[osg-submissions] Make osgviewerMFC work without salve cameras

[Wang Rui]

Hi Robert,

For a long time, the osgviewerMFC example uses addSlave() to setup the
graphics context and link it with a slave camera. I don't know the
reason we perform like that, which will cause a problem that the
GUIEventHandler may not obtain correct window coordinates because the
main camera will use a default input range to receive events from the
slave camera's graphics context. It is also weird to see the
addSlave() used in non-cluster applications, which beginners will be
confused with.

I've make a slightly modification to the osgviewerMFC example to make
it work without setting slave cameras. I've tested with the MDI
framework and everything seems fine. Do you think it a little better
to be understood and used if we could make such a change to the MFC
example?

Cheers,

Wang Rui

// MFC_OSG.cpp : implementation of the cOSG class
//
#include "stdafx.h"
#include "MFC_OSG.h"


cOSG::cOSG(HWND hWnd) :
   m_hWnd(hWnd) 
{
}

cOSG::~cOSG()
{
    mViewer->setDone(true);
    Sleep(1000);
    mViewer->stopThreading();

    delete mViewer;
}

void cOSG::InitOSG(std::string modelname)
{
    // Store the name of the model to load
    m_ModelName = modelname;

    // Init different parts of OSG
    InitManipulators();
    InitSceneGraph();
    InitCameraConfig();
}

void cOSG::InitManipulators(void)
{
    // Create a trackball manipulator
    trackball = new osgGA::TrackballManipulator();

    // Create a Manipulator Switcher
    keyswitchManipulator = new osgGA::KeySwitchMatrixManipulator;

    // Add our trackball manipulator to the switcher
    keyswitchManipulator->addMatrixManipulator( '1', "Trackball", 
trackball.get());

    // Init the switcher to the first manipulator (in this case the only 
manipulator)
    keyswitchManipulator->selectMatrixManipulator(0);  // Zero based index Value
}


void cOSG::InitSceneGraph(void)
{
    // Init the main Root Node/Group
    mRoot  = new osg::Group;

    // Load the Model from the model name
    mModel = osgDB::readNodeFile(m_ModelName);

    // Optimize the model
    osgUtil::Optimizer optimizer;
    optimizer.optimize(mModel.get());
    optimizer.reset();

    // Add the model to the scene
    mRoot->addChild(mModel.get());
}

void cOSG::InitCameraConfig(void)
{
    // Local Variable to hold window size data
    RECT rect;

    // Create the viewer for this window
    mViewer = new osgViewer::Viewer();

    // Add a Stats Handler to the viewer
    mViewer->addEventHandler(new osgViewer::StatsHandler);
    
    // Get the current window size
    ::GetWindowRect(m_hWnd, &rect);

    // Init the GraphicsContext Traits
    osg::ref_ptr<osg::GraphicsContext::Traits> traits = new 
osg::GraphicsContext::Traits;

    // Init the Windata Variable that holds the handle for the Window to 
display OSG in.
    osg::ref_ptr<osg::Referenced> windata = new 
osgViewer::GraphicsWindowWin32::WindowData(m_hWnd);

    // Setup the traits parameters
    traits->x = 0;
    traits->y = 0;
    traits->width = rect.right - rect.left;
    traits->height = rect.bottom - rect.top;
    traits->windowDecoration = false;
    traits->doubleBuffer = true;
    traits->sharedContext = 0;
    traits->setInheritedWindowPixelFormat = true;
    traits->inheritedWindowData = windata;

    // Create the Graphics Context
    osg::GraphicsContext* gc = 
osg::GraphicsContext::createGraphicsContext(traits.get());

    // Init a new Camera (Master for this View)
    osg::ref_ptr<osg::Camera> camera = new osg::Camera;

    // Assign Graphics Context to the Camera
    camera->setGraphicsContext(gc);

    // Set the viewport for the Camera
    camera->setViewport(new osg::Viewport(traits->x, traits->y, traits->width, 
traits->height));

    // Set projection matrix and camera attribtues
    camera->setClearMask(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
    camera->setClearColor(osg::Vec4f(0.2f, 0.2f, 0.4f, 1.0f));
    camera->setProjectionMatrixAsPerspective(
        30.0f, 
static_cast<double>(traits->width)/static_cast<double>(traits->height), 1.0, 
1000.0);

    // Add the Camera to the Viewer
    //mViewer->addSlave(camera.get());
    mViewer->setCamera(camera.get());

    // Add the Camera Manipulator to the Viewer
    mViewer->setCameraManipulator(keyswitchManipulator.get());

    // Set the Scene Data
    mViewer->setSceneData(mRoot.get());

    // Realize the Viewer
    mViewer->realize();

    // Correct aspect ratio
    /*double fovy,aspectRatio,z1,z2;
    
mViewer->getCamera()->getProjectionMatrixAsPerspective(fovy,aspectRatio,z1,z2);
    aspectRatio=double(traits->width)/double(traits->height);
    
mViewer->getCamera()->setProjectionMatrixAsPerspective(fovy,aspectRatio,z1,z2);*/
}

void cOSG::PreFrameUpdate()
{
    // Due any preframe updates in this routine
}

void cOSG::PostFrameUpdate()
{
    // Due any postframe updates in this routine
}

void cOSG::Render(void* ptr)
{
    cOSG* osg = (cOSG*)ptr;

    osgViewer::Viewer* viewer = osg->getViewer();

    // You have two options for the main viewer loop
    //      viewer->run()   or
    //      while(!viewer->done()) { viewer->frame(); }

    //viewer->run();
    while(!viewer->done())
    {
        osg->PreFrameUpdate();
        viewer->frame();
        osg->PostFrameUpdate();
        //Sleep(10);         // Use this command if you need to allow other 
processes to have cpu time
    }

    // For some reason this has to be here to avoid issue: 
    // if you have multiple OSG windows up 
    // and you exit one then all stop rendering
    AfxMessageBox("Exit Rendering Thread");

    _endthread();
}

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