Function CleanPolygon

TheForceEngine/TFE_Polygon/clipper.cpp:4390–4447

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

void CleanPolygon(const Path& in_poly, Path& out_poly, double distance)
{
  //distance = proximity in units/pixels below which vertices
  //will be stripped. Default ~= sqrt(2).
  
  size_t size = in_poly.size();
  
  if (size == 0) 
  {
    out_poly.clear();
    return;
  }

  OutPt* outPts = new OutPt[size];
  for (size_t i = 0; i < size; ++i)
  {
    outPts[i].Pt = in_poly[i];
    outPts[i].Next = &outPts[(i + 1) % size];
    outPts[i].Next->Prev = &outPts[i];
    outPts[i].Idx = 0;
  }

  double distSqrd = distance * distance;
  OutPt* op = &outPts[0];
  while (op->Idx == 0 && op->Next != op->Prev) 
  {
    if (PointsAreClose(op->Pt, op->Prev->Pt, distSqrd))
    {
      op = ExcludeOp(op);
      size--;
    } 
    else if (PointsAreClose(op->Prev->Pt, op->Next->Pt, distSqrd))
    {
      ExcludeOp(op->Next);
      op = ExcludeOp(op);
      size -= 2;
    }
    else if (SlopesNearCollinear(op->Prev->Pt, op->Pt, op->Next->Pt, distSqrd))
    {
      op = ExcludeOp(op);
      size--;
    }
    else
    {
      op->Idx = 1;
      op = op->Next;
    }
  }

  if (size < 3) size = 0;
  out_poly.resize(size);
  for (size_t i = 0; i < size; ++i)
  {
    out_poly[i] = op->Pt;
    op = op->Next;
  }
  delete [] outPts;
}