C++ MapFrame类代码示例

void
StreamingTile::installRequests( const MapFrame& mapf, int stamp )
{
    StreamingTerrainNode* terrain     = getStreamingTerrain();
    OSGTileFactory*   tileFactory = terrain->getTileFactory();

    bool hasElevationLayer;
    {
        Threading::ScopedReadLock sharedLock( _tileLayersMutex );
        hasElevationLayer = this->getElevationLayer() != NULL;
    }

    if ( hasElevationLayer )
    {
        resetElevationRequests( mapf );     
    }

    // safely loop through the map layers and schedule imagery updates for each:
    for( ImageLayerVector::const_iterator i = mapf.imageLayers().begin(); i != mapf.imageLayers().end(); ++i )
    {
        updateImagery( i->get(), mapf, tileFactory );
    }

    _requestsInstalled = true;
}

bool
CacheSeed::cacheTile(const MapFrame& mapf, const TileKey& key ) const
{
    bool gotData = false;

    for( ImageLayerVector::const_iterator i = mapf.imageLayers().begin(); i != mapf.imageLayers().end(); i++ )
    {
        ImageLayer* layer = i->get();
        if ( layer->isKeyValid( key ) )
        {
            GeoImage image = layer->createImage( key );
            if ( image.valid() )
                gotData = true;
        }
    }

    if ( mapf.elevationLayers().size() > 0 )
    {
        osg::ref_ptr<osg::HeightField> hf;
        mapf.getHeightField( key, false, hf );
        if ( hf.valid() )
            gotData = true;
    }

    return gotData;
}

void
TileModelFactory::buildElevation(const TileKey&    key,
                                 const MapFrame&   frame,
                                 bool              accumulate,
                                 TileModel*        model,
                                 ProgressCallback* progress)
{     
    const MapInfo& mapInfo = frame.getMapInfo();

    const osgEarth::ElevationInterpolation& interp =
        frame.getMapOptions().elevationInterpolation().get();

    // Request a heightfield from the map, falling back on lower resolution tiles
    // if necessary (fallback=true)
    osg::ref_ptr<osg::HeightField> hf;

    bool isFallback = false;

    if (_hfCache->getOrCreateHeightField(frame, key, accumulate, hf, isFallback, SAMPLE_FIRST_VALID, interp, progress))
    {
        model->_elevationData = TileModel::ElevationData(
            hf,
            GeoLocator::createForKey( key, mapInfo ),
            isFallback );

        // Edge normalization: requires adjacency information
        if ( _terrainOptions.normalizeEdges() == true )
        {
            for( int x=-1; x<=1; x++ )
            {
                for( int y=-1; y<=1; y++ )
                {
                    if ( x != 0 || y != 0 )
                    {
                        TileKey nk = key.createNeighborKey(x, y);
                        if ( nk.valid() )
                        {
                            osg::ref_ptr<osg::HeightField> hf;
                            if (_hfCache->getOrCreateHeightField(frame, nk, accumulate, hf, isFallback, SAMPLE_FIRST_VALID, interp, progress) )
                            {
                                model->_elevationData.setNeighbor( x, y, hf.get() );
                            }
                        }
                    }
                }
            }

            // parent too.
            if ( key.getLOD() > 0 )
            {
                osg::ref_ptr<osg::HeightField> hf;
                if ( _hfCache->getOrCreateHeightField(frame, key.createParentKey(), accumulate, hf, isFallback, SAMPLE_FIRST_VALID, interp, progress) )
                {
                    model->_elevationData.setParent( hf.get() );
                }
            }
        }
    }
}

FilterContext
ClampFilter::push( FeatureList& features, const FilterContext& cx )
{
    const Session* session = cx.getSession();
    if ( !session ) {
        OE_WARN << LC << "No session - session is required for elevation clamping" << std::endl;
        return cx;
    }

