Aleph::GeomPolygonUtils Class Reference

Shared polygon helpers used across multiple geometry algorithms. More...

#include <geom_algorithms.H>

Static Public Member Functions
static Array< Point >	extract_vertices (const Polygon &poly)
	Extract vertices from a polygon into an array for indexed access.
static Geom_Number	signed_double_area (const Array< Point > &verts)
	Compute twice the signed area (shoelace formula without division).
static Geom_Number	signed_double_area (const Polygon &poly)
	Compute twice the signed area of a polygon.
static Geom_Number	signed_area (const Array< Point > &verts)
	Compute the actual signed area of a vertex array.
static Geom_Number	signed_area (const Polygon &poly)
	Compute the actual signed area of a polygon.
static Geom_Number	area (const Array< Point > &verts)
	Compute the absolute area of a vertex array.
static Geom_Number	area (const Polygon &poly)
	Compute the absolute area of a polygon.
static bool	is_convex (const Array< Point > &verts)
	Check if a vertex array forms a convex polygon.
static void	ensure_ccw (Array< Point > &verts)

Detailed Description

Shared polygon helpers used across multiple geometry algorithms.

Provides utilities for working with polygons represented as Array<Point>. Many internal algorithms extract vertices into arrays for efficient indexed access. These helpers centralize common operations.

Note

For direct operations on Polygon objects, prefer the convenience methods Polygon::area(), Polygon::is_convex(), etc. Use this class when working with extracted vertex arrays.

signed_double_area() returns twice the signed area (avoids division). Use area() for the actual area value.

Definition at line 231 of file geom_algorithms.H.

Member Function Documentation

area() [1/2]

static Geom_Number Aleph::GeomPolygonUtils::area ( const Array< Point > &  verts )

inlinestatic

Compute the absolute area of a vertex array.

Definition at line 280 of file geom_algorithms.H.

References Aleph::divide_and_conquer_partition_dp(), and signed_area().

area() [2/2]

static Geom_Number Aleph::GeomPolygonUtils::area ( const Polygon &  poly )

inlinestatic

Compute the absolute area of a polygon.

Definition at line 287 of file geom_algorithms.H.

References signed_area().

ensure_ccw()

static void Aleph::GeomPolygonUtils::ensure_ccw ( Array< Point > &  verts )

inlinestatic

Definition at line 317 of file geom_algorithms.H.

References Aleph::divide_and_conquer_partition_dp(), and signed_double_area().

Referenced by Aleph::MonotonePolygonTriangulation::ensure_ccw(), Aleph::ConvexPolygonOffset::ensure_ccw(), Aleph::BooleanPolygonOperations::ensure_ccw(), Aleph::MinkowskiSumConvex::normalize(), and Aleph::PolygonOffset::operator()().

extract_vertices()

static Array< Point > Aleph::GeomPolygonUtils::extract_vertices ( const Polygon &  poly )

inlinestatic

Extract vertices from a polygon into an array for indexed access.

Definition at line 235 of file geom_algorithms.H.

References Aleph::divide_and_conquer_partition_dp(), Aleph::Dlink::Iterator::has_curr(), Aleph::Array< T >::reserve(), and Aleph::Polygon::size().

Referenced by brute_convex_distance_squared(), Aleph::BooleanPolygonOperations::extract(), Aleph::CuttingEarsTriangulation::extract_vertices(), Aleph::VoronoiDiagramFromDelaunay::extract_vertices(), Aleph::MonotonePolygonTriangulation::extract_vertices(), Aleph::ConvexPolygonDecomposition::extract_vertices(), Aleph::RotatingCalipersConvexPolygon::extract_vertices(), Aleph::ConvexPolygonIntersectionBasic::extract_vertices(), Aleph::MinkowskiSumConvex::extract_vertices(), Aleph::ConvexPolygonOffset::extract_verts(), main(), Aleph::ConvexPolygonDistanceGJK::operator()(), Aleph::PolygonOffset::operator()(), poly_verts(), signed_double_area(), Aleph::VisvalingamWhyattSimplification::simplify_polygon(), Aleph::DouglasPeuckerSimplification::simplify_polygon(), Aleph::ChaikinSmoothing::smooth_polygon(), and TEST_F().

is_convex()

static bool Aleph::GeomPolygonUtils::is_convex ( const Array< Point > &  verts )

inlinestatic

Check if a vertex array forms a convex polygon.

Definition at line 294 of file geom_algorithms.H.

References Aleph::area_of_parallelogram(), and Aleph::divide_and_conquer_partition_dp().

Referenced by Aleph::ConvexPolygonOffset::is_convex(), Aleph::RotatingCalipersConvexPolygon::is_convex(), Aleph::ConvexPolygonIntersectionBasic::is_convex(), Aleph::VoronoiDiagramFromDelaunay::is_convex(), Aleph::MinkowskiSumConvex::is_convex(), and Aleph::ConvexPolygonDistanceGJK::operator()().

signed_area() [1/2]

static Geom_Number Aleph::GeomPolygonUtils::signed_area ( const Array< Point > &  verts )

inlinestatic

Compute the actual signed area of a vertex array.

Definition at line 268 of file geom_algorithms.H.

References Aleph::divide_and_conquer_partition_dp(), and signed_double_area().

Referenced by area(), and area().

signed_area() [2/2]

static Geom_Number Aleph::GeomPolygonUtils::signed_area ( const Polygon &  poly )

inlinestatic

Compute the actual signed area of a polygon.

Definition at line 274 of file geom_algorithms.H.

References signed_double_area().

signed_double_area() [1/2]

static Geom_Number Aleph::GeomPolygonUtils::signed_double_area ( const Array< Point > &  verts )

inlinestatic

Compute twice the signed area (shoelace formula without division).

Returns positive for CCW vertices, negative for CW. This is 2× the actual signed area; use area() or signed_area() for the true value.

Definition at line 249 of file geom_algorithms.H.

References Aleph::divide_and_conquer_partition_dp(), Aleph::Point::get_x(), Aleph::Point::get_y(), and Aleph::sum().

Referenced by Aleph::PolygonOffset::abs_area(), Aleph::PolygonOffset::cleanup(), ensure_ccw(), Aleph::PolygonOffset::extract_contours(), poly_area(), signed_area(), signed_area(), Aleph::MonotonePolygonTriangulation::signed_double_area(), Aleph::MinkowskiSumConvex::signed_double_area(), Aleph::ConvexPolygonOffset::signed_double_area(), Aleph::ConvexPolygonIntersectionBasic::signed_double_area(), Aleph::HalfPlaneIntersection::signed_double_area(), Aleph::CuttingEarsTriangulation::signed_double_area(), and signed_double_area().

signed_double_area() [2/2]

static Geom_Number Aleph::GeomPolygonUtils::signed_double_area ( const Polygon &  poly )

inlinestatic

Compute twice the signed area of a polygon.

Definition at line 262 of file geom_algorithms.H.

References extract_vertices(), and signed_double_area().

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

• geom_algorithms.H