2D line segment More...

#include <laLine2.h>

Public Member Functions
laPoint2	normal (int direction=1) const
	Get a perpendicular vector of lenght 1 (normal of the line segment)

int	direction (const laPoint2 &pt) const

M_BOOL	onSameSide (const laPoint2 &a, const laPoint2 &b) const
	Check if two points are on the same side of the line.

M_BOOL	intersection (const laLine2 &ln, double k, double k_ln) const

double	distance (laPoint2 &pt) const
	Compute the distance between a point and the line.

double	distance_sq (laPoint2 &pt) const
	Compute the square of the distance between a point and the line.

void	draw (class laRenderer *r, laPoint2 &pos)
	Draw the line ( primarily for debug purposes )

Line constructors and initialization methods
	laLine2 (void)

	laLine2 (const laPoint2 &a, const laPoint2 &b)

void	build (const laPoint2 &a, const laPoint2 &b)
	Build a line from two end-points.

void	build_v (const laPoint2 &a, const laPoint2 &v)
	Build a line from an end-point and a vector.

Lenght of the segment
double	lenght () const

double	lenght_sq () const
	Squared root of segment lenght.

Getting points at different positions on the line
laPoint2	end () const
	Get the end-point.

void	at (double k, laPoint2 *ppt) const
	Get point at 1/k lenght (returns in user-specified pointer) More...

const laPoint2	at (double k) const

double	getX (double k) const
	Get X at 1/k lenght.

double	getY (double k) const
	Get Y at 1/k lenght.

Getting the parameter k at specified XY coordinates
double	getK (const laPoint2 &pt) const

double	getK_atX (double x) const

double	getK_atY (double y) const

Static Public Member Functions
static void	drawLine2s (laLine2 arLines, unsigned n, class laRenderer r, laPoint2 &pos)
	Draw many lines ( primarily for debug purposes )

Public Attributes
laPoint2	origin
	Point of origin.

laPoint2	vector
	Vector ( not normalized, so k = [0;1] traces the whole line segment )

Detailed Description

2D line segment

Author: Atanas Laskov

Definition at line 40 of file laLine2.h.

Member Function Documentation

void laLine2::at	(	double	k,
		laPoint2 *	ppt
	)		const

inline

Get point at 1/k lenght (returns in user-specified pointer)

Get point at 1/k lenght (retruns a new object)

Definition at line 81 of file laLine2.h.

Referenced by distance(), distance_sq(), and intersection().

int laLine2::direction ( const laPoint2 & pt ) const

inline

Get {+1; -1} depending on the side of the line where a point resides. NOTE: This can be used to reason about the relative position of two points

Definition at line 123 of file laLine2.h.

Referenced by normal(), and onSameSide().

                                                    {
         PROFILE_COL(laPoint2_direction);
         double k;// = getK(pt.x());
 
         if( M_ABS( vector.x() )>M_ABS( vector.y() ) )
         {
             k = getK_atX( pt.x() );
             return ( getY(k) > pt.y() ) ? +1 : -1;
         }
         else
         {
             k = getK_atY( pt.y() );
             return ( getX(k) > pt.x() ) ? +1 : -1;
         }
     }

M_BOOL laLine2::intersection	(	const laLine2 &	ln,
		double *	k,
		double *	k_ln
	)		const

inline

Find the point of intersection with another line segment; If the vectors are parallel, returns false; Otherwise returns parameters k and k_ln, corresponding to positions along the two line segments.

Definition at line 149 of file laLine2.h.

Referenced by distance(), and distance_sq().

                                                                                  {
         //PROFILE_COL(laLine2_intersection);
         //ASSERT(k && k_ln, "Nil k or k_ln recepient ptr");
         double dCross1 = vector.cross( ln.vector );
 
         if( M_ABS(dCross1) < 0.00001) return M_FALSE;       // parallel vectors?
 
         // ln.origin.cross( ln.vector ) - origin.cross( ln.vec )
         *k = ( (ln.origin.x() - origin.x())*ln.vector.y() + (origin.y() - ln.origin.y())*ln.vector.x() ) / dCross1;
         *k_ln = ln.getK( at(*k) );
 
         return M_TRUE;
     }

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

Source/Core/laLine2.h
Source/Core/laLine2.cpp

Public Member Functions

Static Public Member Functions

Public Attributes

Detailed Description

Member Function Documentation