Method IntersectWithLine

Common/DataModel/vtkTriangle.cxx:547–693

------------------------------------------------------------------------------ Plane intersection plus in/out test on triangle. The in/out test is performed using tol as the tolerance.

// Plane intersection plus in/out test on triangle. The in/out test is
// performed using tol as the tolerance.
int vtkTriangle::IntersectWithLine(const double p1[3], const double p2[3], double tol, double& t,
  double x[3], double pcoords[3], int& subId)
{
  double closestPoint[3];
  double dist2 = 0.0;
  double tol2 = tol * tol;
  double weights[3];

  subId = 0;
  pcoords[2] = 0.0;

  // Get normal for triangle
  //
  double pt1[3];
  double pt2[3];
  double pt3[3];
  vtkPoints* points = this->Points;
  points->GetPoint(1, pt1);
  points->GetPoint(2, pt2);
  points->GetPoint(0, pt3);

  double n[3];
  vtkTriangle::ComputeNormal(pt1, pt2, pt3, n);

  if (n[0] != 0.0 || n[1] != 0.0 || n[2] != 0.0)
  {
    // Intersect plane of triangle with line
    //
    if (!vtkPlane::IntersectWithLine(p1, p2, n, pt1, t, x))
    {
      // If the line and the triangle are not parallel or not coplanar
      if (t != VTK_DOUBLE_MAX || (vtkMath::Dot(n, pt1) - vtkMath::Dot(n, p1)) != 0.0)
      {
        pcoords[0] = pcoords[1] = 0.0;
        return 0;
      }

      // When the line is coplanar with the triangle, the intersection point is chosen to be the
      // closest to p1.

      // If p1 is inside the triangle
      if (this->EvaluatePosition(p1, closestPoint, subId, pcoords, dist2, weights) == 1)
      {
        t = 0.0;
        x[0] = p1[0];
        x[1] = p1[1];
        x[2] = p1[2];
        return 1;
      }

      // If p1 is outside of the triangle
      bool intersection = false;
      double closestDistance = VTK_DOUBLE_MAX;
      double closestX[3] = { 0., 0., 0. };
      double closestPCoords[3] = { 0., 0., 0. };

      for (vtkIdType i = 0; i < this->GetNumberOfEdges(); i++)
      {