Method ProcessEdgesAtTopOfScanbeam

renderers/agg/src/clipper.cpp:1846–1897

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

void Clipper::ProcessEdgesAtTopOfScanbeam(const long64 topY)
{
  TEdge* e = m_ActiveEdges;
  while( e )
  {
    //1. process maxima, treating them as if they're 'bent' horizontal edges,
    //   but exclude maxima with horizontal edges. nb: e can't be a horizontal.
    if( IsMaxima(e, topY) && GetMaximaPair(e)->dx != horizontal )
    {
      //'e' might be removed from AEL, as may any following edges so ...
      TEdge* ePrior = e->prevInAEL;
      DoMaxima(e, topY);
      if( !ePrior ) e = m_ActiveEdges;
      else e = ePrior->nextInAEL;
    }
    else
    {
      //2. promote horizontal edges, otherwise update xcurr and ycurr ...
      if(  IsIntermediate(e, topY) && e->nextInLML->dx == horizontal )
      {
        if (e->outIdx >= 0)
        {
          AddPolyPt(e, IntPoint(e->xtop, e->ytop));
          AddHorzJoin(e->nextInLML, e->outIdx);
        }
        UpdateEdgeIntoAEL(e);
        AddEdgeToSEL(e);
      } else
      {
        //this just simplifies horizontal processing ...
        e->xcurr = TopX( *e, topY );
        e->ycurr = topY;
      }
      e = e->nextInAEL;
    }
  }

  //3. Process horizontals at the top of the scanbeam ...
  ProcessHorizontals();

  //4. Promote intermediate vertices ...
  e = m_ActiveEdges;
  while( e )
  {
    if( IsIntermediate( e, topY ) )
    {
      if( e->outIdx >= 0 ) AddPolyPt(e, IntPoint(e->xtop,e->ytop));
      UpdateEdgeIntoAEL(e);
    }
    e = e->nextInAEL;
  }
}
//------------------------------------------------------------------------------

PolyPt* FixupOutPolygon(PolyPt *p)