#include <vpPolygon.h>

Public Member Functions
	vpPolygon ()

	vpPolygon (const std::vector< vpImagePoint > &corners)

	vpPolygon (const vpPolygon &poly)

virtual	~vpPolygon ()

vpPolygon &	operator= (const vpPolygon &poly)

void	buildFrom (const std::vector< vpImagePoint > &corners)

void	buildFrom (const std::vector< vpPoint > &corners, const vpCameraParameters &cam)

void	initClick (const vpImage< unsigned char > &I)

bool	isInside (const vpImagePoint &iP)

void	display (const vpImage< unsigned char > &I, const vpColor &color, unsigned int thickness=1)

const std::vector< vpImagePoint > &	getCorners () const

double	getArea () const

vpImagePoint	getCenter () const

vpRect	getBoundingBox () const

Protected Member Functions
void	init (const std::vector< vpImagePoint > &corners)

void	updateArea ()

void	updateCenter ()

void	updateBoundingBox ()

Protected Attributes
std::vector< vpImagePoint >	_corners

vpImagePoint	_center

double	_area

bool	_goodPoly

vpRect	_bbox

Detailed Description

Defines a generic 2D polygon.

A polygon is internally represented by N 2D points.

By default three coordinates in the $ (i,j) $ frame (see vpImagePoint class documentation for more details about the frame) are used $ (0,0) $ , $ (1,0) $ and $ (0,1) $ .

The code bellow shows how to manipulate a polygon.

#include <iostream>
#include <visp/vpPolygon.h>
int main()
{
  std::vector<vpImagePoint> corners;
  // Initialize the corners vector with 4 points 
  corners.push_back( vpImagePoint( 50, 100) );
  corners.push_back( vpImagePoint( 50, 300) );
  corners.push_back( vpImagePoint(200, 300) );
  corners.push_back( vpImagePoint(200, 100) );
  // Initialize a polygon with the corners
  vpPolygon polygon(corners);
  // Get the polygon bounding box
  vpRect bbox = polygon.getBoundingBox();
  std::cout << "Bounding box: " << bbox.getTopLeft() << " to " << bbox.getBottomRight() << std::endl;
  // Get the polygon surface and center
  std::cout << "Area: " << polygon.getArea() << std::endl;
  std::cout << "Center: " << polygon.getCenter() << std::endl;
  // Check if a point is inside the polygon
  vpImagePoint ip(550, 200);
  std::cout << "The point " << ip << " is " << (polygon.isInside(ip) ? "inside":"outside") << " the polygon" << std::endl; 
  return 0;
}

Definition at line 102 of file vpPolygon.h.

Constructor & Destructor Documentation

vpPolygon::vpPolygon ( )

Basic constructor.

By default, it defines a triangle with the three 2D points coordinates : $ (0,0) $ , $ (1,0) $ and $ (0,1) $ .

Definition at line 59 of file vpPolygon.cpp.

References _goodPoly, and init().

vpPolygon::vpPolygon ( const std::vector< vpImagePoint > & corners )

Constructor which initialise the polygon thanks to the given corners.

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The Points defining the corners.

Definition at line 76 of file vpPolygon.cpp.

References _goodPoly, and init().

vpPolygon::vpPolygon ( const vpPolygon & poly )

Copy constructor

Parameters

poly	: The polygon used for the initialisation.

Definition at line 89 of file vpPolygon.cpp.

References _area, _center, _corners, and _goodPoly.

vpPolygon::~vpPolygon ( )

virtual

Basic destructor

Definition at line 100 of file vpPolygon.cpp.

Member Function Documentation

void vpPolygon::buildFrom ( const std::vector< vpImagePoint > & corners )

Initialise the triangle thanks to the collection of 2D points (in pixel).

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The corners of the polyon.

Definition at line 127 of file vpPolygon.cpp.

References init().

Referenced by buildFrom(), and initClick().

void vpPolygon::buildFrom	(	const std::vector< vpPoint > &	corners,
		const vpCameraParameters &	cam
	)

Initialise the triangle thanks to the collection of 2D points (in meter). The fields x and y are used to compute the corresponding coordinates in pixel thanks to the camera parameters cam.

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners	: The corners of the polyon.
cam	: The camera parameters used to convert the coordinates from meter to pixel.

Definition at line 144 of file vpPolygon.cpp.

References buildFrom(), and vpMeterPixelConversion::convertPoint().

void vpPolygon::display	(	const vpImage< unsigned char > &	I,
		const vpColor &	color,
		unsigned int	thickness = `1`
	)

Display the polygon in the image (overlay, so the image is not modified). A call to the flush() method is necessary.

Parameters

I	: The image where is displayed the polygon.
color	: The color of the lines of the polygon.
thickness	: The thickness of the lines used to display the polygon.

