ossimLine Class Reference

#include <ossimLine.h>

Public Member Functions
	ossimLine (const ossimDpt &p1=ossimDpt(0, 0), const ossimDpt &p2=ossimDpt(0, 0))
ossimDpt	getVector () const
ossimDpt	intersectInfinite (const ossimLine &line) const
ossimDpt	intersectSegment (const ossimLine &line) const
ossimDpt	midPoint () const
double	length () const
ossimDpt	normal () const
bool	isPointWithin (const ossimDpt &point, double delta=FLT_EPSILON) const
bool	isPointOnInfiniteLine (const ossimDpt &point, double delta=FLT_EPSILON) const

Public Attributes
ossimDpt	theP1
ossimDpt	theP2

Friends
OSSIM_DLL std::ostream &	operator<< (std::ostream &out, const ossimLine &rhs)

Detailed Description

Definition at line 14 of file ossimLine.h.

Constructor & Destructor Documentation

ossimLine()

ossimLine::ossimLine ( const ossimDpt &  p1 = ossimDpt(0,0), const ossimDpt &  p2 = ossimDpt(0,0)  )

inline

Definition at line 19 of file ossimLine.h.

      :theP1(p1),
       theP2(p2)
      {
      }

Member Function Documentation

getVector()

ossimDpt ossimLine::getVector ( ) const

inline

Definition at line 27 of file ossimLine.h.

      {
         return (theP2-theP1);
      }

intersectInfinite()

ossimDpt ossimLine::intersectInfinite

(

const ossimLine &

line

)

const

Computes the following equation:

Note: this object will be line a and the passed in object will be line b; and P1 and P2 coorespond to this object and P3 and P4 will coorespond to the passed in object.

Now find point formed at the intersection of line a and b:

Pa = P1 + ua ( P2 - P1 ) Pb = P3 + ub ( P4 - P3 ) const ossimDpt& ul_corner, const ossimDpt& lr_corner, ossimCoordSysOrientMode mode=OSSIM_LEFT_HANDED); x1 + ua (x2 - x1) = x3 + ub (x4 - x3) and y1 + ua (y2 - y1) = y3 + ub (y4 - y3)

Solve: ua = ((x4-x3)(y1-y3) - (y4-y3)(x1-x3))/ ((y4-y3)(x2-x1) - (x4-x3)(y2-y1)) ub = ((x2-x1)(y1-y3) - (y2-y1)(x1-x3))/ ((y4-y3)(x2-x1) - (x4-x3)(y2-y1)) substitute:

x = x1 + ua (x2 - x1) y = y1 + ua (y2 - y1)

Definition at line 20 of file ossimLine.cpp.

References FLT_EPSILON, ossimDpt::makeNan(), theP1, theP2, ossimDpt::x, and ossimDpt::y.

Referenced by ossimFeatherMosaic::ossimFeatherInputInformation::setVertexList().

{
   ossimDpt result;
   ossimDpt p3 = line.theP1;
   ossimDpt p4 = line.theP2;

   double numerator  = ((p4.x-p3.x)*(theP1.y-p3.y)    - (p4.y-p3.y)*(theP1.x-p3.x));
   double denominator = ((p4.y-p3.y)*(theP2.x-theP1.x) - (p4.x-p3.x)*(theP2.y-theP1.y));
   result.makeNan();
   // as long as the lines are not parallel
   if(fabs(denominator) > FLT_EPSILON)
   {
      double ua = numerator/ denominator;
      result = ossimDpt(theP1.x + ua*(theP2.x-theP1.x),
                        theP1.y + ua*(theP2.y-theP1.y));
   }

   return result;
}

intersectSegment()

ossimDpt ossimLine::intersectSegment

(

const ossimLine &

line

)

const

Definition at line 40 of file ossimLine.cpp.

References FLT_EPSILON, length(), ossimDpt::makeNan(), theP1, theP2, ossimDpt::x, and ossimDpt::y.