    // the map against which we'll be doing elevation clamping
    MapFrame mapf = session->createMapFrame( Map::ELEVATION_LAYERS );

    const SpatialReference* mapSRS     = mapf.getProfile()->getSRS();
    const SpatialReference* featureSRS = cx.profile()->getSRS();
    bool isGeocentric = session->getMapInfo().isGeocentric();

    // establish an elevation query interface based on the features' SRS.
    ElevationQuery eq( mapf );

    for( FeatureList::iterator i = features.begin(); i != features.end(); ++i )
    {
        Feature* feature = i->get();
        
        GeometryIterator gi( feature->getGeometry() );
        while( gi.hasMore() )
        {
            Geometry* geom = gi.next();

            if ( isGeocentric )
            {
                // convert to map coords:
                cx.toWorld( geom );
                mapSRS->transformFromECEF( geom );

                // populate the elevations:
                eq.getElevations( geom, mapSRS );

                // convert back to geocentric:
                mapSRS->transformToECEF( geom );
                cx.toLocal( geom );
            }

            else
            {
                // clamps the entire array to the highest available resolution.
                eq.getElevations( geom, featureSRS );
            }
        }
    }

    return cx;
}

void MapLayer::setMap(MapFrame *map)
{
    Q_D(MapLayer);
    if (map == d->map)
        return;
    MapFrame *m = d->map;
    d->map = map;
    if (m)
        m->unregisterLayer(this);
    if (d->map)
        d->map->registerLayer(this);

    emit mapChanged(d->map);
}

bool
ElevationPool::getTile(const TileKey& key, MapFrame& frame, osg::ref_ptr<ElevationPool::Tile>& output)
{
    // Synchronize the MapFrame to its Map; if there's an update,
    // clear out the internal cache and MRU.
    if ( frame.needsSync() )
    {
        if (frame.sync())
        {
            // Probably unnecessary because the Map itself will clear the pool.
            clear();
        }
    }
   
    OE_START_TIMER(get);

    const double timeout = 30.0;
    osg::ref_ptr<Tile> tile;
    while( tryTile(key, frame, tile) && !tile.valid() && OE_GET_TIMER(get) < timeout)
    {
        // condition: another thread is working on fetching the tile from the map,
        // so wait and try again later. Do this until we succeed or time out.
        OpenThreads::Thread::YieldCurrentThread();
    }

    if ( !tile.valid() && OE_GET_TIMER(get) >= timeout )
    {
        // this means we timed out trying to fetch the map tile.
        OE_TEST << LC << "Timeout fetching tile " << key.str() << std::endl;
    }

    if ( tile.valid() )
    {
        if ( tile->_hf.valid() )
        {
            // got a valid tile, so push it to the query set.
            output = tile.get();
        }
        else
        {
            OE_WARN << LC << "Got a tile with an invalid HF (" << key.str() << ")\n";
        }
    }

    return tile.valid();
}

void
StreamingTerrainNode::updateTaskServiceThreads( const MapFrame& mapf )
{
    //Get the maximum elevation weight
    float elevationWeight = 0.0f;
    for (ElevationLayerVector::const_iterator itr = mapf.elevationLayers().begin(); itr != mapf.elevationLayers().end(); ++itr)
    {
        ElevationLayer* layer = itr->get();
        float w = layer->getElevationLayerOptions().loadingWeight().value();
        if (w > elevationWeight) elevationWeight = w;
    }

    float totalImageWeight = 0.0f;
    for (ImageLayerVector::const_iterator itr = mapf.imageLayers().begin(); itr != mapf.imageLayers().end(); ++itr)
    {
        totalImageWeight += itr->get()->getImageLayerOptions().loadingWeight().value();
    }

    float totalWeight = elevationWeight + totalImageWeight;

    if (elevationWeight > 0.0f)
    {
        //Determine how many threads each layer gets
        int numElevationThreads = (int)osg::round((float)_numLoadingThreads * (elevationWeight / totalWeight ));
        OE_INFO << LC << "Elevation Threads = " << numElevationThreads << std::endl;
        getElevationTaskService()->setNumThreads( numElevationThreads );
    }