Definition at line 403 of file vpPolygon.cpp.

References _corners, and vpDisplay::displayLine().

double vpPolygon::getArea ( ) const

inline

Return the area of the polygon. The area is computed when the polygon is built from the corners.

Returns: The area of the polygon.

Definition at line 148 of file vpPolygon.h.

vpRect vpPolygon::getBoundingBox ( ) const

inline

Return the bounding box. The bounding box is the smallest rectangle containing all the polygon.

Returns: The bounding box of the polygon.

Definition at line 168 of file vpPolygon.h.

vpImagePoint vpPolygon::getCenter ( ) const

inline

Return the center of the polygon. The center is computed when the polygon is built from the corners.

Returns: The area of the polygon.

Definition at line 158 of file vpPolygon.h.

const std::vector<vpImagePoint>& vpPolygon::getCorners ( ) const

inline

Get the corners of the polygon.

Returns: A reference to the corners.

Definition at line 137 of file vpPolygon.h.

void vpPolygon::init ( const std::vector< vpImagePoint > & corners )

protected

Intialise the polygon using the collection of image points. This method compute come internal variables such as center, area, ...

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The corners of the polyon.

Definition at line 189 of file vpPolygon.cpp.

References _corners, updateArea(), updateBoundingBox(), and updateCenter().

Referenced by buildFrom(), and vpPolygon().

void vpPolygon::initClick ( const vpImage< unsigned char > & I )

Initialise the polygon by (left-)clicking to add a corners to the polygon. A right click is used to stop the addition of new corner.

Parameters

I	: The image where to click to initialise the corners.

Definition at line 160 of file vpPolygon.cpp.

References buildFrom(), vpMouseButton::button1, vpDisplay::displayCross(), vpDisplay::flush(), vpDisplay::getClick(), and vpColor::red.

bool vpPolygon::isInside ( const vpImagePoint & ip )

Check if the 2D point $ iP $ is inside the polygon.

Parameters

ip	: The point which have to be tested.

Returns: Returns true if the point is inside the triangle, false otherwise.

Definition at line 247 of file vpPolygon.cpp.

References _corners, vpImagePoint::get_i(), vpImagePoint::get_j(), vpImagePoint::set_i(), and vpImagePoint::set_j().

vpPolygon & vpPolygon::operator= ( const vpPolygon & poly )

Equal operator.

Assign poly to this polygon and return a reference to it.

Definition at line 110 of file vpPolygon.cpp.

References _area, _center, _corners, and _goodPoly.

void vpPolygon::updateArea ( )

protected

Update the _area attribute of the polygon using the corners.

The area is computed using the formula:

$A = \frac{1}{2} \sum_{i=0}^{n-1} (x_1 y_{i+1} - x_{i+1} y_{i})$

Definition at line 291 of file vpPolygon.cpp.

References _area, _corners, and _goodPoly.

Referenced by init().

void vpPolygon::updateBoundingBox ( )

protected

Definition at line 365 of file vpPolygon.cpp.

References _bbox, _corners, _goodPoly, vpRect::setBottomRight(), and vpRect::setTopLeft().

Referenced by init().

void vpPolygon::updateCenter ( )

protected

Update the _center attribute of the polygon using the corners.

The i coordinates is computed using:

$i = \frac{1}{6{area}} \sum_{i=0}^{n-1} (i_i + i_{i+1})(i_{i+1} j_i - j_{i+1} i_i)$

The computation of the j coordinate is similar.

Definition at line 325 of file vpPolygon.cpp.

References _area, _center, _corners, _goodPoly, vpImagePoint::set_i(), and vpImagePoint::set_j().

Referenced by init().

Member Data Documentation

double vpPolygon::_area

protected

Area of the polygon.

Definition at line 110 of file vpPolygon.h.

Referenced by operator=(), updateArea(), updateCenter(), and vpPolygon().

vpRect vpPolygon::_bbox

protected

Boumding box containing the polygon.

Definition at line 114 of file vpPolygon.h.

Referenced by updateBoundingBox().

vpImagePoint vpPolygon::_center

protected

Center of the polygon. It is automatically computed when the corners are set.

Definition at line 108 of file vpPolygon.h.

Referenced by operator=(), updateCenter(), and vpPolygon().

std::vector<vpImagePoint> vpPolygon::_corners

protected

Collection of image points containing the corners.

Definition at line 106 of file vpPolygon.h.

Referenced by display(), init(), isInside(), operator=(), updateArea(), updateBoundingBox(), updateCenter(), and vpPolygon().

bool vpPolygon::_goodPoly

protected

Flag to indicate whether the polygon is a good polygon (ie. it has more than two corners, ...)

Definition at line 112 of file vpPolygon.h.

Referenced by operator=(), updateArea(), updateBoundingBox(), updateCenter(), and vpPolygon().

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation