CWinPolygon Class Reference

Encapsulates a polygon. More...

#include <WinPolygon.h>

Collaboration diagram for CWinPolygon:


Public Types
typedef CWinPolygon::tagRANGE	RANGE
	2D range
typedef CWinPolygon::tagRANGE *	LPRANGE
	2D range
Public Member Functions
long	Distance (CWinPolygon *pWp)
	Calculates the minimum distance between polygon points.
BOOL	GetIBeam (LPPOINT ptTop, LPPOINT ptBottom, BOOL bInvY=FALSE)
	Returns points representing the vertical height of the polygon.
BOOL	Scale (LPRECT pSrc, LPRECT pDst)
	Scales the polygon points according to the ratio of specified rectangles.
BOOL	Intersect (LPPOINT pPts, DWORD dwPts)
	Collision tests with another polygon.
BOOL	Intersect (CWinPolygon *pWp)
	Collision tests with another polygon.
void	rScanSort (LPPOINT pPts, DWORD left, DWORD right)
	Performs a recursive quick sort on the polygons.
BOOL	ScanSort ()
	Performs a recursive quick sort on the polygons.
BOOL	Inflate (long x, long y)
	Inflates the polygon by the specified amount.
float	SimpleArea ()
	Calculates a rough estimate of the polygon area.
BOOL	ConvexHull ()
	Calculates a convex hull of the polygon.
BOOL	ApxConvexHull ()
	Calculates an approximate convex hull.
BOOL	FromMap (LPDWORD map, long x, long y, long w, long h, UINT th, LPBYTE buf=NULL)
	Creates a polygon from a map.
	CWinPolygon ()
	Default constructor.
	CWinPolygon (LPPOINT pPts, DWORD dwPts)
	Constructs a polygon object from a list of points.
	CWinPolygon (CWinPolygon &wp)
	Constructs a polygon object by copying another CWinPolygon object.
virtual	~CWinPolygon ()
	Destructor.
void	Destroy ()
	Releases the polygon resources.
BOOL	Allocate (DWORD sz)
	Allocates the specified number of points in the polygon.
LPPOINT	GetPoints ()
	Returns a pointer to the polygon POINT structure array.
DWORD	GetNumPoints ()
	Returns the total number of points in the polygon.
DWORD	GetNumEdges ()
	Returns the number of edges the polygon has.
LPLINE	GetEdge (DWORD i)
	Returns a line struture pointer for the specified edge.
BOOL	PtInPolygon (LPPOINT ppt)
	Tests to see if the point lies within the polygon.
BOOL	CombinePoint (LPPOINT ppt)
	Adds a point into the current polygon by calculating the closest edge.
CWinPolygon &	operator+= (LPPOINT ppt)
	Appends point to the end of the polygon.
BOOL	AddPoint (LPPOINT ppt)
	Appends point to the end of the polygon.
BOOL	AddPoints (LPPOINT ppt, DWORD dwPts)
	Appends points to the end of the polygon point list.
BOOL	AddPoint (long x, long y)
	Appends point to the end of the polygon.
BOOL	AddPolygon (CWinPolygon *pWp)
	Add The points from the specified polygon.
BOOL	RemovePoint (DWORD dwPt)
	Removes the specified point from the polygon.
BOOL	RemovePoint (long x, long y)
	Removes the specified point from the polygon.
	operator DWORD ()
	Returns the number of points in the polygon.
	operator LPPOINT ()
	Returns a pointer to the polygon POINT structure array.
POINT &	operator[] (DWORD i)
	Returns a reference to the specified point.
long	isLeft (POINT P0, POINT P1, POINT P2)
	Returns greater than zero if the specified triangle is left-handed.
long	ComparePoint (POINT p1, POINT p2)
	For sorting points.
POINT	CalculateCenter ()
	Calculates the center point of the polygon.
CWinPolygon &	operator= (CWinPolygon &wp)
	Copies another CWinPolygon object.
BOOL	SetPoints (LPPOINT pPts, DWORD dwPts)
	Sets the value of the polygon points.
BOOL	SetPoints (CWinPolygon *pWp)
	Sets the value of the polygon points.
void	Offset (LPPOINT ppt)
	Offsets the polygon by the specified distance.
void	Offset (long x, long y)
	Offsets the polygon by the specified distance.
float	ConvexArea ()
	Calculates the area of a convex polygon.
Static Public Member Functions
static BOOL	PtInPolygon (LPPOINT pptList, DWORD dwListSize, LPPOINT ppt)
	Tests to see if the point lies within the polygon.
static BOOL	CombinePoint (LPPOINT pptList, DWORD dwListSize, LPPOINT ppt)
	Adds a point into the current polygon by calculating the closest edge.
static float	TriangleArea (float a, float b, float c)
	Calculates the area of a triangle given the lengths of it's sides.
static float	TriangleArea (float x1, float y1, float x2, float y2, float x3, float y3)
	Calculates the area of the triangle defined by three points.
Classes
struct	tagRANGE
	2D range More...

