occt/src/StdPrs/StdPrs_ToolShadedShape.cxx

// Created on: 1993-10-27
// Created by: Jean-LOuis FRENKEL
// Copyright (c) 1993-1999 Matra Datavision
// Copyright (c) 1999-2014 OPEN CASCADE SAS
//
// This file is part of Open CASCADE Technology software library.
//
// This library is free software; you can redistribute it and/or modify it under
// the terms of the GNU Lesser General Public License version 2.1 as published
// by the Free Software Foundation, with special exception defined in the file
// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
// distribution for complete text of the license and disclaimer of any warranty.
//
// Alternatively, this file may be used under the terms of Open CASCADE
// commercial license or contractual agreement.

#include <StdPrs_ToolShadedShape.ixx>

#include <BRep_Tool.hxx>
#include <BRepAdaptor_Surface.hxx>
#include <GeomAbs_SurfaceType.hxx>
#include <GeomLib.hxx>
#include <gp_Vec.hxx>
#include <Poly_Connect.hxx>
#include <Poly_Triangulation.hxx>
#include <Precision.hxx>
#include <TColgp_HArray1OfPnt.hxx>
#include <TColgp_Array1OfPnt.hxx>
#include <TColgp_Array1OfPnt2d.hxx>
#include <TopAbs_Orientation.hxx>
#include <TopLoc_Location.hxx>
#include <TShort_HArray1OfShortReal.hxx>
#include <TShort_Array1OfShortReal.hxx>

namespace
{
  //=======================================================================
  //function : isTriangulated
  //purpose  : Returns true if all faces within shape are triangulated.
  //           Same as BRepTools::Triangulation() but without extra checks.
  //=======================================================================
  static Standard_Boolean isTriangulated (const TopoDS_Shape& theShape)
  {
    TopLoc_Location aLocDummy;
    for (TopExp_Explorer aFaceIter (theShape, TopAbs_FACE); aFaceIter.More(); aFaceIter.Next())
    {
      const TopoDS_Face&                aFace = TopoDS::Face (aFaceIter.Current());
      const Handle(Poly_Triangulation)& aTri  = BRep_Tool::Triangulation (aFace, aLocDummy);
      if (aTri.IsNull())
      {
        return Standard_False;
      }
    }
    return Standard_True;
  }
}

//=======================================================================
//function : IsClosed
//purpose  :
//=======================================================================
Standard_Boolean StdPrs_ToolShadedShape::IsClosed (const TopoDS_Shape& theShape)
{
  if (theShape.IsNull())
  {
    return Standard_True;
  }

  switch (theShape.ShapeType())
  {
    case TopAbs_COMPOUND:
    case TopAbs_COMPSOLID:
    default:
    {
      // check that compound consists of closed solids
      for (TopoDS_Iterator anIter (theShape); anIter.More(); anIter.Next())
      {
        const TopoDS_Shape& aShape = anIter.Value();
        if (!IsClosed (aShape))
        {
          return Standard_False;
        }
      }
      return Standard_True;
    }
    case TopAbs_SOLID:
    {
      for (TopoDS_Iterator anIter (theShape); anIter.More(); anIter.Next())
      {
        const TopoDS_Shape& aShape = anIter.Value();
        if (aShape.IsNull())
        {
          continue;
        }

        if (aShape.ShapeType() == TopAbs_SHELL
        && !aShape.Closed())
        {
          return Standard_False;
        }
        else if (aShape.ShapeType() == TopAbs_FACE)
        {
          // invalid solid
          return Standard_False;
        }
        else if (!isTriangulated (aShape))
        {
          // mesh contains holes
          return Standard_False;
        }
      }
      return Standard_True;
    }
    case TopAbs_SHELL:
    case TopAbs_FACE:
    {
      // free faces / shell are not allowed
      return Standard_False;
    }
    case TopAbs_WIRE:
    case TopAbs_EDGE:
    case TopAbs_VERTEX:
    {
      // ignore
      return Standard_True;
    }
  }
}

//=======================================================================
//function : Triangulation
//purpose  :
//=======================================================================
Handle(Poly_Triangulation) StdPrs_ToolShadedShape::Triangulation (const TopoDS_Face& theFace,
                                                                  TopLoc_Location&   theLoc)
{
  return BRep_Tool::Triangulation (theFace, theLoc);
}

