Method ProcessBound

TheForceEngine/TFE_Polygon/clipper.cpp:928–1042

//------------------------------------------------------------------------------

TEdge* ClipperBase::ProcessBound(TEdge* E, bool NextIsForward)
{
  TEdge *Result = E;
  TEdge *Horz = 0;

  if (E->OutIdx == Skip)
  {
    //if edges still remain in the current bound beyond the skip edge then
    //create another LocMin and call ProcessBound once more
    if (NextIsForward)
    {
      while (E->Top.Y == E->Next->Bot.Y) E = E->Next;
      //don't include top horizontals when parsing a bound a second time,
      //they will be contained in the opposite bound ...
      while (E != Result && IsHorizontal(*E)) E = E->Prev;
    }
    else
    {
      while (E->Top.Y == E->Prev->Bot.Y) E = E->Prev;
      while (E != Result && IsHorizontal(*E)) E = E->Next;
    }

    if (E == Result)
    {
      if (NextIsForward) Result = E->Next;
      else Result = E->Prev;
    }
    else
    {
      //there are more edges in the bound beyond result starting with E
      if (NextIsForward)
        E = Result->Next;
      else
        E = Result->Prev;
      MinimaList::value_type locMin;
      locMin.Y = E->Bot.Y;
      locMin.LeftBound = 0;
      locMin.RightBound = E;
      E->WindDelta = 0;
      Result = ProcessBound(E, NextIsForward);
      m_MinimaList.push_back(locMin);
    }
    return Result;
  }

  TEdge *EStart;

  if (IsHorizontal(*E))
  {
    //We need to be careful with open paths because this may not be a
    //true local minima (ie E may be following a skip edge).
    //Also, consecutive horz. edges may start heading left before going right.
    if (NextIsForward) 
      EStart = E->Prev;
    else 
      EStart = E->Next;
    if (IsHorizontal(*EStart)) //ie an adjoining horizontal skip edge
      {