Method Clip

Common/DataModel/vtkTriangle.cxx:985–1094

------------------------------------------------------------------------------ Clip this triangle using scalar value provided. Like contouring, except that it cuts the triangle to produce other triangles.

// Clip this triangle using scalar value provided. Like contouring, except
// that it cuts the triangle to produce other triangles.
void vtkTriangle::Clip(double value, vtkDataArray* cellScalars, vtkIncrementalPointLocator* locator,
  vtkCellArray* tris, vtkPointData* inPd, vtkPointData* outPd, vtkCellData* inCd, vtkIdType cellId,
  vtkCellData* outCd, int insideOut)
{
  constexpr int CASE_MASK[3] = { 1, 2, 4 };
  const TRIANGLE_CASES* triangleCase;
  const TRIANGLE_EDGE_LIST* edge;
  int i, index;
  const vtkIdType* vert;
  int e1, e2, newCellId;
  vtkIdType pts[3];
  int vertexId;
  double t, x1[3], x2[3], x[3], deltaScalar;

  // Build the case table
  if (insideOut)
  {
    for (i = 0, index = 0; i < 3; i++)
    {
      if (cellScalars->GetComponent(i, 0) <= value)
      {
        index |= CASE_MASK[i];
      }
    }
  }
  else
  {
    for (i = 0, index = 0; i < 3; i++)
    {
      if (cellScalars->GetComponent(i, 0) > value)
      {
        index |= CASE_MASK[i];
      }
    }
  }

  // Select the case based on the index and get the list of edges for this case
  triangleCase = triangleCases + index;
  edge = triangleCase->edges;

  // generate each triangle
  for (; edge[0] > -1; edge += 3)
  {
    for (i = 0; i < 3; i++) // insert triangle
    {
      // vertex exists, and need not be interpolated
      if (edge[i] >= 100)
      {
        vertexId = edge[i] - 100;
        this->Points->GetPoint(vertexId, x);
        if (locator->InsertUniquePoint(x, pts[i]))
        {
          outPd->CopyData(inPd, this->PointIds->GetId(vertexId), pts[i]);
        }
      }

      else // new vertex, interpolate
      {