Method IntersectConvex2DCells

Common/DataModel/vtkPolygon.cxx:2398–2462

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int vtkPolygon::IntersectConvex2DCells(
  vtkCell* cell1, vtkCell* cell2, double tol, double p0[3], double p1[3])
{
  // Intersect the six total edges of the two triangles against each other. Two points are
  // all that are required.
  double *x[2], pcoords[3], t, x0[3], x1[3];
  x[0] = p0;
  x[1] = p1;
  int subId, idx = 0;
  double t2 = tol * tol;

  // Loop over edges of second polygon and intersect against first polygon
  vtkIdType i, numPts = cell2->Points->GetNumberOfPoints();
  for (i = 0; i < numPts; i++)
  {
    cell2->Points->GetPoint(i, x0);
    cell2->Points->GetPoint((i + 1) % numPts, x1);

    if (cell1->IntersectWithLine(x0, x1, tol, t, x[idx], pcoords, subId))
    {
      if (idx == 0)
      {
        idx++;
      }
      else if (((x[1][0] - x[0][0]) * (x[1][0] - x[0][0]) +
                 (x[1][1] - x[0][1]) * (x[1][1] - x[0][1]) +
                 (x[1][2] - x[0][2]) * (x[1][2] - x[0][2])) > t2)
      {
        return 2;
      }
    } // if edge intersection
  }   // over all edges

  // Loop over edges of first polygon and intersect against second polygon
  numPts = cell1->Points->GetNumberOfPoints();
  for (i = 0; i < numPts; i++)
  {
    cell1->Points->GetPoint(i, x0);
    cell1->Points->GetPoint((i + 1) % numPts, x1);

    if (cell2->IntersectWithLine(x0, x1, tol, t, x[idx], pcoords, subId))
    {
      if (idx == 0)
      {
        idx++;
      }
      else if (((x[1][0] - x[0][0]) * (x[1][0] - x[0][0]) +
                 (x[1][1] - x[0][1]) * (x[1][1] - x[0][1]) +
                 (x[1][2] - x[0][2]) * (x[1][2] - x[0][2])) > t2)
      {
        return 2;
      }
    } // if edge intersection
  }   // over all edges

  // Evaluate what we got
  if (idx == 1)
  {