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Common/vtkTriangle.h

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

  Program:   Visualization Toolkit
  Module:    $RCSfile: vtkTriangle.h,v $
  Language:  C++


Copyright (c) 1993-2001 Ken Martin, Will Schroeder, Bill Lorensen 
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.

 * Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

 * Neither name of Ken Martin, Will Schroeder, or Bill Lorensen nor the names
   of any contributors may be used to endorse or promote products derived
   from this software without specific prior written permission.

 * Modified source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

=========================================================================*/
#ifndef __vtkTriangle_h
#define __vtkTriangle_h

#include "vtkCell.h"
#include "vtkMath.h"
#include "vtkLine.h"
#include "vtkQuadric.h"

class VTK_COMMON_EXPORT vtkTriangle : public vtkCell
{
public:
  static vtkTriangle *New();
  vtkTypeMacro(vtkTriangle,vtkCell);

  vtkCell *MakeObject();

  vtkCell *GetEdge(int edgeId);


  int GetCellType() {return VTK_TRIANGLE;};
  int GetCellDimension() {return 2;};
  int GetNumberOfEdges() {return 3;};
  int GetNumberOfFaces() {return 0;};
  vtkCell *GetFace(int) {return 0;};
  int CellBoundary(int subId, float pcoords[3], vtkIdList *pts);
  void Contour(float value, vtkDataArray *cellScalars, 
               vtkPointLocator *locator, vtkCellArray *verts,
               vtkCellArray *lines, vtkCellArray *polys, 
               vtkPointData *inPd, vtkPointData *outPd,
               vtkCellData *inCd, vtkIdType cellId, vtkCellData *outCd);
  int EvaluatePosition(float x[3], float* closestPoint,
                       int& subId, float pcoords[3],
                       float& dist2, float *weights);
  void EvaluateLocation(int& subId, float pcoords[3], float x[3],
                        float *weights);
  int Triangulate(int index, vtkIdList *ptIds, vtkPoints *pts);
  void Derivatives(int subId, float pcoords[3], float *values, 
                   int dim, float *derivs);


  void Clip(float value, vtkDataArray *cellScalars, 
            vtkPointLocator *locator, vtkCellArray *polys,
            vtkPointData *inPd, vtkPointData *outPd,
            vtkCellData *inCd, vtkIdType cellId, vtkCellData *outCd,
            int insideOut);


  int IntersectWithLine(float p1[3], float p2[3], float tol, float& t,
                        float x[3], float pcoords[3], int& subId);

  int GetParametricCenter(float pcoords[3]);


  static void TriangleCenter(float p1[3], float p2[3], float p3[3], 
                             float center[3]);

  static float TriangleArea(float p1[3], float p2[3], float p3[3]);
  

  static double Circumcircle(double  p1[2], double p2[2], double p3[2], 
                            double center[2]);


  static int BarycentricCoords(double x[2], double  x1[2], double x2[2], 
                               double x3[2], double bcoords[3]);
  
  

  static int ProjectTo2D(double x1[3], double x2[3], double x3[3],
                         double v1[2], double v2[2], double v3[2]);


  static void ComputeNormal(vtkPoints *p, int numPts, vtkIdType *pts,
                            float n[3]);

  static void ComputeNormal(float v1[3], float v2[3], float v3[3], float n[3]);


  static void ComputeNormalDirection(float v1[3], float v2[3], float v3[3],
                                     float n[3]);
  

  static void ComputeNormal(double v1[3], double v2[3], double v3[3], 
                            double n[3]);
  

  static void ComputeNormalDirection(double v1[3], double v2[3], double v3[3],
                                     double n[3]);


  static int PointInTriangle(float x[3], float x1[3], float x2[3], float x3[3], 
                             float tol2);


  static void ComputeQuadric(float x1[3], float x2[3], float x3[3],
                             float quadric[4][4]);
  static void ComputeQuadric(float x1[3], float x2[3], float x3[3],
                             vtkQuadric *quadric);
  

protected:
  vtkTriangle();
  ~vtkTriangle();

  vtkLine *Line;

private:
  vtkTriangle(const vtkTriangle&);  // Not implemented.
  void operator=(const vtkTriangle&);  // Not implemented.
};

inline int vtkTriangle::GetParametricCenter(float pcoords[3])
{
  pcoords[0] = pcoords[1] = 0.333; pcoords[2] = 0.0;
  return 0;
}

inline void vtkTriangle::ComputeNormalDirection(float v1[3], float v2[3], 
                                       float v3[3], float n[3])
{
  float ax, ay, az, bx, by, bz;

  // order is important!!! maintain consistency with triangle vertex order 
  ax = v3[0] - v2[0]; ay = v3[1] - v2[1]; az = v3[2] - v2[2];
  bx = v1[0] - v2[0]; by = v1[1] - v2[1]; bz = v1[2] - v2[2];

  n[0] = (ay * bz - az * by);
  n[1] = (az * bx - ax * bz);
  n[2] = (ax * by - ay * bx);
}

inline void vtkTriangle::ComputeNormal(float v1[3], float v2[3], 
                                       float v3[3], float n[3])
{
  float length;
  
  vtkTriangle::ComputeNormalDirection(v1, v2, v3, n);
  
  if ( (length = sqrt((n[0]*n[0] + n[1]*n[1] + n[2]*n[2]))) != 0.0 )
    {
    n[0] /= length;
    n[1] /= length;
    n[2] /= length;
    }
}

inline void vtkTriangle::ComputeNormalDirection(double v1[3], double v2[3], 
                                       double v3[3], double n[3])
{
  double ax, ay, az, bx, by, bz;

  // order is important!!! maintain consistency with triangle vertex order 
  ax = v3[0] - v2[0]; ay = v3[1] - v2[1]; az = v3[2] - v2[2];
  bx = v1[0] - v2[0]; by = v1[1] - v2[1]; bz = v1[2] - v2[2];

  n[0] = (ay * bz - az * by);
  n[1] = (az * bx - ax * bz);
  n[2] = (ax * by - ay * bx);
}

inline void vtkTriangle::ComputeNormal(double v1[3], double v2[3], 
                                       double v3[3], double n[3])
{
  double length;

  vtkTriangle::ComputeNormalDirection(v1, v2, v3, n);

  if ( (length = sqrt((n[0]*n[0] + n[1]*n[1] + n[2]*n[2]))) != 0.0 )
    {
    n[0] /= length;
    n[1] /= length;
    n[2] /= length;
    }
}

inline void vtkTriangle::TriangleCenter(float p1[3], float p2[3], float p3[3],
                                       float center[3])
{
  center[0] = (p1[0]+p2[0]+p3[0]) / 3.0;
  center[1] = (p1[1]+p2[1]+p3[1]) / 3.0;
  center[2] = (p1[2]+p2[2]+p3[2]) / 3.0;
}

inline float vtkTriangle::TriangleArea(float p1[3], float p2[3], float p3[3])
{
  float a,b,c;
  a = vtkMath::Distance2BetweenPoints(p1,p2);
  b = vtkMath::Distance2BetweenPoints(p2,p3);
  c = vtkMath::Distance2BetweenPoints(p3,p1);
  return (0.25* sqrt(fabs((double)4.0*a*c - (a-b+c)*(a-b+c))));
} 

#endif

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