Fill a polygonal face with interior scan lines. More...

#include <vgl_fwd.h>

Inheritance diagram for vgl_polygon_scan_iterator< T >:

Classes
struct	crossedge
	Describes an edge crossing the current scan line. More...

struct	vertind
	Vertex index - uniquely identifies a vertex in the array chains. More...

Public Types
typedef vgl_polygon< T >::point_t	Point2

Public Member Functions
	vgl_polygon_scan_iterator (vgl_polygon< T > const &face, bool boundaryp=true)
	Construct with a polygon and bool indicating whether boundary included. More...

	vgl_polygon_scan_iterator (vgl_polygon< T > const &face, bool boundaryp, vgl_box_2d< T > const &window)
	Construct with a polygon, bool indicating whether boundary included and window (area visible). More...

	~vgl_polygon_scan_iterator () override
	Destructor. More...

void	reset () override
	Resets iterator to first segment of first scan line. More...

bool	next () override
	Moves iterator to next segment. More...

int	scany () const override
	Returns current scan line. More...

int	startx () const override
	Returns start of current span. More...

int	endx () const override
	Returns end of current span. More...

T	fstartx () const
	Returns start of current span (floating point value). More...

T	fendx () const
	Returns end of current span (floating point value). More...

T	fscany () const
	Returns current scan line (floating point value). More...

void	get_crossedge_vertices (int &chainnum, int &vertnum, int &numcrossedges)

int	count ()
	Number of image points (= integer grid points) inside the region. More...

Private Member Functions
	vgl_polygon_scan_iterator (const vgl_polygon_scan_iterator &)=delete

vgl_polygon_scan_iterator &	operator= (const vgl_polygon_scan_iterator &)=delete

T	get_x (vertind v) const

T	get_y (vertind v) const

Point2	get_pt (vertind v) const

void	init ()

void	delete_edge (vertind v)

void	insert_edge (vertind v)

void	get_next_vert (vertind v, vertind &next)
	Returns the vertex following v in v's chain. More...

void	get_prev_vert (vertind v, vertind &prev)
	Returns the vertex preceding v in v's chain. More...

void	display_chains ()

void	display_crossedges ()

Private Attributes
int	boundp
	boolean indicating if boundary should be included or not More...

int	xl
	left bound of current span More...

T	fxl
	left bound of current span (floating point value) More...

int	xr
	right bound of current span More...

T	fxr
	right bound of current span (floating point value) More...

int	k
	current index of vertices ordered by increasing y More...

int	y0
	bottommost scan line More...

int	y1
	topmost scan line More...

int	y
	current scan line More...

T	fy
	floating point value of current scan line (i.e. T(y)) More...

int	curcrossedge
	crossedge marking start of next scan segment More...

vgl_box_2d< T >	win
	clipping window More...

bool	have_window

vgl_polygon< T >	poly_
	the polygon More...

vertind *	yverts
	array of all vertices ordered by y coordinate More...

crossedge *	crossedges
	array of edges crossing current scan line More...

int	numcrossedges
	number of edges currently crossing scan line More...

int	numverts
	total number of vertices comprising face More...

Detailed Description

template<class T>
class vgl_polygon_scan_iterator< T >

Fill a polygonal face with interior scan lines.

This class provides an iterator-style interface to polygon scan conversion. There are convenient constructors from vgl_polygon, and_ lists of floats. An auxiliary clipping window can be specified by the constructor argument, vgl_box_2d<T> win.

Concave Polygon Scan Conversion by Paul Heckbert from "Graphics Gems", Academic Press, 1990

Scan convert nvert-sided concave non-simple polygon with vertices at (point[i].x, point[i].y) for i in [0..nvert-1] within the window win by calling spanproc for each visible span of pixels. Polygon can be clockwise or counterclockwise. Algorithm does uniform point sampling at pixel centers. Inside-outside test done by Jordan's rule: a point is considered inside if an emanating ray intersects the polygon an odd number of times.

