C++ EngineContext::getUnloader方法代码示例

void TileNode::cull(osg::NodeVisitor& nv)
{
    osgUtil::CullVisitor* cv = static_cast<osgUtil::CullVisitor*>( &nv );

    EngineContext* context = static_cast<EngineContext*>( nv.getUserData() );
    const SelectionInfo& selectionInfo = context->getSelectionInfo();

    // record the number of drawables before culling this node:
    unsigned before = RenderBinUtils::getTotalNumRenderLeaves( cv->getRenderStage() );

    if ( context->progress() )
        context->progress()->stats()["TileNode::cull"]++;

    // determine whether we can and should subdivide to a higher resolution:
    bool subdivide = shouldSubDivide(nv, selectionInfo, cv->getLODScale());

    // whether it is OK to create child TileNodes is necessary.
    bool canCreateChildren = subdivide;

    // whether it is OK to load data if necessary.
    bool canLoadData = true;


    if ( _dirty && context->getOptions().progressive() == true )
    {
        // Don't create children in progressive mode until content is in place
        canCreateChildren = false;
    }
    
    // If this is an inherit-viewpoint camera, we don't need it to invoke subdivision
    // because we want only the tiles loaded by the true viewpoint.
    const osg::Camera* cam = cv->getCurrentCamera();
    if ( cam && cam->getReferenceFrame() == osg::Camera::ABSOLUTE_RF_INHERIT_VIEWPOINT )
    {
        canCreateChildren = false;
        canLoadData = false;
    }

    optional<bool> surfaceVisible( false );

    if (subdivide)
    {
        // We are in range of the child nodes. Either draw them or load them.

        // If the children don't exist, create them and inherit the parent's data.
        if ( getNumChildren() == 0 && canCreateChildren )
        {
            Threading::ScopedMutexLock exclusive(_mutex);
            if ( getNumChildren() == 0 )
            {
                createChildren( context );
            }
        }

        // If all are ready, traverse them now.
        if ( getNumChildren() == 4 )
        {
            for(int i=0; i<4; ++i)
            {
                // pre-check each child for simple bounding sphere culling, and if the check 
                // fails, unload it's children if them exist. This lets us unload dormant
                // tiles from memory as we go. If those children are visible from another
                // camera, no worries, the unload attempt will fail gracefully.
                if (!cv->isCulled(*_children[i].get()))
                {
                    _children[i]->accept( nv );
                }
                else
                {
                    context->getUnloader()->unloadChildren(getSubTile(i)->getTileKey());
                }
            }
        }

        // If we don't traverse the children, traverse this node's payload.
        else if ( _surface.valid() )
        {
            surfaceVisible = acceptSurface( cv, context );
        }
    }

    // If children are outside camera range, draw the payload and expire the children.
    else if ( _surface.valid() )
    {
        surfaceVisible = acceptSurface( cv, context );

        // if children exists, and are not in the process of loading, unload them now.
        if ( !_dirty && _children.size() > 0 )
        {
            context->getUnloader()->unloadChildren( this->getTileKey() );
        }
    }

    // See whether we actually added any drawables.
    unsigned after = RenderBinUtils::getTotalNumRenderLeaves( cv->getRenderStage() );
    bool addedDrawables = (after > before);
    
    // Only continue if we accepted at least one surface drawable.
    if ( addedDrawables )
    {
//.........这里部分代码省略.........