    for (ImageLayerVector::const_iterator itr = mapf.imageLayers().begin(); itr != mapf.imageLayers().end(); ++itr)
    {
        const TerrainLayerOptions& opt = itr->get()->getImageLayerOptions();
        int imageThreads = (int)osg::round((float)_numLoadingThreads * (opt.loadingWeight().value() / totalWeight ));
        OE_INFO << LC << "Image Threads for " << itr->get()->getName() << " = " << imageThreads << std::endl;
        getImageryTaskService( itr->get()->getUID() )->setNumThreads( imageThreads );
    }
}

bool
ElevationPool::fetchTileFromMap(const TileKey& key, MapFrame& frame, Tile* tile)
{
    tile->_loadTime = osg::Timer::instance()->tick();

    osg::ref_ptr<osg::HeightField> hf = new osg::HeightField();
    hf->allocate( _tileSize, _tileSize );

    // Initialize the heightfield to nodata
    hf->getFloatArray()->assign( hf->getFloatArray()->size(), NO_DATA_VALUE );

    TileKey keyToUse = key;
    while( !tile->_hf.valid() && keyToUse.valid() )
    {
        bool ok;
        if (_layers.empty())
        {
            OE_TEST << LC << "Populating from FULL MAP (" << keyToUse.str() << ")\n";
            ok = frame.populateHeightField(hf, keyToUse, false /*heightsAsHAE*/, 0L);
        }
        else
        {
            OE_TEST << LC << "Populating from layers (" << keyToUse.str() << ")\n";
            ok = _layers.populateHeightFieldAndNormalMap(hf.get(), 0L, keyToUse, 0L, INTERP_BILINEAR, 0L);
        }

        if (ok)
        {
            tile->_hf = GeoHeightField( hf.get(), keyToUse.getExtent() );
            tile->_bounds = keyToUse.getExtent().bounds();
        }
        else
        {
            keyToUse = keyToUse.createParentKey();
        }
    }

    return tile->_hf.valid();
}

void
TileModelFactory::createTileModel(const TileKey&           key, 
                                  const MapFrame&          frame,
                                  bool                     accumulate,
                                  osg::ref_ptr<TileModel>& out_model,
                                  ProgressCallback*        progress)
{

    osg::ref_ptr<TileModel> model = new TileModel( frame.getRevision(), frame.getMapInfo() );

    model->_useParentData = _terrainReqs->parentTexturesRequired();

    model->_tileKey = key;
    model->_tileLocator = GeoLocator::createForKey(key, frame.getMapInfo());

    OE_START_TIMER(fetch_imagery);

    // Fetch the image data and make color layers.
    unsigned index = 0;
    unsigned order = 0;
    for( ImageLayerVector::const_iterator i = frame.imageLayers().begin(); i != frame.imageLayers().end(); ++i )
    {
        ImageLayer* layer = i->get();

        if ( layer->getEnabled() && layer->isKeyInRange(key) )
        {
            BuildColorData build;
            build.init( key, layer, order, frame.getMapInfo(), _terrainOptions, _liveTiles.get(), model.get() );

            bool addedToModel = build.execute(progress);
            if ( addedToModel )
            {
                // only bump the order if we added something to the data model.
                order++;
            }
        }
    }

    if (progress)
        progress->stats()["fetch_imagery_time"] += OE_STOP_TIMER(fetch_imagery);

    
    // make an elevation layer.
    OE_START_TIMER(fetch_elevation);
    buildElevation(key, frame, accumulate, _terrainReqs->elevationTexturesRequired(), model.get(), progress);
    if (progress)
        progress->stats()["fetch_elevation_time"] += OE_STOP_TIMER(fetch_elevation);
    
    // make a normal map layer (if necessary)
    if ( _terrainReqs->normalTexturesRequired() )
    {
        OE_START_TIMER(fetch_normalmap);
        buildNormalMap(key, frame, accumulate, model.get(), progress);
        if (progress)
            progress->stats()["fetch_normalmap_time"] += OE_STOP_TIMER(fetch_normalmap);
    }