Note: The span limits, startx and endx, are closed intervals. That is, you can use the endpoints of the span as valid interior points. Also, the initial and final y scan lines returned by the iterator are interior to the polygon. The constructor argument, win, is a clipping window that is intersected with the polygonal region to determine the actual scanned area.

Example usage:

vgl_polygon_scan_iterator<float> psi(mypoints);
psi.set_include_boundary(true); // optional flag, default is true
for (psi.reset(); psi.next(); ) {
  int y = psi.scany();
  for (int x = psi.startx(); x <= psi.endx(); ++x)
       ....
}

Definition at line 33 of file vgl_fwd.h.

Member Typedef Documentation

◆ Point2

template<class T>

typedef vgl_polygon<T>::point_t vgl_polygon_scan_iterator< T >::Point2

Definition at line 77 of file vgl_polygon_scan_iterator.h.

Constructor & Destructor Documentation

◆ vgl_polygon_scan_iterator() [1/3]

template<class T >

vgl_polygon_scan_iterator< T >::vgl_polygon_scan_iterator	(	vgl_polygon< T > const &	face,
		bool	boundaryp = `true`
	)

Construct with a polygon and bool indicating whether boundary included.

Definition at line 96 of file vgl_polygon_scan_iterator.hxx.

◆ vgl_polygon_scan_iterator() [2/3]

template<class T >

vgl_polygon_scan_iterator< T >::vgl_polygon_scan_iterator	(	vgl_polygon< T > const &	face,
		bool	boundaryp,
		vgl_box_2d< T > const &	window
	)

Construct with a polygon, bool indicating whether boundary included and window (area visible).

Definition at line 109 of file vgl_polygon_scan_iterator.hxx.

◆ ~vgl_polygon_scan_iterator()

template<class T >

vgl_polygon_scan_iterator< T >::~vgl_polygon_scan_iterator ( )

override

Destructor.

Definition at line 86 of file vgl_polygon_scan_iterator.hxx.

◆ vgl_polygon_scan_iterator() [3/3]

template<class T>

vgl_polygon_scan_iterator< T >::vgl_polygon_scan_iterator ( const vgl_polygon_scan_iterator< T > & )

privatedelete

Member Function Documentation

◆ count()

int vgl_region_scan_iterator::count ( )

inlineinherited

Number of image points (= integer grid points) inside the region.

Definition at line 48 of file vgl_region_scan_iterator.h.

◆ delete_edge()

template<class T >

void vgl_polygon_scan_iterator< T >::delete_edge ( vertind v )

private

Definition at line 196 of file vgl_polygon_scan_iterator.hxx.

◆ display_chains()

template<class T >

void vgl_polygon_scan_iterator< T >::display_chains ( )

private

Definition at line 423 of file vgl_polygon_scan_iterator.hxx.

◆ display_crossedges()

template<class T >

void vgl_polygon_scan_iterator< T >::display_crossedges ( )

private

Definition at line 444 of file vgl_polygon_scan_iterator.hxx.

◆ endx()

template<class T>

int vgl_polygon_scan_iterator< T >::endx ( ) const

inlineoverridevirtual

Returns end of current span.

Implements vgl_region_scan_iterator.

Definition at line 106 of file vgl_polygon_scan_iterator.h.

◆ fendx()

template<class T>

T vgl_polygon_scan_iterator< T >::fendx ( ) const

inline

Returns end of current span (floating point value).

Definition at line 112 of file vgl_polygon_scan_iterator.h.

◆ fscany()

template<class T>

T vgl_polygon_scan_iterator< T >::fscany ( ) const

inline

Returns current scan line (floating point value).

Definition at line 115 of file vgl_polygon_scan_iterator.h.

◆ fstartx()

template<class T>

T vgl_polygon_scan_iterator< T >::fstartx ( ) const

inline

Returns start of current span (floating point value).

Definition at line 109 of file vgl_polygon_scan_iterator.h.

◆ get_crossedge_vertices()

template<class T >

void vgl_polygon_scan_iterator< T >::get_crossedge_vertices	(	int *&	chainnum,
		int *&	vertnum,
		int &	numcrossedges
	)

Definition at line 268 of file vgl_polygon_scan_iterator.hxx.

