Eli Packer, Leo Valque

Snap Rounding is a well known method for converting arbitrary-precision arrangements of segments into a smaller precision representation. This package supports methods to converting into various including fixed-precision or floating-point representation.

Introduced in: CGAL 3.1
Depends on: 2D Arrangements
BibTeX: cgal:p-sr2-26a
License: GPL
Windows Demo: 2D Snap Rounding

Classified Reference Pages

Parameters

Optional parameters of the functions of this package are implemented as Named Parameters. The page Named Parameters describes their usage.

Snap Rounding Common

CGAL::snap_rounding_2()

Vertical Slab Snap Rounding

Hot Pixel Snap Rounding

Snap Rounding Concepts

Modules
	Concepts

Classes
struct	CGAL::Double_grid_snap_rounding_traits_2< InputKernel, ExactKernel, BaseTraits >
	The class `Double_grid_snap_rounding_traits_2<InputKernel, ExactKernel, BaseTraits>` is a model of the `VerticalSlabSnapRoundingTraits_2` concept. More...

struct	CGAL::Float_grid_snap_rounding_traits_2< InputKernel, ExactKernel, BaseTraits >
	The class `Float_grid_snap_rounding_traits_2<InputKernel, ExactKernel, BaseTraits>` is a model of the `VerticalSlabSnapRoundingTraits_2` concept. More...

class	CGAL::Hot_pixel_snap_rounding_traits_2< BaseKernel >
	The class `Hot_pixel_snap_rounding_traits_2<Kernel>` is a model of the `HotPixelSnapRoundingTraits_2` concept. More...

struct	CGAL::Integer_grid_snap_rounding_traits_2< InputKernel, ExactKernel, BaseTraits >
	The class `Integer_grid_snap_rounding_traits_2<InputKernel, ExactKernel, BaseTraits>` is a model of the `VerticalSlabSnapRoundingTraits_2` concept. More...

Functions
template<class SegmentRange , class OutputPolylineIterator , class NamedParameters = parameters::Default_named_parameters>
OutputPolylineIterator	CGAL::hot_pixel_snap_rounding_2 (const SegmentRange &segments, OutputPolylineIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

template<class SegmentRange , class OutputSegmentIterator , class NamedParameters = parameters::Default_named_parameters>
OutputSegmentIterator	CGAL::hot_pixel_snap_rounding_2 (const SegmentRange &segments, OutputSegmentIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

template<class PolygonRange , class OutputPolygonIterator , class NamedParameters = parameters::Default_named_parameters>
OutputPolygonIterator	CGAL::hot_pixel_snap_rounding_2 (PolygonRange &polygons, OutputPolygonIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of polygons so that their boundary segments are pairwise disjoint in their interiors.

template<class Traits , class InputIterator , class OutputContainer >
void	CGAL::snap_rounding_2 (InputIterator begin, InputIterator end, OutputContainer &output_container, typename Traits::NT pixel_size, bool do_isr=true, bool int_output=true, unsigned int number_of_kd_trees=1)

template<class SegmentRange , class OutputPolylineIterator , class NamedParameters = parameters::Default_named_parameters>
OutputPolylineIterator	CGAL::snap_rounding_2 (const SegmentRange &segments, OutputPolylineIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

template<class SegmentRange , class OutputSegmentIterator , class NamedParameters = parameters::Default_named_parameters>
OutputSegmentIterator	CGAL::snap_rounding_2 (const SegmentRange &segments, OutputSegmentIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

template<class PolygonRange , class OutputPolygonIterator , class NamedParameters = parameters::Default_named_parameters>
OutputPolygonIterator	CGAL::snap_rounding_2 (PolygonRange &polygons, OutputPolygonIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of polygons so that their boundary segments are pairwise disjoint in their interiors.

template<class SegmentRange , class OutputPolylineIterator , class NamedParameters = parameters::Default_named_parameters>
OutputPolylineIterator	CGAL::vertical_slab_snap_rounding_2 (const SegmentRange &segments, OutputPolylineIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

template<class SegmentRange , class OutputSegmentIterator , class NamedParameters = parameters::Default_named_parameters>
OutputSegmentIterator	CGAL::vertical_slab_snap_rounding_2 (const SegmentRange &segments, OutputSegmentIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

template<class PolygonRange , class OutputPolygonIterator , class NamedParameters = parameters::Default_named_parameters>
OutputPolygonIterator	CGAL::vertical_slab_snap_rounding_2 (PolygonRange &polygons, OutputPolygonIterator out, const NamedParameters &np=parameters::default_values())
	subdivides and rounds a range of polygons so that their boundary segments are pairwise disjoint in their interiors.

