b311480e |
1 | -- Created on: 1993-03-24 |
2 | -- Created by: Philippe DAUTRY |
3 | -- Copyright (c) 1993-1999 Matra Datavision |
4 | -- Copyright (c) 1999-2012 OPEN CASCADE SAS |
5 | -- |
6 | -- The content of this file is subject to the Open CASCADE Technology Public |
7 | -- License Version 6.5 (the "License"). You may not use the content of this file |
8 | -- except in compliance with the License. Please obtain a copy of the License |
9 | -- at http://www.opencascade.org and read it completely before using this file. |
10 | -- |
11 | -- The Initial Developer of the Original Code is Open CASCADE S.A.S., having its |
12 | -- main offices at: 1, place des Freres Montgolfier, 78280 Guyancourt, France. |
13 | -- |
14 | -- The Original Code and all software distributed under the License is |
15 | -- distributed on an "AS IS" basis, without warranty of any kind, and the |
16 | -- Initial Developer hereby disclaims all such warranties, including without |
17 | -- limitation, any warranties of merchantability, fitness for a particular |
18 | -- purpose or non-infringement. Please see the License for the specific terms |
19 | -- and conditions governing the rights and limitations under the License. |
20 | |
7fd59977 |
21 | |
7fd59977 |
22 | |
23 | |
24 | class OffsetCurve from Geom2d inherits Curve from Geom2d |
25 | |
26 | |
27 | --- Purpose : |
28 | -- This class implements the basis services for the creation, |
29 | -- edition, modification and evaluation of planar offset curve. |
30 | -- The offset curve is obtained by offsetting by distance along |
31 | -- the normal to a basis curve defined in 2D space. |
32 | -- The offset curve in this package can be a self intersecting |
33 | -- curve even if the basis curve does not self-intersect. |
34 | -- The self intersecting portions are not deleted at the |
35 | -- construction time. |
36 | -- An offset curve is a curve at constant distance (Offset) from a |
37 | -- basis curve and the offset curve takes its parametrization from |
38 | -- the basis curve. The Offset curve is in the direction of the |
39 | -- normal to the basis curve N. |
40 | -- The distance offset may be positive or negative to indicate the |
41 | -- preferred side of the curve : |
42 | -- . distance offset >0 => the curve is in the direction of N |
43 | -- . distance offset >0 => the curve is in the direction of - N |
44 | -- On the Offset curve : |
45 | -- Value(u) = BasisCurve.Value(U) + (Offset * (T ^ Z)) / ||T ^ Z|| |
46 | -- where T is the tangent vector to the basis curve and Z the |
47 | -- direction of the normal vector to the plane of the curve, |
48 | -- N = T ^ Z defines the offset direction and should not have |
49 | -- null length. |
50 | -- |
51 | -- Warnings : |
52 | -- In this package we suppose that the continuity of the offset |
53 | -- curve is one degree less than the continuity of the |
54 | -- basis curve and we don't check that at any point ||T^Z|| != 0.0 |
55 | -- |
56 | -- So to evaluate the curve it is better to check that the offset |
57 | -- curve is well defined at any point because an exception could |
58 | -- be raised. The check is not done in this package at the creation |
59 | -- of the offset curve because the control needs the use of an |
60 | -- algorithm which cannot be implemented in this package. |
61 | -- The OffsetCurve is closed if the first point and the last point |
62 | -- are the same (The distance between these two points is lower or |
63 | -- equal to the Resolution sea package gp) . The OffsetCurve can be |
64 | -- closed even if the basis curve is not closed. |
65 | |
66 | uses Dir2d from gp, |
67 | Pnt2d from gp, |
68 | Trsf2d from gp, |
69 | Vec2d from gp, |
70 | Curve from Geom2d, |
71 | Geometry from Geom2d, |
72 | Shape from GeomAbs |
73 | |
74 | |
75 | raises ConstructionError from Standard, |
76 | RangeError from Standard, |
77 | NoSuchObject from Standard, |
78 | UndefinedDerivative from Geom2d, |
79 | UndefinedValue from Geom2d, |
80 | NotImplemented from Standard |
81 | |
82 | |
83 | |
84 | is |
85 | |
86 | |
87 | Create (C : Curve from Geom2d; Offset : Real) returns mutable OffsetCurve |