◆ get_next_vert()

template<class T >

void vgl_polygon_scan_iterator< T >::get_next_vert	(	vertind	v,
		vertind &	nextvert
	)

private

Returns the vertex following v in v's chain.

The vertex is returned through the parameter nextvert. I get a syntax error when I tried to return an object of type vertind. Compiler error says the default return type is int???

Definition at line 398 of file vgl_polygon_scan_iterator.hxx.

◆ get_prev_vert()

template<class T >

void vgl_polygon_scan_iterator< T >::get_prev_vert	(	vertind	v,
		vertind &	prevvert
	)

private

Returns the vertex preceding v in v's chain.

The vertex is returned through the parameter prevvert. I get a syntax error when I tried to return an object of type vertind. Compiler error says the default return type is int???

Definition at line 411 of file vgl_polygon_scan_iterator.hxx.

◆ get_pt()

template<class T>

Point2 vgl_polygon_scan_iterator< T >::get_pt ( vertind v ) const

inlineprivate

Definition at line 151 of file vgl_polygon_scan_iterator.h.

◆ get_x()

template<class T>

T vgl_polygon_scan_iterator< T >::get_x ( vertind v ) const

inlineprivate

Definition at line 145 of file vgl_polygon_scan_iterator.h.

◆ get_y()

template<class T>

T vgl_polygon_scan_iterator< T >::get_y ( vertind v ) const

inlineprivate

Definition at line 148 of file vgl_polygon_scan_iterator.h.

◆ init()

template<class T >

void vgl_polygon_scan_iterator< T >::init ( )

private

Definition at line 124 of file vgl_polygon_scan_iterator.hxx.

◆ insert_edge()

template<class T >

void vgl_polygon_scan_iterator< T >::insert_edge ( vertind v )

private

Definition at line 216 of file vgl_polygon_scan_iterator.hxx.

◆ next()

template<class T >

bool vgl_polygon_scan_iterator< T >::next ( )

overridevirtual

Moves iterator to next segment.

Implements vgl_region_scan_iterator.

Definition at line 289 of file vgl_polygon_scan_iterator.hxx.

◆ operator=()

template<class T>

vgl_polygon_scan_iterator& vgl_polygon_scan_iterator< T >::operator= ( const vgl_polygon_scan_iterator< T > & )

privatedelete

◆ reset()

template<class T >

void vgl_polygon_scan_iterator< T >::reset ( )

overridevirtual

Resets iterator to first segment of first scan line.

Implements vgl_region_scan_iterator.

Definition at line 246 of file vgl_polygon_scan_iterator.hxx.

◆ scany()

template<class T>

int vgl_polygon_scan_iterator< T >::scany ( ) const

inlineoverridevirtual

Returns current scan line.

Implements vgl_region_scan_iterator.

Definition at line 100 of file vgl_polygon_scan_iterator.h.

◆ startx()

template<class T>

int vgl_polygon_scan_iterator< T >::startx ( ) const

inlineoverridevirtual

Returns start of current span.

Implements vgl_region_scan_iterator.

Definition at line 103 of file vgl_polygon_scan_iterator.h.

Member Data Documentation

◆ boundp

template<class T>

int vgl_polygon_scan_iterator< T >::boundp

private

boolean indicating if boundary should be included or not

Definition at line 59 of file vgl_polygon_scan_iterator.h.

◆ crossedges

template<class T>

crossedge* vgl_polygon_scan_iterator< T >::crossedges

private

array of edges crossing current scan line

Definition at line 140 of file vgl_polygon_scan_iterator.h.

◆ curcrossedge

template<class T>

int vgl_polygon_scan_iterator< T >::curcrossedge

private

crossedge marking start of next scan segment

Definition at line 69 of file vgl_polygon_scan_iterator.h.

◆ fxl

template<class T>

T vgl_polygon_scan_iterator< T >::fxl

private

left bound of current span (floating point value)

Definition at line 61 of file vgl_polygon_scan_iterator.h.