    // If nothing was added, not even a fallback heightfield, something went
    // horribly wrong. Leave without a tile model. Chances are that a parent tile
    // not not found in the live-tile registry.
    if ( model->_colorData.size() == 0 && !model->_elevationData.getHeightField() )
    {
        return;
    }

    // OK we are making a tile, so if there's no heightfield yet, make an empty one (and mark it
    // as fallback data of course)
    if ( !model->_elevationData.getHeightField() )
    {
        osg::HeightField* hf = HeightFieldUtils::createReferenceHeightField( key.getExtent(), 15, 15 );
        model->_elevationData = TileModel::ElevationData(
            hf,
            GeoLocator::createForKey(key, frame.getMapInfo()),
            true );
    }

    // look up the parent model and cache it.
    osg::ref_ptr<TileNode> parentTile;
    if ( _liveTiles->get(key.createParentKey(), parentTile) )
    {
        model->_parentModel = parentTile->getTileModel();
    }

    out_model = model.release();
}

void
TileModelFactory::buildNormalMap(const TileKey&    key,
                                 const MapFrame&   frame,
                                 bool              accumulate,
                                 TileModel*        model,
                                 ProgressCallback* progress)
{   
    const MapInfo& mapInfo = frame.getMapInfo();

    const osgEarth::ElevationInterpolation& interp =
        frame.getMapOptions().elevationInterpolation().get();

    // Request a heightfield from the map, falling back on lower resolution tiles
    // if necessary (fallback=true)
    osg::ref_ptr<osg::HeightField> hf;
    osg::ref_ptr<osg::HeightField> parentHF;
    osg::ref_ptr<const TileModel>  parentModel;

    bool isFallback = false;

    unsigned minNormalLOD =
        _terrainOptions.minNormalMapLOD().isSet() ?
        _terrainOptions.minNormalMapLOD().get() : 0u;

    if ( key.getLOD() >= minNormalLOD )
    {
        // look up the parent's heightfield to use as a template
    
        TileKey parentKey = key.createParentKey();
        if ( accumulate )
        {
            osg::ref_ptr<TileNode> parentNode;
            if (_liveTiles->get(parentKey, parentNode))
            {
                parentModel = parentNode->getTileModel();
                parentHF = parentModel->_normalData.getHeightField();
                if ( parentHF->getNumColumns() == EMPTY_NORMAL_MAP_SIZE )
                    parentHF = 0L;
            }
        }

        // Make a new heightfield:
        if (_normalHFCache->getOrCreateHeightField(frame, key, parentHF.get(), hf, isFallback, SAMPLE_FIRST_VALID, interp, progress))
        {
            if ( isFallback && parentModel.valid() )
            {
                model->_normalData = parentModel->_normalData;
                model->_normalData._fallbackData = true;
            }
            else
            {
                model->_normalData = TileModel::NormalData(
                    hf,
                    GeoLocator::createForKey( key, mapInfo ),
                    isFallback );
            }
        }
    }

    else
    {
        // empty HF must be at least 2x2 for normal texture gen to work
        hf = HeightFieldUtils::createReferenceHeightField(
            key.getExtent(), EMPTY_NORMAL_MAP_SIZE, EMPTY_NORMAL_MAP_SIZE, true );

        model->_normalData = TileModel::NormalData(
            hf,
            GeoLocator::createForKey( key, mapInfo ),
            false );
    }

    if ( isFallback && parentModel.valid() )
    {
        model->_normalTexture = parentModel->_normalTexture.get();
    }
    else
    {
        model->generateNormalTexture();
    }
}

bool
HeightFieldCache::getOrCreateHeightField(const MapFrame&                 frame,
                                         const TileKey&                  key,
                                         //bool                            cummulative,
                                         const osg::HeightField*         parent_hf,
                                         osg::ref_ptr<osg::HeightField>& out_hf,
                                         bool&                           out_isFallback,
                                         ElevationSamplePolicy           samplePolicy,
                                         ElevationInterpolation          interp,
                                         ProgressCallback*               progress )
{                
    // default
    out_isFallback = false;