88 | --- Purpose : Constructs a curve offset from the basis curve C, |
89 | -- where Offset is the distance between the offset |
90 | -- curve and the basis curve at any point. |
91 | -- A point on the offset curve is built by measuring the |
92 | -- offset value along a normal vector at a point on C. |
93 | -- This normal vector is obtained by rotating the |
94 | -- vector tangential to C at 90 degrees in the |
95 | -- anti-trigonometric sense. The side of C on which |
96 | -- the offset value is measured is indicated by this |
97 | -- normal vector if Offset is positive, or in the inverse |
98 | -- sense if Offset is negative. |
99 | -- Warnings : |
100 | -- In this package the entities are not shared. The OffsetCurve is |
101 | -- built with a copy of the curve C. So when C is modified the |
102 | -- OffsetCurve is not modified |
103 | -- Warning! ConstructionError raised if the basis curve C is not at least C1. |
104 | -- No check is done to know if ||V^Z|| != 0.0 at any point. |
105 | raises ConstructionError; |
106 | |
107 | |
108 | |
109 | Reverse (me : mutable); |
110 | --- Purpose : Changes the direction of parametrization of <me>. |
111 | -- As a result: |
112 | -- - the basis curve is reversed, |
113 | -- - the start point of the initial curve becomes the end |
114 | -- point of the reversed curve, |
115 | -- - the end point of the initial curve becomes the start |
116 | -- point of the reversed curve, and |
117 | -- - the first and last parameters are recomputed. |
118 | |
119 | |
120 | ReversedParameter(me; U : Real) returns Real; |
121 | ---Purpose: Computes the parameter on the reversed curve for |
122 | -- the point of parameter U on this offset curve. |
123 | |
124 | |
125 | SetBasisCurve (me : mutable; C : Curve from Geom2d) |
126 | raises ConstructionError; |
127 | --- Purpose : Changes this offset curve by assigning C as the |
128 | -- basis curve from which it is built. |
129 | -- Exceptions |
130 | -- Standard_ConstructionError if the curve C is not at least "C1" continuous. |
131 | |
132 | SetOffsetValue (me : mutable; D : Real); |
133 | --- Purpose : Changes this offset curve by assigning D as the offset value. |
134 | |
135 | BasisCurve (me) returns Curve from Geom2d; |
136 | --- Purpose : Returns the basis curve of this offset curve. The basis curve can be an offset curve. |
137 | |
138 | |
139 | |
140 | Continuity (me) returns Shape from GeomAbs; |
141 | --- Purpose : |
142 | -- Continuity of the Offset curve : |
143 | -- C0 : only geometric continuity, |
144 | -- C1 : continuity of the first derivative all along the Curve, |
145 | -- C2 : continuity of the second derivative all along the Curve, |
146 | -- C3 : continuity of the third derivative all along the Curve, |
147 | -- G1 : tangency continuity all along the Curve, |
148 | -- G2 : curvature continuity all along the Curve, |
149 | -- CN : the order of continuity is infinite. |
150 | -- Warnings : |
151 | -- Returns the continuity of the basis curve - 1. |
152 | -- The offset curve must have a unique normal direction defined |
153 | -- at any point. |
154 | |
155 | |
156 | |
157 | |
158 | |
159 | --- Purpose : Value and derivatives |
160 | -- |
161 | -- Warnings : |
162 | -- The exception UndefinedValue or UndefinedDerivative is |
163 | -- raised if it is not possible to compute a unique offset |
164 | -- direction. |
165 | -- If T is the first derivative with not null length and |
166 | -- Z the direction normal to the plane of the curve, the |
167 | -- relation ||T(U) ^ Z|| != 0 must be satisfied to evaluate |
168 | -- the offset curve. |
169 | -- No check is done at the creation time and we suppose |
170 | -- in this package that the offset curve is well defined. |
171 | |
172 | |
173 | D0 (me; U : Real; P : out Pnt2d) |
174 | raises UndefinedValue; |
175 | ---Purpose: Warning! this should not be called |
176 | -- if the basis curve is not at least C1. Nevertheless |
177 | -- if used on portion where the curve is C1, it is OK |
178 | |
179 | |
180 | |
181 | D1 (me; U : Real; P : out Pnt2d; V1 : out Vec2d) |
182 | raises UndefinedDerivative; |
