Inheritance diagram for osgEarth::Features::FeatureGridder:

Collaboration diagram for osgEarth::Features::FeatureGridder:

Public Member Functions
	FeatureGridder (const Bounds &bounds, const GriddingPolicy &policy)
int	getNumCells () const
bool	getCellBounds (int i, Bounds &output) const
bool	cullFeatureListToCell (int i, FeatureList &features) const
virtual	~FeatureGridder ()
Static Public Member Functions
static bool	isSupported ()
Protected Attributes
Bounds	_inputBounds
GriddingPolicy	_policy
int	_cellsX
int	_cellsY
std::list< void * >	_geosGeoms

Detailed Description

Given a list of features, this will grid them up and return one grid cell at a time. For each grid cell, it will crop the feature geometry to the cell boundary.

Definition at line 88 of file FeatureGridder.

Constructor & Destructor Documentation

FeatureGridder::FeatureGridder	(	const Bounds &	bounds,
		const GriddingPolicy &	policy
	)

Definition at line 87 of file FeatureGridder.cpp.

                                                              :
_inputBounds( inputBounds ),
_policy( policy )
{
    if ( _policy.enabled() ) //_policy.cellSize().isSet() && *_policy.cellSize() > 0.0 )
    {
        _cellsX = (int)::ceil(_inputBounds.width() / *_policy.cellSize() );
        _cellsY = (int)::ceil(_inputBounds.height() / *_policy.cellSize() );
    }
    else
    {
        _cellsX = 1;
        _cellsY = 1;
    }

    _cellsX = osg::clampAbove( _cellsX, 1 );
    _cellsY = osg::clampAbove( _cellsY, 1 );

#ifndef OSGEARTH_HAVE_GEOS

    if ( _policy.cullingTechnique().isSetTo( GriddingPolicy::CULL_BY_CROPPING ) )
    {
        OE_WARN 
            << "Warning: Gridding policy 'cull by cropping' requires GEOS. Falling back on 'cull by centroid'." 
            << std::endl;

        _policy.cullingTechnique() = GriddingPolicy::CULL_BY_CENTROID;
    }

#endif // !OSGEARTH_HAVE_GEOS
}

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FeatureGridder::~FeatureGridder ( ) [virtual]

Definition at line 120 of file FeatureGridder.cpp.

{
    //nop
}

Member Function Documentation

bool FeatureGridder::cullFeatureListToCell	(	int	i,
		FeatureList &	features
	)		const

Definition at line 151 of file FeatureGridder.cpp.

{
    bool success = true;
    int inCount = features.size();

    Bounds b;
    if ( getCellBounds( i, b ) )
    {
        if ( _policy.cullingTechnique() == GriddingPolicy::CULL_BY_CENTROID )
        {
            for( FeatureList::iterator f_i = features.begin(); f_i != features.end();  )
            {
                bool keepFeature = false;

                Feature* feature = f_i->get();
                Symbology::Geometry* featureGeom = feature->getGeometry();
                if ( featureGeom )
                {
                    osg::Vec3d centroid = featureGeom->getBounds().center();
                    if ( b.contains( centroid.x(), centroid.y() ) )
                    {
                        keepFeature = true;
                    }
                }

                if ( keepFeature )
                    ++f_i;
                else
                    f_i = features.erase( f_i );
            }
        }

        else // CULL_BY_CROPPING (requires GEOS)
        {

#ifdef OSGEARTH_HAVE_GEOS

            // create the intersection polygon:
            osg::ref_ptr<Symbology::Polygon> poly = new Symbology::Polygon( 4 );
            poly->push_back( osg::Vec3d( b.xMin(), b.yMin(), 0 ));
            poly->push_back( osg::Vec3d( b.xMax(), b.yMin(), 0 ));
            poly->push_back( osg::Vec3d( b.xMax(), b.yMax(), 0 ));
            poly->push_back( osg::Vec3d( b.xMin(), b.yMax(), 0 ));

            for( FeatureList::iterator f_i = features.begin(); f_i != features.end();  )
            {
                bool keepFeature = false;

                Feature* feature = f_i->get();
                Symbology::Geometry* featureGeom = feature->getGeometry();
                if ( featureGeom )
                {
                    osg::ref_ptr<Symbology::Geometry> croppedGeometry;
                    if ( featureGeom->crop( poly.get(), croppedGeometry ) )
                    {
                        feature->setGeometry( croppedGeometry.get() );
                        keepFeature = true;
                    }                   
                }

                if ( keepFeature )
                    ++f_i;
                else
                    f_i = features.erase( f_i );
            }  

#endif // OSGEARTH_HAVE_GEOS

        }

    }

    OE_INFO << LC
            << "Grid cell " << i << ": bounds="
            << b.xMin() << "," << b.yMin() << " => " << b.xMax() << "," << b.yMax()
            << "; in=" << inCount << "; out=" << features.size()
            << std::endl;

    return success;
}

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bool FeatureGridder::getCellBounds	(	int	i,
		Bounds &	output
	)		const

Definition at line 132 of file FeatureGridder.cpp.

{
    if ( i >= 0 && i < (_cellsX*_cellsY) )
    {
        int x = i % _cellsX;
        int y = i / _cellsX;

        double xmin = _inputBounds.xMin() + _policy.cellSize().value()  * (double)x;
        double ymin = _inputBounds.yMin() + _policy.cellSize().value() * (double)y;
        double xmax = osg::clampBelow( _inputBounds.xMin() + *_policy.cellSize() * (double)(x+1), _inputBounds.xMax() );
        double ymax = osg::clampBelow( _inputBounds.yMin() + *_policy.cellSize() * (double)(y+1), _inputBounds.yMax() );

        output = Bounds( xmin, ymin, xmax, ymax );
        return true;
    }
    return false;
}