    // check the quick cache.
    HFKey cachekey;
    cachekey._key          = key;
    cachekey._revision     = frame.getRevision();
    cachekey._samplePolicy = samplePolicy;

    if (progress)
        progress->stats()["hfcache_try_count"] += 1;

    bool hit = false;
    LRUCache<HFKey,HFValue>::Record rec;
    if ( _cache.get(cachekey, rec) )
    {
        out_hf = rec.value()._hf.get();
        out_isFallback = rec.value()._isFallback;

        if (progress)
        {
            progress->stats()["hfcache_hit_count"] += 1;
            progress->stats()["hfcache_hit_rate"] = progress->stats()["hfcache_hit_count"]/progress->stats()["hfcache_try_count"];
        }

        return true;
    }

    // Find the parent tile and start with its heightfield.
    if ( parent_hf )
    {
        TileKey parentKey = key.createParentKey();
        
        out_hf = HeightFieldUtils::createSubSample(
            parent_hf,
            parentKey.getExtent(),
            key.getExtent(),
            interp );

        if ( !out_hf.valid() && ((int)key.getLOD())-1 > _firstLOD )
        {
            // This most likely means that a parent tile expired while we were building the child.
            // No harm done in that case as this tile will soo be discarded as well.
            OE_DEBUG << "MP HFC: Unable to find tile " << key.str() << " in the live tile registry"
                << std::endl;
            return false;
        }
    }

    if ( !out_hf.valid() )
    {
        //TODO.
        // This sets the elevation tile size; query size for all tiles.
        out_hf = HeightFieldUtils::createReferenceHeightField(
            key.getExtent(), _tileSize, _tileSize, true );
    }

    bool populated = frame.populateHeightField(
        out_hf,
        key,
        true, // convertToHAE
        samplePolicy,
        progress );

    // Treat Plate Carre specially by scaling the height values. (There is no need
    // to do this with an empty heightfield)
    const MapInfo& mapInfo = frame.getMapInfo();
    if ( mapInfo.isPlateCarre() )
    {
        HeightFieldUtils::scaleHeightFieldToDegrees( out_hf.get() );
    }

    // cache it.
    HFValue cacheval;
    cacheval._hf = out_hf.get();
    cacheval._isFallback = !populated;
    _cache.insert( cachekey, cacheval );

    out_isFallback = !populated;
    return true;
}

bool
HeightFieldCache::getOrCreateHeightField(const MapFrame&                 frame,
        const TileKey&                  key,
        const osg::HeightField*         parent_hf,
        osg::ref_ptr<osg::HeightField>& out_hf,
        bool&                           out_isFallback,
        ElevationSamplePolicy           samplePolicy,
        ElevationInterpolation          interp,
        ProgressCallback*               progress )
{
    // default
    out_isFallback = false;

    // check the quick cache.
    HFKey cachekey;
    cachekey._key          = key;
    cachekey._revision     = frame.getRevision();
    cachekey._samplePolicy = samplePolicy;

    if (progress)
        progress->stats()["hfcache_try_count"] += 1;

    LRUCache<HFKey,HFValue>::Record rec;
    if ( _enabled && _cache.get(cachekey, rec) )
    {
        // Found it in the cache.
        out_hf         = rec.value()._hf.get();
        out_isFallback = rec.value()._isFallback;

        if (progress)
        {
            progress->stats()["hfcache_hit_count"] += 1;
            progress->stats()["hfcache_hit_rate"] = progress->stats()["hfcache_hit_count"]/progress->stats()["hfcache_try_count"];
        }
    }

    else
    {
        // Not in the cache, so we need to create a HF.
        TileKey parentKey = key.createParentKey();

