Method AddPath

TheForceEngine/TFE_Polygon/clipper.cpp:1045–1221

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

bool ClipperBase::AddPath(const Path &pg, PolyType PolyTyp, bool Closed)
{
#ifdef use_lines
  if (!Closed && PolyTyp == ptClip)
    throw clipperException("AddPath: Open paths must be subject.");
#else
  if (!Closed)
    throw clipperException("AddPath: Open paths have been disabled.");
#endif

  int highI = (int)pg.size() -1;
  if (Closed) while (highI > 0 && (pg[highI] == pg[0])) --highI;
  while (highI > 0 && (pg[highI] == pg[highI -1])) --highI;
  if ((Closed && highI < 2) || (!Closed && highI < 1)) return false;

  //create a new edge array ...
  TEdge *edges = new TEdge [highI +1];

  bool IsFlat = true;
  //1. Basic (first) edge initialization ...
  try
  {
    edges[1].Curr = pg[1];
    RangeTest(pg[0], m_UseFullRange);
    RangeTest(pg[highI], m_UseFullRange);
    InitEdge(&edges[0], &edges[1], &edges[highI], pg[0]);
    InitEdge(&edges[highI], &edges[0], &edges[highI-1], pg[highI]);
    for (int i = highI - 1; i >= 1; --i)
    {
      RangeTest(pg[i], m_UseFullRange);
      InitEdge(&edges[i], &edges[i+1], &edges[i-1], pg[i]);
    }
  }
  catch(...)
  {
    delete [] edges;
    throw; //range test fails
  }
  TEdge *eStart = &edges[0];

  //2. Remove duplicate vertices, and (when closed) collinear edges ...
  TEdge *E = eStart, *eLoopStop = eStart;
  for (;;)
  {
    //nb: allows matching start and end points when not Closed ...
    if (E->Curr == E->Next->Curr && (Closed || E->Next != eStart))
    {
      if (E == E->Next) break;
      if (E == eStart) eStart = E->Next;
      E = RemoveEdge(E);
      eLoopStop = E;
      continue;
    }
    if (E->Prev == E->Next) 
      break; //only two vertices
    else if (Closed &&
      SlopesEqual(E->Prev->Curr, E->Curr, E->Next->Curr, m_UseFullRange) && 
      (!m_PreserveCollinear ||