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1 | -- Created on: 1992-10-08 |
2 | -- Created by: Isabelle GRIGNON |
3 | -- Copyright (c) 1992-1999 Matra Datavision |
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4 | -- Copyright (c) 1999-2014 OPEN CASCADE SAS |
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5 | -- |
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6 | -- This file is part of Open CASCADE Technology software library. |
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7 | -- |
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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 |
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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. |
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13 | -- |
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14 | -- Alternatively, this file may be used under the terms of Open CASCADE |
15 | -- commercial license or contractual agreement. |
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16 | |
17 | package Adaptor2d |
18 | |
19 | ---Purpose: The Adaptor2d package is used to help defining |
20 | -- reusable geometric algorithms. i.e. that can be |
21 | -- used on curves and surfaces. |
22 | -- |
23 | -- It defines general services for objects : |
24 | -- |
25 | -- - the 2d curve. Curve2d |
26 | -- |
27 | -- The services are : |
28 | -- |
29 | -- - Usual services found in Geom or Geom2d : |
30 | -- |
31 | -- * parameter range, value and derivatives, etc... |
32 | -- |
33 | -- - Continuity breakout services : |
34 | -- |
35 | -- * Allows to divide a curve or a surfaces in |
36 | -- parts with a given derivation order. |
37 | -- |
38 | -- - Special geometries detection services : |
39 | -- |
40 | -- * Allows to test for special cases that can |
41 | -- be processed more easily : |
42 | -- - Conics, Quadrics, Bezier, BSpline ... |
43 | -- |
44 | -- And to get the correponding data form the |
45 | -- package gp or Geom. The special type |
46 | -- OtherCurve means that no special case has |
47 | -- been detected and the algorithm may use |
48 | -- only the evaluation methods (D0, D1, ...) |
49 | -- |
50 | -- |
51 | -- For each category Curve2d, Curve, Surface we |
52 | -- define three classes, we illustrate now the |
53 | -- principles with the Curve, the same applies to |
54 | -- Curve2d and Surface. |
55 | -- |
56 | -- The class Curve is the abstract root for all |
57 | -- Curves used by algorithms, it is handled by value |
58 | -- and provides as deferred methods the services |
59 | -- described above. |
60 | -- |
61 | -- Some services (breakout) requires to create new |
62 | -- curves, this leads to memory allocation |
63 | -- considerations (who create the curve, who deletes |
64 | -- it ?). To solve this problem elegantly the curve |
65 | -- will return a HCurve, the HCurve is a curve |
66 | -- handled by reference so it will be deallocated |
67 | -- automatically when it is not used. |
68 | -- |
69 | -- A third class GenHCurve is provided, this class is |
70 | -- generic and its utility is to provide automatic |
71 | -- generation of the HCurve class when you have |
72 | -- written the Curve class. |
73 | -- |
74 | -- |
75 | -- * Let us show an example (with 2d curves) : |
76 | -- |
77 | -- Imagine an algorithm to intersect curves, this |
78 | -- algorithms is written to process Curve2d from |
79 | -- Adaptor2d : |
80 | -- |
81 | -- A method may look like : |
82 | -- |
83 | -- Intersect(C1,C2 : Curve2d from Adaptor2d); |
84 | -- |
85 | -- Which will look like in C++ |
86 | -- |
87 | -- Intersect(const Adaptor2d_Curve2d& C1, |
88 | -- const Adaptor2d_Curve2d& C2) |
89 | -- { |
90 | -- // you can call any method |
91 | -- Standard_Real first1 = C1.FirstParameter(); |
92 | -- |
93 | -- // but avoid to copy in an Adaptor2d_Curve which |
94 | -- // is an Abstract class, use a reference or a pointer |
95 | -- |
96 | -- const Adaptor2d_Curve& C = C1; |
97 | -- const Adaptor2d_Curve *pC = &C1; |
98 | -- |
99 | -- // If you are interseted in Intervals you must |
100 | -- // store them in a HCurve to ensure they are kept |
101 | -- // in memory. Then a referrence may be used. |
102 | -- |
103 | -- Handle(Adaptor2d_HCurve) HCI = C1.Interval(1); |
104 | -- |
105 | -- const Adaptor2d_Curve& CI = HCI->Curve(); |
106 | -- pC = &(HCI->Curve()); |
107 | -- |
108 | -- |
109 | -- * The Adaptor2d provides also Generic classes |
110 | -- implementing algorithmic curves and surfaces. |
111 | -- |
112 | -- - IsoCurve : Isoparametric curve on a surface. |
113 | -- - CurveOnSurface : 2D curve in the parametric |
114 | -- space of a surface. |
115 | -- |
116 | -- |
117 | -- - OffsetCurve2d : 2d offset curve |
118 | -- - ProjectedCurve : 3d curve projected on a plane |
119 | -- - SurfaceOfLinearExtrusion |
120 | -- - SurfaceOfRevolution |
121 | -- |
122 | -- They are instantiated with HCurve, HSurface, HCurved2d |
123 | |
124 | uses |
125 | Standard, |
126 | MMgt, |
127 | TColStd, |
128 | GeomAbs, |
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129 | TColgp, |
130 | gp, |
131 | Geom2d, |
132 | math |
133 | |
134 | is |
135 | |
136 | deferred class Curve2d; |
137 | ---Purpose: Root of the 2d curve. |
138 | |
139 | pointer Curve2dPtr to Curve2d from Adaptor2d; |
140 | |
141 | deferred class HCurve2d; |
142 | ---Purpose: deferred class for the 2d curves manipulated with |
143 | -- Handle. |
144 | |
145 | generic class GenHCurve2d; |
146 | ---Purpose: Generic class used to create a curve inheriting |
147 | -- from HCurve2d. |
148 | |
149 | |
150 | |
151 | -- |
152 | -- The following classes are used to define an abstract |
153 | -- simplified "topology" for surfaces. This is used by |
154 | -- algorithm as mass properties or surface intersections. |
155 | -- |
156 | |
157 | |
158 | class Line2d; |
159 | |
160 | class HLine2d instantiates GenHCurve2d(Line2d from Adaptor2d); |
161 | ---Purpose: Use by the TopolTool to trim a surface. |
162 | |
163 | -- |
164 | -- The following classes provides algorithmic curves and |
165 | -- surface, they are inheriting from Curve and Surface and the |
166 | -- correponding HCurve and HSurface is instantiated. |
167 | -- |
168 | -- |
169 | |
170 | |
171 | |
172 | end Adaptor2d; |