CubitPolygon Class Reference

#include <CubitPolygon.hpp>

List of all members.

Public Member Functions
	CubitPolygon ()
	CubitPolygon (DLIList< Cubit2DPoint * > &point_list)
	CubitPolygon (Cubit2DPoint &point)
	~CubitPolygon ()
void	add_point (Cubit2DPoint &point)
CubitPointContainment	pnt_containment (Cubit2DPoint &point, double tol=1e-10)
CubitStatus	centroid_area (Cubit2DPoint &centroid, double &area)
Private Attributes
DLIList< Cubit2DPoint * >	pointList
Cubit2DPoint	minCoord
Cubit2DPoint	maxCoord

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Detailed Description

Definition at line 16 of file CubitPolygon.hpp.

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Constructor & Destructor Documentation

CubitPolygon::CubitPolygon

(

)

Definition at line 10 of file CubitPolygon.cpp.

{
}

CubitPolygon::CubitPolygon

(

DLIList< Cubit2DPoint * > &

point_list

)

Definition at line 19 of file CubitPolygon.cpp.

{
   int i;
   point_list.reset();
   for ( i = point_list.size(); i--; )
   {
      Cubit2DPoint *pnt = point_list.get_and_step();         
      add_point( *pnt );
   }
}

CubitPolygon::CubitPolygon

(

Cubit2DPoint &

point

)

Definition at line 14 of file CubitPolygon.cpp.

{
   add_point( start_pnt );
}

CubitPolygon::~CubitPolygon

(

)

Definition at line 30 of file CubitPolygon.cpp.

{
   int i;
   for ( i = pointList.size(); i--; )
      delete pointList.get_and_step();
}

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Member Function Documentation

void CubitPolygon::add_point

(

Cubit2DPoint &

point

)

Definition at line 38 of file CubitPolygon.cpp.

{

   // Add the point
   pointList.append( new Cubit2DPoint( new_pnt ) );
   
   // Update bounding box
   if( pointList.size() == 1 )
   {
      minCoord = new_pnt;
      maxCoord = new_pnt;
   }
   else
      new_pnt.update_min_max( minCoord, maxCoord );
}

CubitStatus CubitPolygon::centroid_area	(	Cubit2DPoint &	centroid,
		double &	area
	)

Definition at line 123 of file CubitPolygon.cpp.

{
  // Algorithm from Graphics Gems
  int n = pointList.size();

  if( pointList.size() < 3 )
    return CUBIT_FAILURE;

  double ai, atmp = 0.0, xtmp = 0.0, ytmp = 0.0;

  Cubit2DPoint *p1, *p2;
  pointList.reset();
  for (int j = 0; j < n; j++)
  {
    p1 = pointList.get_and_step();
    p2 = pointList.get();
    ai = p1->x() * p2->y() - p2->x() * p1->y();
    atmp += ai;
    xtmp += ( p2->x() + p1->x() ) * ai;
    ytmp += ( p2->y() + p1->y() ) * ai;
  }

  area = atmp / 2.0;
  if (atmp != 0.0)
  {
    centroid.set( xtmp / (3.0 * atmp), ytmp / (3.0 * atmp) );
    return CUBIT_SUCCESS;
  }

  return CUBIT_FAILURE;
}

CubitPointContainment CubitPolygon::pnt_containment	(	Cubit2DPoint &	point,
		double	tol = 1e-10
	)

Definition at line 55 of file CubitPolygon.cpp.

{
   // Method is to fire a ray in negative x-direction and check the number
   // of intersections with the polygon.  Odd - in the loop, Even - outside
   // of the loop.
   
   // Returns: CubitPointContainment ( CUBIT_PNT_OUTSIDE = 0, 
   //                                  CUBIT_PNT_INSIDE = 1, 
   //                                  CUBIT_PNT_BOUNDARY = 2 )
   
   int i,
      c = 0; // Check variable
   
   // First check to see if the point is outside of the bounding box
   // of the polygon - if so, return OUT.
   
   if( pnt.x() < minCoord.x()-tol || pnt.y() < minCoord.y()-tol ||
      pnt.x() > maxCoord.x()+tol || pnt.y() > maxCoord.y()+tol ) 
   {
      return CUBIT_PNT_OUTSIDE;
   }
   
   // Loop on line segments of this polygon
   Cubit2DPoint *start_pnt, *end_pnt;
   pointList.reset();
   for ( i=pointList.size(); i--; )
   {
     start_pnt = pointList.get_and_step();
     end_pnt = pointList.get();

     // Check if point lies on the line segment.  This is necessary because
     // the "fire-ray" code which checks if the point is inside or outside 
     // the polygon would return outside if the point is on the boundary.
     if( pnt.is_on_line_segment( start_pnt, end_pnt, tol ) )
       return CUBIT_PNT_BOUNDARY;

     // Check if point is in bounds of y of current segment (is it a 
       // candidate to cross segment?)
     if( (start_pnt->y() <= pnt.y() && pnt.y() < end_pnt->y()) ||
         (end_pnt->y() <= pnt.y() && pnt.y() < start_pnt->y()) )
     {
       // It's a candidate
       // Check if ray fired in negative x-direction crosses segment
       
       if( pnt.x() < (end_pnt->x()-start_pnt->x()) * (pnt.y()-start_pnt->y()) / 
           (end_pnt->y()-start_pnt->y()) + start_pnt->x() ) 
       {
         
         // Keeps track of even or odd number of crossings.
         //  0-even
         //  1-odd
         
         c = !c;
         
       }
     }
   }
   
   if( c )
      // Odd number of crossings
      return CUBIT_PNT_INSIDE;
   else
      // Even number of crossings
      return CUBIT_PNT_OUTSIDE;
}

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Member Data Documentation

Cubit2DPoint CubitPolygon::maxCoord [private]

Definition at line 47 of file CubitPolygon.hpp.

Cubit2DPoint CubitPolygon::minCoord [private]

Definition at line 46 of file CubitPolygon.hpp.

DLIList<Cubit2DPoint*> CubitPolygon::pointList [private]

Definition at line 45 of file CubitPolygon.hpp.

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

• CubitPolygon.hpp
• CubitPolygon.cpp