/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkPolygon.h
  Language:  C++
  Date:      $Date$
  Version:   $Revision$


Copyright (c) 1993-1998 Ken Martin, Will Schroeder, Bill Lorensen.

This software is copyrighted by Ken Martin, Will Schroeder and Bill Lorensen.
The following terms apply to all files associated with the software unless
explicitly disclaimed in individual files. This copyright specifically does
not apply to the related textbook "The Visualization Toolkit" ISBN
013199837-4 published by Prentice Hall which is covered by its own copyright.

The authors hereby grant permission to use, copy, and distribute this
software and its documentation for any purpose, provided that existing
copyright notices are retained in all copies and that this notice is included
verbatim in any distributions. Additionally, the authors grant permission to
modify this software and its documentation for any purpose, provided that
such modifications are not distributed without the explicit consent of the
authors and that existing copyright notices are retained in all copies. Some
of the algorithms implemented by this software are patented, observe all
applicable patent law.

IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF,
EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE IS PROVIDED ON AN
"AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.


=========================================================================*/
// .NAME vtkPolygon - a cell that represents an n-sided polygon
// .SECTION Description
// vtkPolygon is a concrete implementation of vtkCell to represent a 2D 
// n-sided polygon. The polygons cannot have any internal holes, and cannot
// self-intersect.

#ifndef __vtkPolygon_h
#define __vtkPolygon_h

#include "vtkCell.h"
#include "vtkPoints.h"
#include "vtkLine.h"
#include "vtkTriangle.h"

class VTK_EXPORT vtkPolygon : public vtkCell
{
public:
  vtkPolygon();
  ~vtkPolygon();
  static vtkPolygon *New() {return new vtkPolygon;};
  const char *GetClassName() {return "vtkPolygon";};

  // Description:
  // See the vtkCell API for descriptions of these methods.
  vtkCell *MakeObject();
  int GetCellType() {return VTK_POLYGON;};
  int GetCellDimension() {return 2;};
  int GetNumberOfEdges() {return this->GetNumberOfPoints();};
  int GetNumberOfFaces() {return 0;};
  vtkCell *GetEdge(int edgeId);
  vtkCell *GetFace(int) {return 0;};
  int CellBoundary(int subId, float pcoords[3], vtkIdList *pts);
  void Contour(float value, vtkScalars *cellScalars, 
               vtkPointLocator *locator,vtkCellArray *verts, 
               vtkCellArray *lines, vtkCellArray *polys,
               vtkPointData *inPd, vtkPointData *outPd,
               vtkCellData *inCd, int cellId, vtkCellData *outCd);
  void Clip(float value, vtkScalars *cellScalars, 
            vtkPointLocator *locator, vtkCellArray *tris,
            vtkPointData *inPd, vtkPointData *outPd,
            vtkCellData *inCd, int cellId, vtkCellData *outCd, int insideOut);
  int EvaluatePosition(float x[3], float closestPoint[3],
                       int& subId, float pcoords[3],
                       float& dist2, float *weights);
  void EvaluateLocation(int& subId, float pcoords[3], float x[3],
                        float *weights);
  int IntersectWithLine(float p1[3], float p2[3], float tol, float& t,
                        float x[3], float pcoords[3], int& subId);
  int Triangulate(int index, vtkIdList *ptIds, vtkPoints *pts);
  void Derivatives(int subId, float pcoords[3], float *values, 
                   int dim, float *derivs);

  // Description:
  // Polygon specific
  static void ComputeNormal(vtkPoints *p, int numPts, int *pts, float n[3]);
  static void ComputeNormal(vtkPoints *p, float n[3]);
  
  // Description:
  // Compute the polygon normal from an array of points. This version assumes
  // that the polygon is convex, and looks for the first valid normal.
  static void ComputeNormal(int numPts, float *pts, float n[3]);

  // Description:
  // Compute interpolation weights using 1/r**2 normalized sum.
  void ComputeWeights(float x[3], float *weights);


  // Description:
  // Create a local s-t coordinate system for a polygon. The point p0 is
  // the origin of the local system, p10 is s-axis vector, and p20 is the 
  // t-axis vector. (These are expressed in the modelling coordinate system and
  // are vectors of dimension [3].) The values l20 and l20 are the lengths of
  // the vectors p10 and p20, and n is the polygon normal.
  int ParameterizePolygon(float p0[3], float p10[3], float &l10, 
                          float p20[3], float &l20, float n[3]);
  
  // Description:
  // Determine whether point is inside polygon. Function uses ray-casting
  // to determine if point is inside polygon. Works for arbitrary polygon shape
  // (e.g., non-convex). Returns 0 if point is not in polygon; 1 if it is.
  // Can also return -1 to indicate degenerate polygon.
  static int PointInPolygon(float x[3], int numPts, float *pts, 
			    float bounds[6], float n[3]);  

  // Description:
  // Triangulate polygon. Tries to use the fast triangulation technique 
  // first, and if that doesn't work, uses more complex routine that is
  //  guaranteed to work.
  int Triangulate(vtkIdList *outTris);
  
  // Description: 
  // A fast triangulation method. Uses recursive divide and 
  // conquer based on plane splitting  to reduce loop into triangles.  
  // The cell (e.g., triangle) is presumed properly initialized (i.e., 
  // Points and PointIds).
  int RecursiveTriangulate(int numVerts, int *verts);

  // Description:
  // Determine whether the loop can be split. Determines this by first checking
  // to see whether points in each loop are on opposite sides of the split
  // plane. If so, then the loop can be split; otherwise see whether one of the
  // loops has all its points on one side of the split plane and the split line
  // is inside the polygon.
  int CanSplitLoop(int fedges[2], int numVerts, int *verts, int& n1, int *l1,
                   int& n2, int *l2);

  // Description:
  // Creates two loops from splitting plane provided
  void SplitLoop (int fedges[2], int numVerts, int *verts, int& n1, int *l1, 
                  int& n2, int* l2);


  // Description:
  // Method intersects two polygons. You must supply the number of points and
  // point coordinates (npts, *pts) and the bounding box (bounds) of the two
  // polygons. Also supply a tolerance squared for controlling
  // error. The method returns 1 if there is an intersection, and 0 if
  // not. A single point of intersection x[3] is also returned if there
  // is an intersection.
  static int IntersectPolygonWithPolygon(int npts, float *pts, float bounds[6],
                                         int npts2, float *pts2, 
                                         float bounds2[3], float tol,
                                         float x[3]);

  // Description:
  // For legacy compatibility. Do not use.
  int CellBoundary(int subId, float pcoords[3], vtkIdList &pts)
    {return this->CellBoundary(subId, pcoords, &pts);}
  int Triangulate(int index, vtkIdList &ptIds, vtkPoints &pts)
    {return this->Triangulate(index, &ptIds, &pts);}
  int Triangulate(vtkIdList &outTris){return this->Triangulate(&outTris);}
  

protected:
  // variables used by instances of this class
  float   Tolerance; // Intersection tolerance
  int     SuccessfulTriangulation; // Stops recursive tri. if necessary
  float   Normal[3]; //polygon normal
  vtkIdList *Tris;
  vtkTriangle *Triangle;
  vtkScalars *TriScalars;
  vtkLine *Line;

};

#endif