        // Elevation "smoothing" uses the parent HF as the starting point for building
        // a new tile. This will cause lower-resolution data to propagate down the tree
        // and fill in any gaps in higher-resolution data. The result will be an elevation
        // grid that is "smoother" but not neccessarily as accurate.
        if ( _useParentAsReferenceHF && parent_hf && parentKey.valid() )
        {
            out_hf = HeightFieldUtils::createSubSample(
                         parent_hf,
                         parentKey.getExtent(),
                         key.getExtent(),
                         interp );
        }

        // If we are not smoothing, or we have no parent data, start with a basic
        // MSL=0 reference heightfield instead.
        if ( !out_hf.valid() )
        {
            out_hf = HeightFieldUtils::createReferenceHeightField( key.getExtent(), _tileSize, _tileSize, 0u );
        }

        // Next, populate it with data from the Map. The map will overwrite our starting
        // data with real data from the elevation stack.
        bool populated = frame.populateHeightField(
                             out_hf,
                             key,
                             true, // convertToHAE
                             progress );

        // If the map failed to provide any suitable data sources at all, replace the
        // heightfield with data from its parent (if available).
        if ( !populated )
        {
            if ( parentKey.valid() && parent_hf )
            {
                out_hf = HeightFieldUtils::createSubSample(
                             parent_hf,
                             parentKey.getExtent(),
                             key.getExtent(),
                             interp );
            }

            if ( !out_hf.valid() )
            {
                // NOTE: This is probably no longer be possible, but check anyway for completeness.
                return false;
            }
        }

        // ONLY cache the new heightfield if a parent HF existed. Otherwise the new HF
        // may contain invalid data. This can happen if this task runs to completion
        // while the tile's parent expires from the scene graph. In that case the result
        // of this task will be discarded. Therefore we should not cache the result here.
        // This was causing intermittent rare "flat tiles" to appear in the terrain.
        if ( _enabled && parent_hf )
        {
            // cache it.
            HFValue cacheval;
            cacheval._hf = out_hf.get();
            cacheval._isFallback = !populated;
//.........这里部分代码省略.........

void
TerrainRenderData::setup(const MapFrame& frame,
                         const RenderBindings& bindings,
                         unsigned frameNum,
                         osgUtil::CullVisitor* cv)
{
    _bindings = &bindings;

    // Create a new State object to track sampler and uniform settings
    _drawState = new DrawState();
    _drawState->_frame = frameNum;
    _drawState->_bindings = &bindings;

    // Make a drawable for each rendering pass (i.e. each render-able map layer).
    for(LayerVector::const_iterator i = frame.layers().begin();
        i != frame.layers().end();
        ++i)
    {
        Layer* layer = i->get();
        if (layer->getEnabled())
        {
            if (layer->getRenderType() == Layer::RENDERTYPE_TILE ||
                layer->getRenderType() == Layer::RENDERTYPE_PATCH)
            {
                bool render = true;

                // If this is an image layer, check the enabled/visible states.
                VisibleLayer* visLayer = dynamic_cast<VisibleLayer*>(layer);
                if (visLayer)
                {
                    render = visLayer->getVisible();
                }

                if (render)
                {
                    ImageLayer* imgLayer = dynamic_cast<ImageLayer*>(layer);

                    // Make a list of "global" layers. There are layers whose data is not
                    // represented in the TerrainTileModel, like a splatting layer or a patch
                    // layer. The data for these is dynamic and not based on data fetched.
                    if (imgLayer == 0L && layer->getRenderType() == Layer::RENDERTYPE_TILE)
                    {
                        tileLayers().push_back(layer);
                        addLayerDrawable(layer);
                    }
                    else if (layer->getRenderType() == Layer::RENDERTYPE_PATCH)
                    {
                        PatchLayer* patchLayer = static_cast<PatchLayer*>(layer); // asumption!