Function Documentation

◆ hot_pixel_snap_rounding_2() [1/3]

template<class SegmentRange , class OutputPolylineIterator , class NamedParameters = parameters::Default_named_parameters>

OutputPolylineIterator CGAL::hot_pixel_snap_rounding_2	(	const SegmentRange &	segments,
		OutputPolylineIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/hot_pixel_snap_rounding_2.h>

subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

The output is a range of polylines, where each polyline corresponds to an input segment.

Template Parameters

SegmentRange	a range of `Kernel::Segment_2`, model of Range. Its iterator type is InputIterator.
OutputPolylineIterator	model of OutputIterator holding `Polyline`. `Polyline` must be a type that provides a `push_back(Point_2)` function.
NamedParameters	a sequence of Named Parameters

Parameters

segments	the input segment range
out	the output inserter
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

The size of the pixel. The plane will be tiled with square pixels of that width such that the origin is the center of a pixel. Type: `GT::FT` Default: FT(1.)
determines whether to apply Iterative Snap Rounding, see the user manual for more details. Type: Boolean Default: true
If set to true, the output coordinates are expressed in the integer grid (pixel indices). Otherwise, they are given in the input coordinate system. Type: Boolean Default: true
an instance of a geometric traits class Type: The traits class must respect the concept of `HotPixelSnapRoundingTraits_2` Default: an instance of `CGAL::Hot_pixel_snap_rounding_traits_2`

Examples: Snap_rounding_2/iterative_snap_rounding.cpp, and Snap_rounding_2/snap_rounding_to_integer.cpp.

◆ hot_pixel_snap_rounding_2() [2/3]

template<class SegmentRange , class OutputSegmentIterator , class NamedParameters = parameters::Default_named_parameters>

OutputSegmentIterator CGAL::hot_pixel_snap_rounding_2	(	const SegmentRange &	segments,
		OutputSegmentIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/hot_pixel_snap_rounding_2.h>

subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

The output is a range of segments.

Template Parameters

SegmentRange	a range of `Kernel::Segment_2`, model of Range. Its iterator type is InputIterator.
OutputSegmentIterator	model of OutputIterator holding `Kernel::Segment_2`
NamedParameters	a sequence of Named Parameters

Parameters

segments	the input segment range
out	the output inserter
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

The size of the pixel. The plane will be tiled with square pixels of that width such that the origin is the center of a pixel. Type: `GT::FT` Default: FT(1.)
determines whether to apply Iterative Snap Rounding, see the user manual for more details. Type: Boolean Default: true
If set to true, the output coordinates are expressed in the integer grid (pixel indices). Otherwise, they are given in the input coordinate system. Type: Boolean Default: true
an instance of a geometric traits class Type: The traits class must respect the concept of `HotPixelSnapRoundingTraits_2` Default: an instance of `CGAL::Hot_pixel_snap_rounding_traits_2`

◆ hot_pixel_snap_rounding_2() [3/3]

template<class PolygonRange , class OutputPolygonIterator , class NamedParameters = parameters::Default_named_parameters>

OutputPolygonIterator CGAL::hot_pixel_snap_rounding_2	(	PolygonRange &	polygons,
		OutputPolygonIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/hot_pixel_snap_rounding_2.h>

subdivides and rounds a range of polygons so that their boundary segments are pairwise disjoint in their interiors.

If the input polygons are disjoint, the output polygons remain non-overlapping, although they may share vertices or edges. Each output polygon is free of self-intersections but may present pinched sections.

Template Parameters

PolygonRange	a range of `CGAL::Polygon_2`, model of Range. Its iterator type is InputIterator.
OutputPolygonIterator	model of OutputIterator holding `CGAL::Polygon_2`
NamedParameters	a sequence of Named Parameters

Parameters

polygons	the range of input polygons
out	the output inserter
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

The size of the pixel. The plane will be tiled with square pixels of that width such that the origin is the center of a pixel. Type: `GT::FT` Default: FT(1.)
determines whether to apply Iterative Snap Rounding, see the user manual for more details. Type: Boolean Default: true
If set to true, the output coordinates are expressed in the integer grid (pixel indices). Otherwise, they are given in the input coordinate system. Type: Boolean Default: true
an instance of a geometric traits class Type: The traits class must respect the concept of `HotPixelSnapRoundingTraits_2` Default: an instance of `CGAL::Hot_pixel_snap_rounding_traits_2`

Warning: a convex input polygon might no longer be convex after rounding.

◆ snap_rounding_2() [1/4]

template<class SegmentRange , class OutputPolylineIterator , class NamedParameters = parameters::Default_named_parameters>

OutputPolylineIterator CGAL::snap_rounding_2	(	const SegmentRange &	segments,
		OutputPolylineIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/Snap_rounding_2.h>

subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

The output is a range of polylines, where each polyline corresponds to an input segment.

calls the function CGAL::vertical_slab_snap_rounding_2() or CGAL::hot_pixel_snap_rounding_2() depending if geom_traits is model of VerticalSlabSnapRoundingTraits_2 or HotPixelSnapRoundingTraits_2.