Detailed Description

Encapsulates a polygon.

This structure encapsulates a polylgon and provides a few nifty functions for manipulating them. The polygon is stored simply as a list of points.

Constructor & Destructor Documentation

CWinPolygon::CWinPolygon ( LPPOINT pPts,

DWORD dwPts

) [inline]

Constructs a polygon object from a list of points.

Parameters:

[in] pPts - Pointer to POINT structure array

[in] dwPts - Number of points in pPts

CWinPolygon::CWinPolygon ( CWinPolygon & wp ) [inline]

Constructs a polygon object by copying another CWinPolygon object.

Parameters:

[in] wp - Pointer to CWinPolygon object

Member Function Documentation

BOOL CWinPolygon::AddPoint ( long x,

long y

) [inline]

Appends point to the end of the polygon.

Parameters:

[in] x - Horizontal offset of point

[in] y - Vertical offset of point

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::AddPoint ( LPPOINT ppt ) [inline]

Appends point to the end of the polygon.

Parameters:

[in] ppt - Point to add

Returns:
Non-zero if added

See also:

BOOL CWinPolygon::AddPoints ( LPPOINT ppt,

DWORD dwPts

) [inline]

Appends points to the end of the polygon point list.

Parameters:

[in] ppt - List of points

[in] dwPts - Number of points in ppt

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::AddPolygon ( CWinPolygon * pWp ) [inline]

Add The points from the specified polygon.

Parameters:

[in] pWp - Polygon containing points to add

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::Allocate ( DWORD sz ) [inline]

Allocates the specified number of points in the polygon.

Parameters:

[in] sz - Number of points to allocate

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::ApxConvexHull ( )

Calculates an approximate convex hull.
After this call, this class will contain the approximate convex hull of the original points.
Similar to the BFP Approximate Hull Algorithm ( Bentley-Faust-Preparata, 1982 ) but slightly faster

Warning:
This does not calculate an exact convex hull. For a precise convex hull, call ConvexHull()

Returns:
Non-zero if success

See also:

POINT CWinPolygon::CalculateCenter ( )

Calculates the center point of the polygon.

Returns:
Center point of polygon

See also:

BOOL CWinPolygon::CombinePoint ( LPPOINT pptList,

DWORD dwListSize,

LPPOINT ppt

) [static]

Adds a point into the current polygon by calculating the closest edge.

Parameters:

[in] pptList - Pointer to POINT structure array

[in] dwListSize - Number of points in pptList

[in] ppt - Point to add

Magic function

Warning:
I haven't implemented this function yet!
The idea is just to calculate the closest edge to the polygon and conjoin the point into the polygon at that edge.

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::CombinePoint ( LPPOINT ppt ) [inline]

Adds a point into the current polygon by calculating the closest edge.

Parameters:

[in] ppt - Point to add

Magic function

Warning:
I haven't implemented this function yet!
The idea is just to calculate the closest edge to the polygon and conjoin the point into the polygon at that edge.

Returns:
Non-zero if success

See also:

long CWinPolygon::ComparePoint ( POINT p1,

POINT p2

) [inline]

For sorting points.