                        if (patchLayer->getAcceptCallback() != 0L &&
                            patchLayer->getAcceptCallback()->acceptLayer(*cv, cv->getCurrentCamera()))
                        {
                            patchLayers().push_back(dynamic_cast<PatchLayer*>(layer));
                            addLayerDrawable(layer);
                        }
                    }
                    else
                    {
                        addLayerDrawable(layer);
                    }
                }
            }
        }
    }

    // Include a "blank" layer for missing data.
    LayerDrawable* blank = addLayerDrawable(0L);
    blank->getOrCreateStateSet()->setDefine("OE_TERRAIN_RENDER_IMAGERY", osg::StateAttribute::OFF);
}

// called from the UPDATE TRAVERSAL, because this method can potentially alter
// the scene graph.
bool
StreamingTile::serviceCompletedRequests( const MapFrame& mapf, bool tileTableLocked )
{
    //Don't do anything until we have been added to the scene graph
    if (!_hasBeenTraversed) return false;

    bool tileModified = false;

    if ( !_requestsInstalled )
        return false;

    // First service the tile generator:
    if ( _tileGenRequest.valid() && _tileGenRequest->isCompleted() )
    {
        CustomTerrainTechnique* tech = dynamic_cast<CustomTerrainTechnique*>( getTerrainTechnique() );
        if ( tech )
        {
            //TODO: consider waiting to apply if there are still more tile updates in the queue.
            if ( _tileUpdates.size() == 0 )
            {
                tileModified = tech->applyTileUpdates();
            }
        }
        _tileGenRequest = 0L;
    }


    // now deal with imagery.
    const LoadingPolicy& lp = getStreamingTerrain()->getLoadingPolicy();

    StreamingTerrainNode* terrain = getStreamingTerrain();

    //Check each layer independently.
    for( ImageLayerVector::const_iterator i = mapf.imageLayers().begin(); i != mapf.imageLayers().end(); ++i )
    {
        ImageLayer* imageLayer = i->get();

        bool checkForFinalImagery = false;

        CustomColorLayer colorLayer;
        if ( getCustomColorLayer( imageLayer->getUID(), colorLayer ) )
        {
            if ( lp.mode() == LoadingPolicy::MODE_PREEMPTIVE )
            {
                // in preemptive mode, always check for the final imagery - there are no intermediate
                // placeholders.
                checkForFinalImagery = true;
            }
            else if (lp.mode() == LoadingPolicy::MODE_SEQUENTIAL && 
                     readyForNewImagery(imageLayer, colorLayer.getLevelOfDetail()) )
            {
                // in sequential mode, we have to incrementally increase imagery resolution by
                // creating placeholders based of parent tiles, one LOD at a time.
                if ( colorLayer.getLevelOfDetail() + 1 < (int)_key.getLevelOfDetail() )
                {
                    // if the parent's image LOD is higher than ours, replace ours with the parent's
                    // since it is a higher-resolution placeholder:
                    if ( _family[Relative::PARENT].getImageLOD(colorLayer.getUID()) > colorLayer.getLevelOfDetail() )
                    {
                        osg::ref_ptr<Tile> parentTile;
                        getStreamingTerrain()->getTile( _family[Relative::PARENT].tileID, parentTile, !tileTableLocked );

                        // Set the color layer to the parent color layer as a placeholder.
                        CustomColorLayer parentColorLayer;
                        if ( parentTile->getCustomColorLayer( colorLayer.getUID(), parentColorLayer ) )
                        {
                            this->setCustomColorLayer( parentColorLayer );
                        }

                        // ... and queue up an update request.
                        queueTileUpdate( TileUpdate::UPDATE_IMAGE_LAYER, colorLayer.getUID() );
                    }
                }
                else
                {
                    // we've gone as far as we can with placeholders; time to check for the
                    // final imagery tile.
                    checkForFinalImagery = true;
                }
            }
        }

        if ( checkForFinalImagery )
        {
            // Then the image requests:
            for( TaskRequestList::iterator itr = _requests.begin(); itr != _requests.end(); )
            {
                bool increment = true;
                TileColorLayerRequest* r = static_cast<TileColorLayerRequest*>( itr->get() );
                //We only care about the current layer we are checking
                if ( r->_layerUID == imageLayer->getUID() )
                {
                    if ( itr->get()->isCompleted() )
                    {
                        if ( r->wasCanceled() )
                        {
                            //Reset the cancelled task to IDLE and give it a new progress callback.
                            r->setState( TaskRequest::STATE_IDLE );
//.........这里部分代码省略.........

