geos::operation::relateng::PolygonNodeConverter Class Reference

#include <PolygonNodeConverter.h>

Static Public Member Functions
static std::vector< std::unique_ptr< NodeSection > >	convert (std::vector< const NodeSection * > &polySections)

Detailed Description

Converts the node sections at a polygon node where a shell and one or more holes touch, or two or more holes touch. This converts the node topological structure from the OGC "touching-rings" (AKA "minimal-ring") model to the equivalent "self-touch" (AKA "inverted/exverted ring" or "maximal ring") model. In the "self-touch" model the converted NodeSection corners enclose areas which all lies inside the polygon (i.e. they does not enclose hole edges). This allows RelateNode to use simple area-additive semantics for adding edges and propagating edge locations.

The input node sections are assumed to have canonical orientation (CW shells and CCW holes). The arrangement of shells and holes must be topologically valid. Specifically, the node sections must not cross or be collinear.

This supports multiple shell-shell touches (including ones containing holes), and hole-hole touches, This generalizes the relate algorithm to support both the OGC model and the self-touch model.

Author

Martin Davis

See also

RelateNode

Member Function Documentation

convert()

static std::vector< std::unique_ptr< NodeSection > > geos::operation::relateng::PolygonNodeConverter::convert ( std::vector< const NodeSection * > &  polySections )

static

Converts a list of sections of valid polygon rings to have "self-touching" structure. There are the same number of output sections as input ones.

Parameters

polySections

the original sections

Returns

the converted sections

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The documentation for this class was generated from the following file:

• PolygonNodeConverter.h