//=======================================================================
//function : Normal
//purpose  :
//=======================================================================
void StdPrs_ToolShadedShape::Normal (const TopoDS_Face&  theFace,
                                     Poly_Connect&       thePolyConnect,
                                     TColgp_Array1OfDir& theNormals)
{
  const Handle(Poly_Triangulation)& aPolyTri = thePolyConnect.Triangulation();
  const TColgp_Array1OfPnt&         aNodes   = aPolyTri->Nodes();
  if (aPolyTri->HasNormals())
  {
    // normals pre-computed in triangulation structure
    const TShort_Array1OfShortReal& aNormals = aPolyTri->Normals();
    const Standard_ShortReal*       aNormArr = &(aNormals.Value (aNormals.Lower()));
    for (Standard_Integer aNodeIter = aNodes.Lower(); aNodeIter <= aNodes.Upper(); ++aNodeIter)
    {
      const Standard_Integer anId = 3 * (aNodeIter - aNodes.Lower());
      const gp_Dir aNorm (aNormArr[anId + 0],
                          aNormArr[anId + 1],
                          aNormArr[anId + 2]);
      theNormals (aNodeIter) = aNorm;
    }

    if (theFace.Orientation() == TopAbs_REVERSED)
    {
      for (Standard_Integer aNodeIter = aNodes.Lower(); aNodeIter <= aNodes.Upper(); ++aNodeIter)
      {
        theNormals.ChangeValue (aNodeIter).Reverse();
      }
    }
    return;
  }

  // take in face the surface location
  const TopoDS_Face      aZeroFace = TopoDS::Face (theFace.Located (TopLoc_Location()));
  Handle(Geom_Surface)   aSurf     = BRep_Tool::Surface (aZeroFace);
  const Standard_Real    aTol      = Precision::Confusion();
  Handle(TShort_HArray1OfShortReal) aNormals = new TShort_HArray1OfShortReal (1, aPolyTri->NbNodes() * 3);
  const Poly_Array1OfTriangle& aTriangles = aPolyTri->Triangles();
  const TColgp_Array1OfPnt2d*  aNodesUV   = aPolyTri->HasUVNodes() && !aSurf.IsNull()
                                          ? &aPolyTri->UVNodes()
                                          : NULL;
  Standard_Integer aTri[3];
  for (Standard_Integer aNodeIter = aNodes.Lower(); aNodeIter <= aNodes.Upper(); ++aNodeIter)
  {
    // try to retrieve normal from real surface first, when UV coordinates are available
    if (aNodesUV == NULL
     || GeomLib::NormEstim (aSurf, aNodesUV->Value (aNodeIter), aTol, theNormals (aNodeIter)) > 1)
    {
      // compute flat normals
      gp_XYZ eqPlan (0.0, 0.0, 0.0);
      for (thePolyConnect.Initialize (aNodeIter); thePolyConnect.More(); thePolyConnect.Next())
      {
        aTriangles (thePolyConnect.Value()).Get (aTri[0], aTri[1], aTri[2]);
        const gp_XYZ v1 (aNodes (aTri[1]).Coord() - aNodes (aTri[0]).Coord());
        const gp_XYZ v2 (aNodes (aTri[2]).Coord() - aNodes (aTri[1]).Coord());
        const gp_XYZ vv = v1 ^ v2;
        const Standard_Real aMod = vv.Modulus();
        if (aMod >= aTol)
        {
          eqPlan += vv / aMod;
        }
      }
      const Standard_Real aModMax = eqPlan.Modulus();
      theNormals (aNodeIter) = (aModMax > aTol) ? gp_Dir (eqPlan) : gp::DZ();
    }

    const Standard_Integer anId = (aNodeIter - aNodes.Lower()) * 3;
    aNormals->SetValue (anId + 1, (Standard_ShortReal )theNormals (aNodeIter).X());
    aNormals->SetValue (anId + 2, (Standard_ShortReal )theNormals (aNodeIter).Y());
    aNormals->SetValue (anId + 3, (Standard_ShortReal )theNormals (aNodeIter).Z());
  }
  aPolyTri->SetNormals (aNormals);

  if (theFace.Orientation() == TopAbs_REVERSED)
  {
    for (Standard_Integer aNodeIter = aNodes.Lower(); aNodeIter <= aNodes.Upper(); ++aNodeIter)
    {
      theNormals.ChangeValue (aNodeIter).Reverse();
    }
  }
}