDS
      DtCameraNode* d2Camera = osgChannel->normalizedOverlayCamera();
#else
      DtCameraNode* d2Camera = osgChannel->overlayCamera();
#endif
      if (d2Camera)
      {
         osg::Geode* geode = new osg::Geode;
         geode->addDrawable(overlayDrawable);
         d2Camera->addChild(geode);
         overlayDrawable->setProjectionCamera(d2Camera);
         ovlRenderer.setProjectCameraIs3D(false);
#if CUSTOM_TEXT_USES_NORMALIZED_COORDS
         ovlRenderer.setProjectCameraIsNormalized(true);
#else
         ovlRenderer.setProjectCameraIsNormalized(false);
#endif
      }
   }
}

void createCustomMultiChannelOverlay( makVrv::DtDe& de, 
   makVrv::DtChannelManager::ChannelMap& channels,
   makVrv::DtOverlayManager::DefaultOverlays layerId )
{
   // Get the overlay manager.
   DtOsgOverlayManager& manager =
      dynamic_cast<DtOsgOverlayManager&>(de.renderer().overlayManager());

   // This will create the new overlay renderer (the same call
   // will get an existing one)
   DtOverlayRenderer& ovlRenderer = manager.overlayRenderer( layerId );

   DtChannelManager::ChannelMap::iterator curIter = channels.begin();
   DtChannelManager::ChannelMap::iterator endIter = channels.end();
   for( ; curIter != endIter; ++curIter )
   {
      DtOsgChannel* osgChannel = dynamic_cast<DtOsgChannel*>(curIter->second); 

      if (osgChannel)
      {
         // Create the drawable that we will put under the camera that will
         // render this overlay
         osg::ref_ptr<DtOverlayDrawable> overlayDrawable =
            new DtOverlayDrawable(manager, *osgChannel, de.sharedState().useReverseZBuffer());

         // Add the overlay to the drawable
         overlayDrawable->setOverlayToRender(& ovlRenderer );

#if CUSTOM_TEXT_USES_NORMALIZED_COORDS
         DtCameraNode* d2Camera = osgChannel->normalizedOverlayCamera();
#else
         DtCameraNode* d2Camera = osgChannel->overlayCamera();
#endif
         if (d2Camera)
         {
            osg::Geode* geode = new osg::Geode;
            geode->addDrawable(overlayDrawable);
            d2Camera->addChild(geode);
            overlayDrawable->setProjectionCamera(d2Camera);
            ovlRenderer.setProjectCameraIs3D(false);
#if CUSTOM_TEXT_USES_NORMALIZED_COORDS
            ovlRenderer.setProjectCameraIs3D(true);
#else
            ovlRenderer.setProjectCameraIs3D(false);
#endif
         }
      }
   }
}

void create2dOverlays(DtDe& de)
{
   // Get the window list for the display.
   const DtWindowManager::WindowList& windows =
      de.display()->windowManager().windows();

   // Get the window 
   DtWindow* win = *(windows.begin());

   // Get the channel map for the window. It maps channel names to
   // DtChannel*'s.
   DtChannelManager::ChannelMap& cm(win->channelManager().channels());

   // Use one of the existing channel-specific overlays for the first channel.  
   // Each channel has 2 channel specific overlays - one that uses the scene
   // camera (so objects are specified in local coordinates) and one
   // that uses the overlay camera (objects specified in pixel coordinates

   // We don't need to do anything here except store the channel pointer;
   // the channel-specific overlays already exist.
   channel1Ptr = (cm.find("Channel 1"))->second;


   // Now set up and create the custom overlay for the second channel

   // Get Channel 2
   DtChannel* channel = (cm.find("Channel 2"))->second;

   // Create a custom channel-specific overlay
   createCustomOverlay( de, channel, customOverlay );

   // Lastly, set up a multi-channel overlay
   createCustomMultiChannelOverlay( de, cm, customMultiChannelOverlay );
}

void putTextOnOverlay(makVrv::DtDe& de, makVrv::DtOverlayRenderer& renderer,
   const std::string& text, const DtVector& position, DtFontSP font )
{
   // Create the text object on the overlay.
   DtTextProxy* textProxy = renderer.textRenderer().createProxy();