◆ fxr

template<class T>

T vgl_polygon_scan_iterator< T >::fxr

private

right bound of current span (floating point value)

Definition at line 63 of file vgl_polygon_scan_iterator.h.

◆ fy

template<class T>

T vgl_polygon_scan_iterator< T >::fy

private

floating point value of current scan line (i.e. T(y))

Definition at line 68 of file vgl_polygon_scan_iterator.h.

◆ have_window

template<class T>

bool vgl_polygon_scan_iterator< T >::have_window

private

Definition at line 71 of file vgl_polygon_scan_iterator.h.

◆ k

template<class T>

int vgl_polygon_scan_iterator< T >::k

private

current index of vertices ordered by increasing y

Definition at line 64 of file vgl_polygon_scan_iterator.h.

◆ numcrossedges

template<class T>

int vgl_polygon_scan_iterator< T >::numcrossedges

private

number of edges currently crossing scan line

Definition at line 141 of file vgl_polygon_scan_iterator.h.

◆ numverts

template<class T>

int vgl_polygon_scan_iterator< T >::numverts

private

total number of vertices comprising face

Definition at line 142 of file vgl_polygon_scan_iterator.h.

◆ poly_

template<class T>

vgl_polygon<T> vgl_polygon_scan_iterator< T >::poly_

private

the polygon

Definition at line 73 of file vgl_polygon_scan_iterator.h.

◆ win

template<class T>

vgl_box_2d<T> vgl_polygon_scan_iterator< T >::win

private

clipping window

Definition at line 70 of file vgl_polygon_scan_iterator.h.

◆ xl

template<class T>

int vgl_polygon_scan_iterator< T >::xl

private

left bound of current span

Definition at line 60 of file vgl_polygon_scan_iterator.h.

◆ xr

template<class T>

int vgl_polygon_scan_iterator< T >::xr

private

right bound of current span

Definition at line 62 of file vgl_polygon_scan_iterator.h.

◆ y

template<class T>

int vgl_polygon_scan_iterator< T >::y

private

current scan line

Definition at line 67 of file vgl_polygon_scan_iterator.h.

◆ y0

template<class T>

int vgl_polygon_scan_iterator< T >::y0

private

bottommost scan line

Definition at line 65 of file vgl_polygon_scan_iterator.h.

◆ y1

template<class T>

int vgl_polygon_scan_iterator< T >::y1

private

topmost scan line

Definition at line 66 of file vgl_polygon_scan_iterator.h.

◆ yverts

template<class T>

vertind* vgl_polygon_scan_iterator< T >::yverts

private

array of all vertices ordered by y coordinate

Definition at line 139 of file vgl_polygon_scan_iterator.h.

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

Classes

Public Types

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

template<class T> class vgl_polygon_scan_iterator< T >

Member Typedef Documentation

◆ Point2

Constructor & Destructor Documentation

◆ vgl_polygon_scan_iterator() [1/3]

◆ vgl_polygon_scan_iterator() [2/3]

◆ ~vgl_polygon_scan_iterator()

◆ vgl_polygon_scan_iterator() [3/3]

Member Function Documentation

◆ count()

◆ delete_edge()

◆ display_chains()

◆ display_crossedges()

◆ endx()

◆ fendx()

◆ fscany()

◆ fstartx()

◆ get_crossedge_vertices()

◆ get_next_vert()

◆ get_prev_vert()

◆ get_pt()

◆ get_x()

◆ get_y()

◆ init()

◆ insert_edge()

◆ next()

◆ operator=()

◆ reset()

◆ scany()

◆ startx()

Member Data Documentation

◆ boundp

◆ crossedges

◆ curcrossedge

◆ fxl

◆ fxr

◆ fy

◆ have_window

◆ k

◆ numcrossedges

◆ numverts

◆ poly_

◆ win

◆ xl

◆ xr

◆ y

◆ y0

◆ y1

◆ yverts

template<class T>
class vgl_polygon_scan_iterator< T >