{
   ossimDpt result;
   ossimDpt p3 = line.theP1;
   ossimDpt p4 = line.theP2;

   double numerator   = ((p4.x-p3.x)*(theP1.y-p3.y)    - (p4.y-p3.y)*(theP1.x-p3.x));
   double denominator = ((p4.y-p3.y)*(theP2.x-theP1.x) - (p4.x-p3.x)*(theP2.y-theP1.y));
   result.makeNan();
   // as long as the lines are not parallel
   if(fabs(denominator) > FLT_EPSILON)
   {
      double ua = numerator/ denominator;

      if((ua >= -FLT_EPSILON) && (ua <= (1.0 + FLT_EPSILON)))
      {
         ossimDpt test = ossimDpt(theP1.x + ua*(theP2.x-theP1.x),
                                  theP1.y + ua*(theP2.y-theP1.y));
         ossimDpt midPoint = line.theP1 + (line.theP2-line.theP1)*.5;
         if( ((test-midPoint).length()/line.length()) <= (.5+FLT_EPSILON))
         {
            result = test;
         }
      }
   }

   return result;
}

isPointOnInfiniteLine()

bool ossimLine::isPointOnInfiniteLine	(	const ossimDpt &	point,
		double	delta = FLT_EPSILON
	)		const

Definition at line 99 of file ossimLine.cpp.

References FLT_EPSILON, ossimDpt::length(), ossimDpt::x, and ossimDpt::y.

{
   if((point == theP1) || (point == theP2))
   {
      return true;
   }
   else if(fabs(theP1.x-theP2.x) <= FLT_EPSILON)
   {
      return (fabs(point.x - theP1.x) <= delta);
   }
   else if(fabs(theP1.y-theP2.y) <= FLT_EPSILON)
   {
      return (fabs(point.y - theP1.y) <= delta);      
   }
   else
   {
      ossimDpt v1  = getVector();
      v1 = v1 * (1.0/v1.length());
      ossimDpt v2  = (point - theP1);
      double s     = v1.x*v2.x + v1.y*v2.y;
      ossimDpt p   = theP1 + v1*s;
      double len   = (point-p).length();

      if(len < delta)
      {
         return true;
      }
      else
      {
         return false;
      }
   }

   return false;
}

isPointWithin()

bool ossimLine::isPointWithin	(	const ossimDpt &	point,
		double	delta = FLT_EPSILON
	)		const

Will return true if the point is on the line.

Definition at line 79 of file ossimLine.cpp.

References max, min, and ossimDrect::pointWithin().

Referenced by ossimPolyLine::isPointWithin().

{   
   if(isPointOnInfiniteLine(point, delta))
   {
      double minx = std::min(theP1.x, theP2.x);
      double miny = std::min(theP1.y, theP2.y);
      double maxx = std::max(theP1.x, theP2.x);
      double maxy = std::max(theP1.y, theP2.y);
      
      ossimDrect rect(minx - delta,
                      miny - delta,
                      maxx + delta,
                      maxy + delta);
      
      return rect.pointWithin(point);
   }
   
   return false;
}

length()

double ossimLine::length

(

)

const

Definition at line 69 of file ossimLine.cpp.

Referenced by intersectSegment().

{
   return (theP2-theP1).length();
}

midPoint()

ossimDpt ossimLine::midPoint

(

)

const

Definition at line 74 of file ossimLine.cpp.

{
   return (theP1 + (theP2-theP1)*.5);
}

normal()

ossimDpt ossimLine::normal

(

)

const

Definition at line 135 of file ossimLine.cpp.

References FLT_EPSILON, ossimDpt::length(), ossimDpt::x, and ossimDpt::y.

Referenced by ossimPolygon::clipLineSegment().

{
   ossimDpt delta = getVector();
   ossimDpt result;
   if(fabs(delta.x) <= FLT_EPSILON)
   {
      result.y = 0.0;
      result.x = -delta.y;
   }
   else if(fabs(delta.y) <= FLT_EPSILON)
   {
      result.x = 0.0;
      result.y = delta.x;
   }
   else
   {
      result.x = -delta.y;
      result.y = delta.x;
   }
   double len = result.length();
   
   if(len >FLT_EPSILON)
   {
      result = result*(1.0/len);
   }

   return result;
}

Friends And Related Function Documentation

operator<<

OSSIM_DLL std::ostream& operator<< ( std::ostream &  out, const ossimLine &  rhs  )

friend

Definition at line 15 of file ossimLine.cpp.

{
   return out << "line: " << rhs.theP1 << "," << rhs.theP2 << endl;
}

Member Data Documentation

theP1

ossimDpt ossimLine::theP1

Definition at line 77 of file ossimLine.h.

Referenced by ossimPolygon::clipLineSegment(), intersectInfinite(), intersectSegment(), and operator<<().

theP2

ossimDpt ossimLine::theP2

Definition at line 78 of file ossimLine.h.

Referenced by intersectInfinite(), intersectSegment(), and operator<<().

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

• ossimLine.h
• ossimLine.cpp