1 // Created on: 1994-08-03
2 // Created by: Christophe MARION
3 // Copyright (c) 1994-1999 Matra Datavision
4 // Copyright (c) 1999-2014 OPEN CASCADE SAS
6 // This file is part of Open CASCADE Technology software library.
8 // This library is free software; you can redistribute it and/or modify it under
9 // the terms of the GNU Lesser General Public License version 2.1 as published
10 // by the Free Software Foundation, with special exception defined in the file
11 // OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
12 // distribution for complete text of the license and disclaimer of any warranty.
14 // Alternatively, this file may be used under the terms of Open CASCADE
15 // commercial license or contractual agreement.
17 #ifndef _HLRBRep_Algo_HeaderFile
18 #define _HLRBRep_Algo_HeaderFile
20 #include <Standard.hxx>
21 #include <Standard_Type.hxx>
23 #include <HLRBRep_InternalAlgo.hxx>
24 #include <Standard_Integer.hxx>
30 DEFINE_STANDARD_HANDLE(HLRBRep_Algo, HLRBRep_InternalAlgo)
32 //! Inherited from InternalAlgo to provide methods with Shape from TopoDS.
33 //! A framework to compute a shape as seen in a projection plane. This is done by
34 //! calculating the visible and the hidden parts of the shape.
35 //! HLRBRep_Algo works with three types of entity:
36 //! - shapes to be visualized
37 //! - edges in these shapes (these edges are
38 //! the basic entities which will be visualized or hidden), and
39 //! - faces in these shapes which hide the edges.
40 //! HLRBRep_Algo is based on the principle of comparing each edge of the shape to be
41 //! visualized with each of its faces, and calculating the visible and the hidden parts of each edge.
42 //! For a given projection, HLRBRep_Algo calculates a set of lines characteristic of the
43 //! object being represented. It is also used in conjunction with the
44 //! HLRBRep_HLRToShape extraction utilities, which reconstruct a new, simplified shape
45 //! from a selection of calculation results. This new shape is made up of edges, which
46 //! represent the shape visualized in the projection.
47 //! HLRBRep_Algo takes the shape itself into account whereas HLRBRep_PolyAlgo
48 //! works with a polyhedral simplification of the shape. When you use HLRBRep_Algo, you
49 //! obtain an exact result, whereas, when you use HLRBRep_PolyAlgo, you reduce
50 //! computation time but obtain polygonal segments. In the case of complicated
51 //! shapes, HLRBRep_Algo may be time-consuming.
52 //! An HLRBRep_Algo object provides a framework for:
53 //! - defining the point of view
54 //! - identifying the shape or shapes to be visualized
55 //! - calculating the outlines
56 //! - calculating the visible and hidden lines of the shape.
58 //! - Superimposed lines are not eliminated by this algorithm.
59 //! - There must be no unfinished objects inside the shape you wish to visualize.
60 //! - Points are not treated.
61 //! - Note that this is not the sort of algorithm used in generating shading, which
62 //! calculates the visible and hidden parts of each face in a shape to be visualized by
63 //! comparing each face in the shape with every other face in the same shape.
64 class HLRBRep_Algo : public HLRBRep_InternalAlgo
70 //! Constructs an empty framework for the
71 //! calculation of visible and hidden lines of a shape in a projection.
73 //! - Projector to define the point of view
74 //! - Add to select the shape or shapes to be visualized
75 //! - Update to compute the outlines of the shape, and
76 //! - Hide to compute the visible and hidden lines of the shape.
77 Standard_EXPORT HLRBRep_Algo();
79 Standard_EXPORT HLRBRep_Algo(const Handle(HLRBRep_Algo)& A);
81 //! add the Shape <S>.
82 Standard_EXPORT void Add (const TopoDS_Shape& S, const Handle(MMgt_TShared)& SData, const Standard_Integer nbIso = 0);
84 //! Adds the shape S to this framework, and
85 //! specifies the number of isoparameters nbiso desired in visualizing S.
86 //! You may add as many shapes as you wish. Use the function Add once for each shape.
87 Standard_EXPORT void Add (const TopoDS_Shape& S, const Standard_Integer nbIso = 0);
89 //! return the index of the Shape <S> and
90 //! return 0 if the Shape <S> is not found.
91 Standard_EXPORT Standard_Integer Index (const TopoDS_Shape& S);
93 //! nullify all the results of OutLiner from HLRTopoBRep.
94 Standard_EXPORT void OutLinedShapeNullify();
99 DEFINE_STANDARD_RTTIEXT(HLRBRep_Algo,HLRBRep_InternalAlgo)
119 #endif // _HLRBRep_Algo_HeaderFile