void minkowskiSum( const Geometry& gA, const Polygon_2& gB, CGAL::Polygon_set_2< Kernel > & polygonSet )
{
if ( gA.isEmpty() )
return ;
switch ( gA.geometryTypeId() ){
case TYPE_POINT:
return minkowskiSum( gA.as< Point >(), gB, polygonSet ) ;
case TYPE_LINESTRING:
return minkowskiSum( gA.as< LineString >(), gB, polygonSet ) ;
case TYPE_POLYGON:
return minkowskiSum( gA.as< Polygon >(), gB, polygonSet ) ;
case TYPE_TRIANGLE:
return minkowskiSum( gA.as< Triangle >().toPolygon(), gB, polygonSet ) ;
case TYPE_SOLID:
return minkowskiSum( gA.as< Solid >(), gB, polygonSet ) ;
case TYPE_MULTIPOINT:
case TYPE_MULTILINESTRING:
case TYPE_MULTIPOLYGON:
case TYPE_MULTISOLID:
case TYPE_GEOMETRYCOLLECTION:
case TYPE_TRIANGULATEDSURFACE:
case TYPE_POLYHEDRALSURFACE:
return minkowskiSumCollection( gA, gB, polygonSet ) ;
}
BOOST_THROW_EXCEPTION(Exception(
( boost::format("minkowskiSum( %s, 'Polygon' ) is not defined")
% gA.geometryType() ).str()
));
}
std::auto_ptr< Geometry > minkowskiSum( const Geometry& gA, const Polygon& gB )
{
SFCGAL_ASSERT_GEOMETRY_VALIDITY_2D( gA );
SFCGAL_ASSERT_GEOMETRY_VALIDITY_2D( gB );
return minkowskiSum( gA, gB, NoValidityCheck() );
}
std::auto_ptr< Geometry > minkowskiSum( const Geometry& gA, const Polygon& gB, NoValidityCheck )
{
if ( gB.isEmpty() ) {
return std::auto_ptr< Geometry >( gA.clone() );
}
Polygon_set_2 polygonSet ;
minkowskiSum( gA, gB.toPolygon_2(), polygonSet ) ;
return std::auto_ptr< Geometry >( detail::polygonSetToMultiPolygon( polygonSet ).release() ) ;
}
void minkowskiSum( const Polygon& gA, const Polygon_2& gB, Polygon_set_2& polygonSet )
{
if ( gA.isEmpty() ) {
return ;
}
/*
* Invoke minkowski_sum_2 for exterior ring
*/
{
Polygon_with_holes_2 sum = minkowski_sum_2( gA.exteriorRing().toPolygon_2(), gB ) ;
if ( polygonSet.is_empty() ) {
polygonSet.insert( sum );
}
else {
polygonSet.join( sum );
}
}
/*
* Compute the Minkowski sum for each segment of the interior rings
* and perform the union of the result. The result is a polygon, and its holes
* correspond to the inset.
*
*/
if ( gA.hasInteriorRings() ) {
Polygon_set_2 sumInteriorRings ;
for ( size_t i = 0; i < gA.numInteriorRings(); i++ ) {
minkowskiSum( gA.interiorRingN( i ), gB, sumInteriorRings ) ;
}
/*
* compute the difference for each hole of the resulting polygons
*/
std::list<Polygon_with_holes_2> interiorPolygons ;
sumInteriorRings.polygons_with_holes( std::back_inserter( interiorPolygons ) ) ;
for ( std::list<Polygon_with_holes_2>::iterator it_p = interiorPolygons.begin();
it_p != interiorPolygons.end(); ++it_p ) {
for ( Polygon_with_holes_2::Hole_iterator it_hole = it_p->holes_begin();
it_hole != it_p->holes_end(); ++it_hole ) {
it_hole->reverse_orientation() ;
polygonSet.difference( *it_hole ) ;
} // foreach hole
}// foreach polygon
}
}
void minkowskiSumCollection( const Geometry& gA, const Polygon_2& gB, Polygon_set_2& polygonSet )
{
for ( size_t i = 0; i < gA.numGeometries(); i++ ) {
minkowskiSum( gA.geometryN( i ), gB, polygonSet );
}
}
std::auto_ptr< MultiPolygon > minkowskiSum( const Geometry& gA, const Polygon& gB )
{
Polygon_set_2 polygonSet ;
minkowskiSum( gA, gB.toPolygon_2(), polygonSet ) ;
return detail::polygonSetToMultiPolygon( polygonSet ) ;
}
