geos::operation::buffer::OffsetSegmentGenerator Class Reference

#include <OffsetSegmentGenerator.h>

Public Member Functions
	OffsetSegmentGenerator (const geom::PrecisionModel *newPrecisionModel, const BufferParameters &bufParams, double distance)
bool	hasNarrowConcaveAngle () const
void	initSideSegments (const geom::Coordinate &nS1, const geom::Coordinate &nS2, int nSide)
void	getCoordinates (std::vector< geom::CoordinateSequence * > &to)
void	closeRing ()
void	createCircle (const geom::Coordinate &p, double distance)
	Adds a CW circle around a point.
void	createSquare (const geom::Coordinate &p, double distance)
	Adds a CW square around a point.
void	addFirstSegment ()
	Add first offset point.
void	addLastSegment ()
	Add last offset point.
void	addNextSegment (const geom::Coordinate &p, bool addStartPoint)
void	addLineEndCap (const geom::Coordinate &p0, const geom::Coordinate &p1)
	Add an end cap around point p1, terminating a line segment coming from p0.
void	addSegments (const geom::CoordinateSequence &pts, bool isForward)

Static Public Member Functions
static void	computeOffsetSegment (const geom::LineSegment &seg, int side, double distance, geom::LineSegment &offset)
	Compute an offset segment for an input segment on a given side and at a given distance. More...

Detailed Description

Generates segments which form an offset curve. Supports all end cap and join options provided for buffering. Implements various heuristics to produce smoother, simpler curves which are still within a reasonable tolerance of the true curve.

Author

Martin Davis

Member Function Documentation

computeOffsetSegment()

static void geos::operation::buffer::OffsetSegmentGenerator::computeOffsetSegment ( const geom::LineSegment &  seg, int  side, double  distance, geom::LineSegment &  offset  )

static

Compute an offset segment for an input segment on a given side and at a given distance.

The offset points are computed in full double precision, for accuracy.

Parameters

seg	the segment to offset
side	the side of the segment the offset lies on
distance	the offset distance
offset	the points computed for the offset segment

getCoordinates()

void geos::operation::buffer::OffsetSegmentGenerator::getCoordinates ( std::vector< geom::CoordinateSequence * > &  to )

inline

Get coordinates by taking ownership of them

After this call, the coordinates reference in this object are dropped. Calling twice will segfault...

FIXME: refactor memory management of this

hasNarrowConcaveAngle()

bool geos::operation::buffer::OffsetSegmentGenerator::hasNarrowConcaveAngle ( ) const

inline

Tests whether the input has a narrow concave angle (relative to the offset distance). In this case the generated offset curve will contain self-intersections and heuristic closing segments. This is expected behaviour in the case of buffer curves. For pure offset curves, the output needs to be further treated before it can be used.

Returns

true if the input has a narrow concave angle

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

• OffsetSegmentGenerator.h