Template Parameters

SegmentRange	a range of `Kernel::Segment_2`, model of Range. Its iterator type is InputIterator.
OutputPolylineIterator	model of OutputIterator holding `Polyline`. `Polyline` must be a type that provides a `push_back(Point_2)` function.
NamedParameters	a sequence of Named Parameters

Parameters

segments	the input segment range
out	the output inserter
np	an optional sequence of Named Parameters including the one listed below

Optional Named Parameters

an instance of a geometric traits class
Type: The traits class must respect the concept of VerticalSlabSnapRoundingTraits_2 or HotPixelSnapRoundingTraits_2
Default: an instance of CGAL::Double_grid_snap_rounding_traits_2

◆ snap_rounding_2() [2/4]

template<class SegmentRange , class OutputSegmentIterator , class NamedParameters = parameters::Default_named_parameters>

OutputSegmentIterator CGAL::snap_rounding_2	(	const SegmentRange &	segments,
		OutputSegmentIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/Snap_rounding_2.h>

subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

The output is a range of segments.

calls the function CGAL::vertical_slab_snap_rounding_2() or CGAL::hot_pixel_snap_rounding_2() depending if the parameter geom_traits is model of VerticalSlabSnapRoundingTraits_2 or HotPixelSnapRoundingTraits_2.

Template Parameters

SegmentRange	a range of `Kernel::Segment_2`, model of Range. Its iterator type is InputIterator.
OutputSegmentIterator	model of OutputIterator holding `Kernel::Segment_2`
NamedParameters	a sequence of Named Parameters

Parameters

segments	the input segment range
out	the output inserter
np	an optional sequence of Named Parameters including the one listed below

Optional Named Parameters

an instance of a geometric traits class
Type: The traits class must respect the concept of VerticalSlabSnapRoundingTraits_2 or HotPixelSnapRoundingTraits_2
Default: an instance of CGAL::Double_grid_snap_rounding_traits_2

◆ snap_rounding_2() [3/4]

template<class Traits , class InputIterator , class OutputContainer >

void CGAL::snap_rounding_2	(	InputIterator	begin,
		InputIterator	end,
		OutputContainer &	output_container,
		typename Traits::NT	pixel_size,
		bool	do_isr = `true`,
		bool	int_output = `true`,
		unsigned int	number_of_kd_trees = `1`
	)

#include <CGAL/Snap_rounding_2.h>

Deprecated:: use newer API of CGAL::snap_rounding_2() or CGAL::hot_pixel_snap_rounding_2()

Template Parameters

Traits	must be a model of `HotPixelSnapRoundingTraits_2`.
InputIterator	must be an iterator with value type `Traits::Segment_2`.
OutputContainer	must be a container with a method `push_back(const OutputContainer::value_type& c)`, where `OutputContainer::value_type` must be a container with a method `push_back(const Traits::Point_2& p)`

Parameters

begin,end	The first two parameters denote the iterator range of the input segments.
output_container	is a reference to a container of the output polylines. Since a polyline is composed of a sequence of points, a polyline is a container itself.
do_isr	The fifth parameter determines whether to apply ISR or SR.
pixel_size	The fourth parameter denotes the pixel size `w`. The plane will be tiled with square pixels of width `w` such that the origin is the center of a pixel. `pixel_size` must have a positive value.
int_output	If set to true, the output coordinates are expressed in the integer grid (pixel indices). Otherwise, they are given in the input coordinate system.
number_of_kd_trees	The seventh parameter is briefly described later on this page; for a detailed description see [3].

Examples: Snap_rounding_2/snap_rounding_to_double.cpp.

◆ snap_rounding_2() [4/4]

template<class PolygonRange , class OutputPolygonIterator , class NamedParameters = parameters::Default_named_parameters>

OutputPolygonIterator CGAL::snap_rounding_2	(	PolygonRange &	polygons,
		OutputPolygonIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/Snap_rounding_2.h>

subdivides and rounds a range of polygons so that their boundary segments are pairwise disjoint in their interiors.

If the input polygons are disjoint, the output polygons remain non-overlapping, although they may share vertices or edges. Each output polygon is free of self-intersections but may present pinched sections.

Per default, this function rounds on double precision coordinates using CGAL::vertical_slab_snap_rounding_2(). Other rounding schemes or methods can be used by providing a geom_traits that is model of VerticalSlabSnapRoundingTraits_2 or HotPixelSnapRoundingTraits_2.