Parameters:

[in] p1 - First point

[in] p2 - Second point

-1 if p1 is before p2 0 if points are the same 1 if p2 is before p1

Returns:

See also:

float CWinPolygon::ConvexArea ( )

Calculates the area of a convex polygon.
The polygon in the object must be convex or this function returns an undefined value!

Returns:
Area

See also:

BOOL CWinPolygon::ConvexHull ( )

Calculates a convex hull of the polygon.
After calling this function, the polygon will contain a convex hull of the original polygon. This calculates an exact convex hull.

Warning:
Requires sorting, call ScanSort() before this function unless you know the points are sorted.
Copyright notice for this function:
Based on "Andrew's Monotone Chain algorithm" Copyright 2001, softSurfer (www.softsurfer.com) This code may be freely used and modified for any purpose providing that this copyright notice is included with it. SoftSurfer makes no warranty for this code, and cannot be held liable for any real or imagined damage resulting from its use. Users of this code must verify correctness for their application.

Returns:
Non-zero if success

See also:

long CWinPolygon::Distance ( CWinPolygon * pWp )

Calculates the minimum distance between polygon points.

Parameters:

[in] pWp - CWinPolygon object

This function calculates the minimum distance between to points in the polygons.

Warning:
This function currently makes only a rough estimation of distance.

Returns:
The distance between the closest points.

See also:

BOOL CWinPolygon::FromMap ( LPDWORD map,

long x,

long y,

long w,

long h,

UINT th,

LPBYTE buf = NULL

)

Creates a polygon from a map.

Parameters:

[in] map - pointer to map values

[in] x - Horizontal offset for the extraction

[in] y - Vertical offset for the extraction

[in] w - Width of the image area for the extraction

[in] h - Height of the image area for the extraction

[in] th - Value threshold

[in] buf - Pointer to buffer that holds map walk data. You can speed up multiple calls to this function by allocating this ahead of time, then passing it into this function.

This function can create a polygon by 'filling' around a bitmap image. Great for selcting parts of an image.

Returns:
Non-zero if success

See also:

LPLINE CWinPolygon::GetEdge ( DWORD i ) [inline]

Returns a line struture pointer for the specified edge.

Parameters:

[in] i - Edge index

This function returns an offset into the point array of the specified edge. It does not allocate any new memory

Returns:
Pointer to the specified edge

See also:

BOOL CWinPolygon::GetIBeam ( LPPOINT ptTop,

LPPOINT ptBottom,

BOOL bInvY = FALSE

)

Returns points representing the vertical height of the polygon.

Parameters:

[out] ptTop - The top point of the line

[out] ptBottom - Bottom point of the line

[in] bInvY - Non-zero to flip the line upside down.

This function basically creates a line that cuts the polygon in half vertcally. The line is as long as the polygon is high, and is located roughly at the horizontal center.
I know this is a strange function, but I needed it OK?

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::Inflate ( long x,

long y

)

Inflates the polygon by the specified amount.

Parameters:

[in] x - Horizontal inflate value

[in] y - Vertical inflate value

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::Intersect ( CWinPolygon * pWp ) [inline]

Collision tests with another polygon.

Parameters:

[in] pWp - CWinPolygon object to collision test

Returns:
Non-zero if polygons intersect

See also:

BOOL CWinPolygon::Intersect ( LPPOINT pPts,

DWORD dwPts

)

Collision tests with another polygon.

Parameters:

[in] pPts - Points in polygon for collision test

[in] dwPts - Number of points in pPts

Unfortunately, this is not a very optimized function. But it works well.

Returns:
Non-zero if polygons intersect

See also:

long CWinPolygon::isLeft ( POINT P0,

POINT P1,

POINT P2

) [inline]

Returns greater than zero if the specified triangle is left-handed.

Parameters:

[in] P0 - First point in triangle

[in] P1 - Second point in triangle

[in] P2 - Third point in triangle

Returns:
greater than zero if left handed triangle is specified

See also:

void CWinPolygon::Offset ( long x,

long y

) [inline]

Offsets the polygon by the specified distance.

