OCCT

// Created on: 1994-08-03
// Created by: Christophe MARION
// Copyright (c) 1994-1999 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.

#ifndef _HLRBRep_Algo_HeaderFile
#define _HLRBRep_Algo_HeaderFile

#include <Standard.hxx>

#include <HLRBRep_InternalAlgo.hxx>
#include <Standard_Integer.hxx>
class TopoDS_Shape;
class Standard_Transient;

//! Inherited from InternalAlgo to provide methods with Shape from TopoDS.
//! A framework to compute a shape as seen in a projection plane. This is done by
//! calculating the visible and the hidden parts of the shape.
//! HLRBRep_Algo works with three types of entity:
//! -   shapes to be visualized
//! -   edges in these shapes (these edges are
//! the basic entities which will be visualized or hidden), and
//! -   faces in these shapes which hide the edges.
//! HLRBRep_Algo is based on the principle of comparing each edge of the shape to be
//! visualized with each of its faces, and calculating the visible and the hidden parts of each
//! edge. For a given projection, HLRBRep_Algo calculates a set of lines characteristic of the
//! object being represented. It is also used in conjunction with the
//! HLRBRep_HLRToShape extraction utilities, which reconstruct a new, simplified shape
//! from a selection of calculation results. This new shape is made up of edges, which
//! represent the shape visualized in the projection.
//! HLRBRep_Algo takes the shape itself into account whereas HLRBRep_PolyAlgo
//! works with a polyhedral simplification of the shape. When you use HLRBRep_Algo, you
//! obtain an exact result, whereas, when you use HLRBRep_PolyAlgo, you reduce
//! computation time but obtain polygonal segments. In the case of complicated
//! shapes, HLRBRep_Algo may be time-consuming.
//! An HLRBRep_Algo object provides a framework for:
//! -   defining the point of view
//! -   identifying the shape or shapes to be visualized
//! -   calculating the outlines
//! -   calculating the visible and hidden lines of the shape.
//! Warning
//! -   Superimposed lines are not eliminated by this algorithm.
//! -   There must be no unfinished objects inside the shape you wish to visualize.
//! -   Points are not treated.
//! -   Note that this is not the sort of algorithm used in generating shading, which
//! calculates the visible and hidden parts of each face in a shape to be visualized by
//! comparing each face in the shape with every other face in the same shape.
class HLRBRep_Algo : public HLRBRep_InternalAlgo
{

public:
  //! Constructs an empty framework for the
  //! calculation of visible and hidden lines of a shape in a projection.
  //! Use the function:
  //! -   Projector to define the point of view
  //! -   Add to select the shape or shapes to be visualized
  //! -   Update to compute the outlines of the shape, and
  //! -   Hide to compute the visible and hidden lines of the shape.
  Standard_EXPORT HLRBRep_Algo();

  Standard_EXPORT HLRBRep_Algo(const occ::handle<HLRBRep_Algo>& A);

  //! add the Shape <S>.
  Standard_EXPORT void Add(const TopoDS_Shape&                    S,
                           const occ::handle<Standard_Transient>& SData,
                           const int                              nbIso = 0);

  //! Adds the shape S to this framework, and
  //! specifies the number of isoparameters nbiso desired in visualizing S.
  //! You may add as many shapes as you wish. Use the function Add once for each shape.
  Standard_EXPORT void Add(const TopoDS_Shape& S, const int nbIso = 0);

  //! return the index of the Shape <S> and
  //! return 0 if the Shape <S> is not found.
  Standard_EXPORT int Index(const TopoDS_Shape& S);

  //! nullify all the results of OutLiner from HLRTopoBRep.
  Standard_EXPORT void OutLinedShapeNullify();

  DEFINE_STANDARD_RTTIEXT(HLRBRep_Algo, HLRBRep_InternalAlgo)
};

#endif // _HLRBRep_Algo_HeaderFile