Template Parameters

PolygonRange	a range of `CGAL::Polygon_2`, model of Range. Its iterator type is InputIterator.
OutputPolygonIterator	model of OutputIterator holding `CGAL::Polygon_2`
NamedParameters	a sequence of Named Parameters

Parameters

polygons	the range of input polygons
out	the output inserter
np	an optional sequence of Named Parameters including the one listed below

Optional Named Parameters

an instance of a geometric traits class
Type: The traits class must respect the concept of VerticalSlabSnapRoundingTraits_2
Default: an instance of CGAL::Double_grid_snap_rounding_traits_2

Warning: a convex input polygon might no longer be convex after rounding.

◆ vertical_slab_snap_rounding_2() [1/3]

template<class SegmentRange , class OutputPolylineIterator , class NamedParameters = parameters::Default_named_parameters>

OutputPolylineIterator CGAL::vertical_slab_snap_rounding_2	(	const SegmentRange &	segments,
		OutputPolylineIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/vertical_slab_snap_rounding_2.h>

subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

The output is a range of polylines, where each polyline corresponds to an input segment.

Template Parameters

SegmentRange	a range of `Kernel::Segment_2`, model of Range. Its iterator type is InputIterator.
OutputPolylineIterator	model of OutputIterator holding `Polyline`. `Polyline` must be a type that provides a `push_back(Point_2)` function.
NamedParameters	a sequence of Named Parameters

Parameters

segments	the input segment range
out	the output inserter
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

an instance of a geometric traits class
Type: The traits class must respect the concept of VerticalSlabSnapRoundingTraits_2
Default: an instance of CGAL::Double_grid_snap_rounding_traits_2

◆ vertical_slab_snap_rounding_2() [2/3]

template<class SegmentRange , class OutputSegmentIterator , class NamedParameters = parameters::Default_named_parameters>

OutputSegmentIterator CGAL::vertical_slab_snap_rounding_2	(	const SegmentRange &	segments,
		OutputSegmentIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/vertical_slab_snap_rounding_2.h>

subdivides and rounds a range of segments so that they are pairwise disjoint in their interiors.

The output is a range of segments.

Template Parameters

SegmentRange	a range of `Kernel::Segment_2`, model of Range. Its iterator type is InputIterator.
OutputSegmentIterator	model of OutputIterator holding `Kernel::Segment_2`
NamedParameters	a sequence of Named Parameters

Parameters

segments	the input segment range
out	the output inserter
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

an instance of a geometric traits class
Type: The traits class must respect the concept of VerticalSlabSnapRoundingTraits_2
Default: an instance of CGAL::Double_grid_snap_rounding_traits_2

◆ vertical_slab_snap_rounding_2() [3/3]

template<class PolygonRange , class OutputPolygonIterator , class NamedParameters = parameters::Default_named_parameters>

OutputPolygonIterator CGAL::vertical_slab_snap_rounding_2	(	PolygonRange &	polygons,
		OutputPolygonIterator	out,
		const NamedParameters &	np = `parameters::default_values()`
	)

#include <CGAL/vertical_slab_snap_rounding_2.h>

subdivides and rounds a range of polygons so that their boundary segments are pairwise disjoint in their interiors.

If the input polygons are disjoint, the output polygons remain non-overlapping, although they may share vertices or edges. Each output polygon is free of self-intersections but may present pinched sections.

Template Parameters

PolygonRange	a range of `CGAL::Polygon_2`, model of Range. Its iterator type is InputIterator.
OutputPolygonIterator	model of OutputIterator holding `CGAL::Polygon_2`
NamedParameters	a sequence of Named Parameters

Parameters

polygons	the range of input polygons
out	the output inserter
np	an optional sequence of Named Parameters among the ones listed below

Optional Named Parameters

an instance of a geometric traits class
Type: The traits class must respect the concept of VerticalSlabSnapRoundingTraits_2
Default: an instance of CGAL::Double_grid_snap_rounding_traits_2

Warning: a convex input polygon might no longer be convex after rounding.

Classified Reference Pages

Parameters

Snap Rounding Common

Vertical Slab Snap Rounding

Hot Pixel Snap Rounding

Snap Rounding Concepts

Modules

Classes

Functions

Function Documentation

◆ hot_pixel_snap_rounding_2() [1/3]

◆ hot_pixel_snap_rounding_2() [2/3]

◆ hot_pixel_snap_rounding_2() [3/3]

◆ snap_rounding_2() [1/4]

◆ snap_rounding_2() [2/4]

◆ snap_rounding_2() [3/4]

◆ snap_rounding_2() [4/4]

◆ vertical_slab_snap_rounding_2() [1/3]

◆ vertical_slab_snap_rounding_2() [2/3]

◆ vertical_slab_snap_rounding_2() [3/3]