source: trunk/VUT/Ogre/src/OgreItemBufferQueryManager.cpp @ 158

#include "OgreItemBufferQueryManager.h"
#include <OgreLogManager.h>
#include <OgreStringConverter.h>
#include <vector>


namespace Ogre {
//----------------------------------------------------------------------- 
ItemBufferQueryManager::ItemBufferQueryManager(PlatformHierarchyInterface *hierarchyInterface, Viewport *vp):
PlatformQueryManager(hierarchyInterface, vp)
{
}
//-----------------------------------------------------------------------
bool ItemBufferQueryManager::ShootRay(const Ray &ray, std::vector<Mesh *> *visibleMeshes, bool isGlobalLine)
{
    // run OGRE ray shooting query
    return false;
}
//-----------------------------------------------------------------------
void ItemBufferQueryManager::ComputeCameraVisibility(const Camera &camera,
                            InfoContainer<GtpVisibility::NodeInfo> *visibleNodes,
                            InfoContainer<GtpVisibility::MeshInfo> *visibleGeometry,
                            bool relativeVisibility)
{
        // initialise item buffer (if not already initialised)
        InitItemBuffer(visibleNodes, visibleGeometry);

        // we need access to the scene manager and the rendersystem
        PlatformHierarchyInterface *pfHierarchyInterface = 
                dynamic_cast<PlatformHierarchyInterface *>(mHierarchyInterface);

        SceneManager *sm = pfHierarchyInterface->GetSceneManager();

        // ---- Render scene with item buffer (i.e., objects with their id as color codes)

        // const_cast allowed because camera is not changed in renderScene
        Camera *pCam = const_cast<Camera *>(&camera); 

        // disable overlays, reset them later
        bool overlayEnabled = mViewport->getOverlaysEnabled();
        mViewport->setOverlaysEnabled(false);

        // set item buffer (must be provided by scene manager)
        bool useItemBuffer = true;
        sm->setOption("UseItemBuffer", &useItemBuffer);
        
        // clear background with black (i.e., not a valid item id)
        ColourValue bg = mViewport->getBackgroundColour();
        mViewport->setBackgroundColour(ColourValue(0, 0, 0, 0));


        // --- render item buffer
        pfHierarchyInterface->GetSceneManager()->_renderScene(pCam, mViewport, false);


        //---- collect results
        int dimx = 0;
        int dimy = 0;

        // get frame buffer
        uchar *buf = mViewport->getTarget()->getBufferContents(dimx, dimy);

        
        // loop through frame buffer & collect visible pixels
        for (int idx = 0; idx < dimy * dimx * 3; idx += 3)
        {
                // -- decode color code to receive id
                int id = buf[idx] << 16;
                id += buf[idx + 1] << 8;
                id += buf[idx + 2];

                // if valid id <= add visibility (id values start at 1
                if ((id > 0) && (id < (int)visibleGeometry->size()))
                {
                        ((*visibleGeometry)[id]).AddVisibility(1, 1);
                }
        }

        //-- reset options

        // don't need item buffer anymore
        useItemBuffer = false;
        sm->setOption("UseItemBuffer", &useItemBuffer);
        // reset initialised - flag
        mWasInitialised = false;
        // reset old overlay status
        mViewport->setOverlaysEnabled(overlayEnabled);
        // reset background color
        mViewport->setBackgroundColour(bg);

        // delete array storing the frame buffer
        delete [] buf;
}
//-----------------------------------------------------------------------
void ItemBufferQueryManager::InitItemBuffer(InfoContainer<GtpVisibility::NodeInfo> *visibleNodes,
                            InfoContainer<GtpVisibility::MeshInfo> *visibleGeometry)
{
        if (mWasInitialised)
                return;

        mWasInitialised = true;

        SceneManager *sm = 
                dynamic_cast<PlatformHierarchyInterface *>(mHierarchyInterface)->GetSceneManager();

        SceneManager::EntityIterator it = sm->getEntityIterator();

        // TODO: make this more efficient
        visibleGeometry->clear();
        visibleNodes->clear();

        while (it.hasMoreElements())
        {
                visibleGeometry->push_back(GtpVisibility::MeshInfo(it.getNext(), 0, 0));
        }
}

} // namespace Ogre