Parameters:

[in] x - Horizontal offset distance

[in] y - Vertical offset distance

void CWinPolygon::Offset ( LPPOINT ppt ) [inline]

Offsets the polygon by the specified distance.

Parameters:

[in] ppt - Point specifying offset distance

CWinPolygon& CWinPolygon::operator+= ( LPPOINT ppt ) [inline]

Appends point to the end of the polygon.

Parameters:

[in] ppt - Point to add

Returns:
Reference to this object

See also:

BOOL CWinPolygon::PtInPolygon ( LPPOINT pptList,

DWORD dwListSize,

LPPOINT ppt

) [static]

Tests to see if the point lies within the polygon.

Parameters:

[in] pptList - Polygon point list

[in] dwListSize - Number of points in pptList

[in] ppt - Point to test

This function works well and is reasonably fast.

Returns:
Non-zero if point is within the polygon

See also:

BOOL CWinPolygon::PtInPolygon ( LPPOINT ppt ) [inline]

Tests to see if the point lies within the polygon.

Parameters:

[in] ppt - Point to test

This function works well and is reasonably fast.

Returns:
Non-zero if point is within the polygon

See also:

BOOL CWinPolygon::RemovePoint ( long x,

long y

) [inline]

Removes the specified point from the polygon.

Parameters:

[in] x - Horizontal offset of point

[in] y - Vertical offset of point

Searches the polygon for a point matching the specified x, y position and removes the first occurence.

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::RemovePoint ( DWORD dwPt ) [inline]

Removes the specified point from the polygon.

Parameters:

[in] dwPt - Index of point to remove

Returns:
Non-zero if success

See also:

void CWinPolygon::rScanSort ( LPPOINT pPts,

DWORD left,

DWORD right

)

Performs a recursive quick sort on the polygons.

Parameters:

[in] pPts - Points to sort

[in] left - Left index

[in] right - Right index

Call ScanSort(). Don't call this function directly

BOOL CWinPolygon::Scale ( LPRECT pSrc,

LPRECT pDst

)

Scales the polygon points according to the ratio of specified rectangles.

Parameters:

[in] pSrc - Source rect

[in] pDst - Destination rect

Calculates the vertical and horizontal difference and scales the polygon accordingly. Great for scaling a polygon for overlaying on one image to the same image of a different size.

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::ScanSort ( )

Performs a recursive quick sort on the polygons.
Reasonably fast sorting algorithm.

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::SetPoints ( CWinPolygon * pWp ) [inline]

Sets the value of the polygon points.

Parameters:

[in] pWp - Polygon containing point values

Returns:
Non-zero if success

See also:

BOOL CWinPolygon::SetPoints ( LPPOINT pPts,

DWORD dwPts

) [inline]

Sets the value of the polygon points.

Parameters:

[in] pPts - Pointer to POINT array

[in] dwPts - Number of points in pPts

Returns:
Non-zero if success

See also:

float CWinPolygon::SimpleArea ( )

Calculates a rough estimate of the polygon area.

Returns:
value representing the rough polygon area.

See also:

static float CWinPolygon::TriangleArea ( float x1,

float y1,

float x2,

float y2,

float x3,

float y3

) [inline, static]

Calculates the area of the triangle defined by three points.

Parameters:

[in] x1 - Horizontal offset first point

[in] y1 - Vertical offset first point

[in] x2 - Horizontal offset second point

[in] y2 - Vertical offset second point

[in] x3 - Horizontal offset third point

[in] y3 - Vertical offset third point

Returns:
Area of the specified triangle

See also:

static float CWinPolygon::TriangleArea ( float a,

float b,

float c

) [inline, static]

Calculates the area of a triangle given the lengths of it's sides.

Parameters:

[in] a - First side length

[in] b - Second side length

[in] c - Third side length

Returns:
Area of the triangle

See also:

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

inc/WinPolygon.h
WinPolygon.cpp

CWinPolygon Class Reference

Public Types

Public Member Functions

Static Public Member Functions

Classes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation