Method IntersectWithLine

Common/DataModel/vtkPixel.cxx:432–507

------------------------------------------------------------------------------ Intersect plane; see whether point is inside.

// Intersect plane; see whether point is inside.
//
int vtkPixel::IntersectWithLine(const double p1[3], const double p2[3], double tol, double& t,
  double x[3], double pcoords[3], int& subId)
{
  subId = 0;
  pcoords[0] = pcoords[1] = pcoords[2] = 0.0;
  double pt1[3], pt4[3];
  this->Points->GetPoint(0, pt1);
  this->Points->GetPoint(3, pt4);

  //
  // Get normal for triangle
  //
  double n[3] = { 0.0, 0.0, 0.0 };
  for (int i = 0; i < 3; i++)
  {
    if ((pt4[i] - pt1[i]) <= 0.0)
    {
      n[i] = 1.0;
      break;
    }
  }

  // Because vtkPlane::IntersectWithLine cannot handle intersection with finite
  // plane, we need to handle the coplanar case ourself and find the closest x/t possible.
  // EvaluatePosition will take care of filling values for subId and pcoords.
  const double v1[3] = { p1[0] - pt1[0], p1[1] - pt1[1], p1[2] - pt1[2] };
  const double v2[3] = { p2[0] - pt1[0], p2[1] - pt1[1], p2[2] - pt1[2] };
  bool isCoplanar = (std::abs(vtkMath::Dot(v1, n)) < tol) && (std::abs(vtkMath::Dot(v2, n)) < tol);
  if (isCoplanar)
  {
    // if p1 is inside the pixel then return p1.
    if (p1[0] <= pt4[0] && p1[0] >= pt1[0] && p1[1] <= pt4[1] && p1[1] >= pt1[1] &&
      p1[2] <= pt4[2] && p1[2] >= pt1[2])
    {
      t = 0;
      x[0] = p1[0];
      x[1] = p1[1];
      x[2] = p1[2];
    }
    // Else we check if we intersect any edges. If we dont that means we do not intersect the pixel.
    else
    {
      double mint = VTK_DOUBLE_MAX;
      double tmpt, tmpx[3], tmppcoords[3];
      int tmpid;
      for (int i = 0; i < 4; ++i)
      {
        bool res = this->GetEdge(i)->IntersectWithLine(p1, p2, tol, tmpt, tmpx, tmppcoords, tmpid);
        if (res && (tmpt < mint))
        {
          mint = tmpt;
          t = tmpt;
          x[0] = tmpx[0];
          x[1] = tmpx[1];
          x[2] = tmpx[2];
        }
      }