vtkTriangle.h

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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#ifndef vtkTriangle_h
#define vtkTriangle_h
 
#include "vtkCell.h"
#include "vtkCommonDataModelModule.h" // For export macro
 
#include "vtkMath.h" // Needed for inline methods
 
VTK_ABI_NAMESPACE_BEGIN
class vtkLine;
class vtkQuadric;
class vtkIncrementalPointLocator;
 
class VTKCOMMONDATAMODEL_EXPORT vtkTriangle : public vtkCell
{
public:
  static vtkTriangle* New();
  vtkTypeMacro(vtkTriangle, vtkCell);
  void PrintSelf(ostream& os, vtkIndent indent) override;
 
  vtkCell* GetEdge(int edgeId) override;
 
 
  int GetCellType() override { return VTK_TRIANGLE; }
  int GetCellDimension() override { return 2; }
  int GetNumberOfEdges() override { return 3; }
  int GetNumberOfFaces() override { return 0; }
  vtkCell* GetFace(int) override { return nullptr; }
  int CellBoundary(int subId, const double pcoords[3], vtkIdList* pts) override;
  void Contour(double value, vtkDataArray* cellScalars, vtkIncrementalPointLocator* locator,
    vtkCellArray* verts, vtkCellArray* lines, vtkCellArray* polys, vtkPointData* inPd,
    vtkPointData* outPd, vtkCellData* inCd, vtkIdType cellId, vtkCellData* outCd) override;
  int EvaluatePosition(const double x[3], double closestPoint[3], int& subId, double pcoords[3],
    double& dist2, double weights[]) override;
  void EvaluateLocation(int& subId, const double pcoords[3], double x[3], double* weights) override;
  int Triangulate(int index, vtkIdList* ptIds, vtkPoints* pts) override;
  void Derivatives(
    int subId, const double pcoords[3], const double* values, int dim, double* derivs) override;
  double* GetParametricCoords() override;
 
  double ComputeArea();
 
  void Clip(double value, vtkDataArray* cellScalars, vtkIncrementalPointLocator* locator,
    vtkCellArray* polys, vtkPointData* inPd, vtkPointData* outPd, vtkCellData* inCd,
    vtkIdType cellId, vtkCellData* outCd, int insideOut) override;
 
  static void InterpolationFunctions(const double pcoords[3], double sf[3]);
  static void InterpolationDerivs(const double pcoords[3], double derivs[6]);
 
  void InterpolateFunctions(const double pcoords[3], double sf[3]) override
  {
    vtkTriangle::InterpolationFunctions(pcoords, sf);
  }
  void InterpolateDerivs(const double pcoords[3], double derivs[6]) override
  {
    vtkTriangle::InterpolationDerivs(pcoords, derivs);
  }
 
  const vtkIdType* GetEdgeArray(vtkIdType edgeId);
 
  int IntersectWithLine(const double p1[3], const double p2[3], double tol, double& t, double x[3],
    double pcoords[3], int& subId) override;
 
  int GetParametricCenter(double pcoords[3]) override;
 
  double GetParametricDistance(const double pcoords[3]) override;
 
  static void TriangleCenter(
    const double p1[3], const double p2[3], const double p3[3], double center[3]);
 
  static double TriangleArea(const double p1[3], const double p2[3], const double p3[3]);
 
  static double Circumcircle(
    const double p1[2], const double p2[2], const double p3[2], double center[2]);
 
  static int BarycentricCoords(const double x[2], const double x1[2], const double x2[2],
    const double x3[2], double bcoords[3]);
 
  static int ProjectTo2D(const double x1[3], const double x2[3], const double x3[3], double v1[2],
    double v2[2], double v3[2]);
 
  static void ComputeNormal(vtkPoints* p, int numPts, const vtkIdType* pts, double n[3]);
 
  static void ComputeNormal(
    const double v1[3], const double v2[3], const double v3[3], double n[3]);
 
  static void ComputeNormalDirection(
    const double v1[3], const double v2[3], const double v3[3], double n[3]);
 
  // Description:
  // Determine whether or not triangle (p1,q1,r1) intersects triangle
  // (p2,q2,r2). This method is adapted from Olivier Devillers, Philippe Guigue.
  // Faster Triangle-Triangle Intersection Tests. RR-4488, IN-RIA. 2002.
  // <inria-00072100>.
  static int TrianglesIntersect(const double p1[3], const double q1[3], const double r1[3],
    const double p2[3], const double q2[3], const double r2[3]);
 
  // Description:
  // Given a point x, determine whether it is inside (within the
  // tolerance squared, tol2) the triangle defined by the three
  // coordinate values p1, p2, p3. Method is via comparing dot products.
  // (Note: in current implementation the tolerance only works in the
  // neighborhood of the three vertices of the triangle.
  static int PointInTriangle(
    const double x[3], const double x1[3], const double x2[3], const double x3[3], double tol2);
 
 
  static void ComputeQuadric(
    const double x1[3], const double x2[3], const double x3[3], double quadric[4][4]);
  static void ComputeQuadric(
    const double x1[3], const double x2[3], const double x3[3], vtkQuadric* quadric);
 
  static bool ComputeCentroid(vtkPoints* points, const vtkIdType* pointIds, double centroid[3]);
 
protected:
  vtkTriangle();
  ~vtkTriangle() override;
 
  vtkLine* Line;
 
private:
  vtkTriangle(const vtkTriangle&) = delete;
  void operator=(const vtkTriangle&) = delete;
};
 
//----------------------------------------------------------------------------
inline int vtkTriangle::GetParametricCenter(double pcoords[3])
{
  pcoords[0] = pcoords[1] = 1.0 / 3.0;
  pcoords[2] = 0.0;
  return 0;
}
 
//----------------------------------------------------------------------------
inline void vtkTriangle::ComputeNormalDirection(
  const double v1[3], const double v2[3], const double v3[3], double n[3])
{
  // order is important!!! maintain consistency with triangle vertex order
  double ax = v3[0] - v2[0];
  double ay = v3[1] - v2[1];
  double az = v3[2] - v2[2];
  double bx = v1[0] - v2[0];
  double by = v1[1] - v2[1];
  double 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(
  const double v1[3], const double v2[3], const double v3[3], double n[3])
{
  vtkTriangle::ComputeNormalDirection(v1, v2, v3, n);
 
  double length = sqrt(n[0] * n[0] + n[1] * n[1] + n[2] * n[2]);
  if (length != 0.0)
  {
    n[0] /= length;
    n[1] /= length;
    n[2] /= length;
  }
}
 
//----------------------------------------------------------------------------
inline void vtkTriangle::TriangleCenter(
  const double p1[3], const double p2[3], const double p3[3], double 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 double vtkTriangle::TriangleArea(const double p1[3], const double p2[3], const double p3[3])
{
  double n[3];
  vtkTriangle::ComputeNormalDirection(p1, p2, p3, n);
 
  return 0.5 * vtkMath::Norm(n);
}
 
VTK_ABI_NAMESPACE_END
#endif