   // Initialize the text.
   if (textProxy)
   {
      textProxy->setPosition(position.x(), position.y(), position.z());
      textProxy->setString(DtUnicode::fromAscii(text.c_str()));
      textProxy->setColor(1.0, 0.5, 0.0, 1.0);
      textProxy->setFont(font);

      // Left-to-right text, set bounds to get '\n' to work
      // (right-to-left text does not need bounds to get '\n' to work)
      DtBoundingBox bbox;
      bbox.expandTo(windowW, windowH);
      bbox.centerOn(Dt2dPoint(windowW / 2., windowH / 2.));
      textProxy->setBounds(bbox);
   }
}

void populate2dOverlays(makVrv::DtDe& de)
{
   // Get a font for the text.
   DtOsgRenderer& osgRenderer(dynamic_cast<DtOsgRenderer&>(de.renderer()));
   DtFontManager& fontMgr(osgRenderer.fontManager());
   DtFontSP font = fontMgr.getFont("../data/Fonts/arial.ttf", 16);

   // Get the overlay manager
   DtOsgOverlayManager& manager =
      dynamic_cast<DtOsgOverlayManager&>(de.renderer().overlayManager());

   // Access the default channel-specific overlay (that uses the overlay camera)
   // using the channel pointer.  To get the other channel-specific overlay for
   // this channel (the one that uses the scene camera) call
   // manager.overlayRenderer3D( channel2Ptr ) instead.
   DtOverlayRenderer& channelSpecificOvlRenderer = manager.overlayRenderer( 
      channel1Ptr );
   putTextOnOverlay(de, channelSpecificOvlRenderer, "Channel-specific Overlay", 
      channelSpecificOverlayTextCoords, font);

   // Access the custom overlay, using the custom overlay layer id
   DtOverlayRenderer& customOvlRenderer = manager.overlayRenderer( 
      customOverlay );
   putTextOnOverlay(de, customOvlRenderer, "Custom Overlay", 
      customOverlayTextCoords, font);

   // Access the custom multi-channel overlay, using the custom overlay layer id
   DtOverlayRenderer& customMultiChannelOvlRenderer = manager.overlayRenderer( 
      customMultiChannelOverlay );

   putTextOnOverlay(de, customMultiChannelOvlRenderer, "Custom Multi Channel", 
      customMC_OverlayTextCoords, font);   
}

DtChannelConfiguration makeChannelConfiguration(
   DtDe& de, double left, double right, double bottom, double top)
{
   // Id value to make the channel and observer names unique
   static DtUniqueID id(1);
   std::stringstream idName;
   idName << " " << id++;

   // Create a new observer for this channel.
   std::string oName = DtObserverConfiguration::ObserverConfigurationString;
   oName += idName.str();
   DtObserverConfiguration observerConfig(oName);

   // Set the observer mode to stealth.
   observerConfig.setObserverMode(std::string("3D"));

   // Register the observer-configuration for the channel to use later.
   de.driverManager().inputDriver().addObserverConfiguration(observerConfig);

   // Create a channel, giving it a unique name.
   std::string cName = DtChannelConfiguration::DefaultChannelString;
   cName += idName.str();
   DtChannelConfiguration channelConfig(cName);

   // Set the viewport for this channel (where it will render within a window).
   // The default is to fill the entire window.
   channelConfig.setViewport(left, right, bottom, top);

   // Set the observer that the channel will use.
   channelConfig.setObserverName(oName);

   // return the configuration for this channel.
   return channelConfig;
}


DtWindowConfiguration makeWindowConfiguration(DtDe& de, int x, int y)
{
   // Id value to make the window name unique
   static DtUniqueID id(1);
   std::stringstream idName;
   idName << " " << id++;

   // Create a window, giving it a unique name.
   std::string wName = DtWindowConfiguration::DefaultWindowString;
   wName += idName.str();
   DtWindowConfiguration windowConfig(wName);