void
AltitudeFilter::pushAndClamp( FeatureList& features, FilterContext& cx )
{
    const Session* session = cx.getSession();

    // the map against which we'll be doing elevation clamping
    //MapFrame mapf = session->createMapFrame( Map::ELEVATION_LAYERS );
    MapFrame mapf = session->createMapFrame( 
        (Map::ModelParts)(Map::TERRAIN_LAYERS | Map::MODEL_LAYERS) );

    const SpatialReference* mapSRS = mapf.getProfile()->getSRS();
    osg::ref_ptr<const SpatialReference> featureSRS = cx.profile()->getSRS();

    // establish an elevation query interface based on the features' SRS.
    ElevationQuery eq( mapf );

    // want a result even if it's low res
    eq.setFallBackOnNoData( true );

    NumericExpression scaleExpr;
    if ( _altitude->verticalScale().isSet() )
        scaleExpr = *_altitude->verticalScale();

    NumericExpression offsetExpr;
    if ( _altitude->verticalOffset().isSet() )
        offsetExpr = *_altitude->verticalOffset();

    // whether to record the min/max height-above-terrain values.
    bool collectHATs =
        _altitude->clamping() == AltitudeSymbol::CLAMP_RELATIVE_TO_TERRAIN ||
        _altitude->clamping() == AltitudeSymbol::CLAMP_ABSOLUTE;

    // whether to clamp every vertex (or just the centroid)
    bool perVertex =
        _altitude->binding() == AltitudeSymbol::BINDING_VERTEX;

    // whether the SRS's have a compatible vertical datum.
    bool vertEquiv =
        featureSRS->isVertEquivalentTo( mapSRS );



    for( FeatureList::iterator i = features.begin(); i != features.end(); ++i )
    {
        Feature* feature = i->get();
        
        // run a symbol script if present.
        if ( _altitude.valid() && _altitude->script().isSet() )
        {
            StringExpression temp( _altitude->script().get() );
            feature->eval( temp, &cx );
        }

        double maxTerrainZ  = -DBL_MAX;
        double minTerrainZ  =  DBL_MAX;
        double minHAT       =  DBL_MAX;
        double maxHAT       = -DBL_MAX;

        double scaleZ = 1.0;
        if ( _altitude.valid() && _altitude->verticalScale().isSet() )
            scaleZ = feature->eval( scaleExpr, &cx );

        double offsetZ = 0.0;
        if ( _altitude.valid() && _altitude->verticalOffset().isSet() )
            offsetZ = feature->eval( offsetExpr, &cx );
        
        GeometryIterator gi( feature->getGeometry() );
        while( gi.hasMore() )
        {
            Geometry* geom = gi.next();

            // Absolute heights in Z. Only need to collect the HATs; the geometry
            // remains unchanged.
            if ( _altitude->clamping() == AltitudeSymbol::CLAMP_ABSOLUTE )
            {
                if ( perVertex )
                {
                    std::vector<double> elevations;
                    elevations.reserve( geom->size() );

                    if ( eq.getElevations( geom->asVector(), featureSRS, elevations, _maxRes ) )
                    {
                        for( unsigned i=0; i<geom->size(); ++i )
                        {
                            osg::Vec3d& p = (*geom)[i];

                            p.z() *= scaleZ;
                            p.z() += offsetZ;

                            double z = p.z();

                            if ( !vertEquiv )
                            {
                                osg::Vec3d tempgeo;
                                if ( !featureSRS->transform(p, mapSRS->getGeographicSRS(), tempgeo) )
                                    z = tempgeo.z();
                            }

                            double hat = z - elevations[i];

//.........这里部分代码省略.........