   // Set the type and position for this window.
   windowConfig.setWindowType(DtWindowConfiguration::Window);
   windowConfig.setPosition(x, y);
   windowConfig.setSize(windowW, windowH);

   // Create the channel-configurations for this window.
   // Note: channels are configured slightly less then window sizes
   //       to display a visible (black) boarder around each channel.

   windowConfig.channelConfigurations().add(
      makeChannelConfiguration(de, channel1Coords.x(), channel1Coords.y(), 1, 99));

   windowConfig.channelConfigurations().add(
      makeChannelConfiguration(de, channel2Coords.x(), channel2Coords.y(), 1, 99));


   // return the configuration for this window.
   return windowConfig;
}


DtDisplayConfiguration makeDisplayConfiguration(DtDe& de, const std::string& name)
{
   // Configure a display with one window containing two channels.
   DtDisplayConfiguration dc;
   dc.setName(name);
   dc.windowConfigurations().add(makeWindowConfiguration(de));

   return dc;
}

std::string registerModelDefinition(DtDe& de, const std::string& dataFile)
{
   // Id value to make the model name unique
   static DtUniqueID id(1);
   std::stringstream modelName;
   modelName << "model " << id;

   // Create a model definition describing the model to load.
   // The DtModelDefinition class is used to describe several attributes about
   // the model.  This example just specifies the name of the geometry file to
   // load.
   DtModelDefinition md(modelName.str());
   md.setParameter("filename", dataFile);

   // Retrieve the DtDeSharedState from the display engine and register the
   // definition.  The DtDeSharedState contains a model definition manager.  
   // When registering with the DtDeSharedState, all distributed applications
   // are notified to register the same model definition.
   de.sharedState().addModelDefinition(md);

   // return the unique name for the model definition.
   ++id;
   return modelName.str();
}


void addModelToTheScene(DtDe& de, const std::string& modelName)
{
   // Id value to make the scene-object name unique
   static DtUniqueID id(1);

   // Create a DtSceneObject to hold the model.  DtSceneObjects provide an
   // an API to 'group' multiple models together into a single association.
   // The scene-object can then be used to manipulate all the associated
   // models as a single entity.  Among other features like positioning and
   // orientating the associated models, the DtSceneObject also provides the
   // ability to add models to the scene-graph and channels for rendering.
   // This example creates a single DtSceneObject for each channel and 
   // positions its models away from the eye-point in the scene.
   DtSceneObject* sceneObj = new DtSceneObject(de, id);
   sceneObj->setPosition(0, DtVector(0.0f, 5.0f, 0.0f));
   sceneObj->setOrientation(0, DtTaitBryan(
      osg::DegreesToRadians(-150.0f),
      osg::DegreesToRadians(-30.0f),
      osg::DegreesToRadians(-10.0f)));

   // Tell each DtSceneObject to use the model-set for a stealth window.
   sceneObj->setModelSet(DtObserverMode::ModelSet3dModels);

   // Create a model and set its definition to a preregistered definition.
   // A DtModel (in this case a DtOsgSimpleModel) is a managing container for
   // a single model-instance.  It provides rendering attributes about the
   // model-instance, such as the visualizer-type for choosing which channel
   // the model will render in.  Each model requires a unique id. Since this
   // is just an example, arbitrarily pick the same id as the scene-object.
   DtOsgSimpleModel* model = new DtOsgSimpleModel(de, id);
   model->setModelDefinition(modelName);

   // Associate the model with the scene-object.  When a model is associated
   // with a scene-object, the scene-object automatically inserts the model-
   // instance (within the model) into the scene-graph of the renderer in the
   // appropriate channel.
   sceneObj->addModel(model, 0);
   ++id;
}


void loadTheScene(DtDe& de)
{
   std::string modelName = registerModelDefinition(de, vehicle);
   std::cerr << "Adding Model: [" << modelName << "] " << vehicle << std::endl;
   addModelToTheScene(de, modelName);

}

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