183 | ---Purpose: Warning! this should not be called |
184 | -- if the continuity of the basis curve is not C2. |
185 | -- Nevertheless, it's OK to use it on portion |
186 | -- where the curve is C2 |
187 | |
188 | |
189 | |
190 | D2 (me; U : Real; P : out Pnt2d; V1, V2 : out Vec2d) |
191 | raises UndefinedDerivative; |
192 | ---Purpose: Warning! This should not be called |
193 | -- if the continuity of the basis curve is not C3. |
194 | -- Nevertheless, it's OK to use it on portion |
195 | -- where the curve is C3 |
196 | |
197 | D3 (me; U : Real; P : out Pnt2d; V1, V2, V3 : out Vec2d) |
198 | raises UndefinedDerivative; |
199 | |
200 | ---Purpose: Warning! This should not be called |
201 | -- if the continuity of the basis curve is not C4. |
202 | -- Nevertheless, it's OK to use it on portion |
203 | -- where the curve is C4 |
204 | |
205 | DN (me; U : Real; N : Integer) returns Vec2d |
206 | --- Purpose : The returned vector gives the value of the derivative |
207 | -- for the order of derivation N. |
208 | -- Warning! this should not be called |
209 | -- raises UndefunedDerivative if the continuity of the basis curve is not CN+1. |
210 | -- Nevertheless, it's OK to use it on portion |
211 | -- where the curve is CN+1 |
212 | -- raises RangeError if N < 1. |
213 | -- raises NotImplemented if N > 3. |
214 | |
215 | raises UndefinedDerivative, |
216 | |
217 | RangeError, |
218 | NotImplemented; |
219 | |
220 | |
221 | |
222 | --- Purpose : The following functions compute the value and derivatives |
223 | -- on the offset curve and returns the derivatives on the |
224 | -- basis curve too. |
225 | -- The computation of the value and derivatives on the basis |
226 | -- curve are used to evaluate the offset curve |
227 | -- Warnings : |
228 | -- The exception UndefinedValue or UndefinedDerivative is |
229 | -- raised if it is not possible to compute a unique offset direction. |
230 | |
231 | |
232 | Value (me; U : Real; P, Pbasis : out Pnt2d; V1basis : out Vec2d) |
233 | raises UndefinedValue; |
234 | |
235 | ---Purpose: Warning! this should not be called |
236 | -- if the basis curve is not at least C1. Nevertheless |
237 | -- if used on portion where the curve is C1, it is OK |
238 | |
239 | |
240 | D1 (me; U : Real; P, Pbasis : out Pnt2d; |
241 | V1, V1basis, V2basis : out Vec2d) |
242 | raises UndefinedDerivative; |
243 | |
244 | ---Purpose: Warning! this should not be called |
245 | -- if the continuity of the basis curve is not C1. |
246 | -- Nevertheless, it's OK to use it on portion |
247 | -- where the curve is C1 |
248 | |
249 | D2 (me; U : Real; P, Pbasis : out Pnt2d; V1, V2, V1basis, V2basis, |
250 | V3basis : out Vec2d) |
251 | raises UndefinedDerivative; |
252 | |
253 | ---Purpose: Warning! this should not be called |
254 | -- if the continuity of the basis curve is not C3. |
255 | -- Nevertheless, it's OK to use it on portion |
256 | -- where the curve is C3 |
257 | |
258 | FirstParameter (me) returns Real; |
259 | |
260 | LastParameter (me) returns Real; |
261 | ---Purpose: Returns the value of the first or last parameter of this |
262 | -- offset curve. The first parameter corresponds to the |
263 | -- start point of the curve. The last parameter |
264 | -- corresponds to the end point. |
265 | -- Note: the first and last parameters of this offset curve |
266 | -- are also the ones of its basis curve. |
267 | |
268 | Offset (me) returns Real; |
269 | ---Purpose: Returns the offset value of this offset curve. |
270 | |
271 | IsClosed (me) returns Boolean; |
272 | --- Purpose : |
273 | -- Returns True if the distance between the start point |
274 | -- and the end point of the curve is lower or equal to |
275 | -- Resolution from package gp. |
276 | |
277 | |
278 | IsCN (me; N : Integer) returns Boolean |
279 | --- Purpose : Is the order of continuity of the curve N ? |
280 | -- Warnings : |
281 | -- This method answer True if the continuity of the basis curve |
282 | -- is N + 1. We suppose in this class that a normal direction |
283 | -- to the basis curve (used to compute the offset curve) is |
284 | -- defined at any point on the basis curve. |
285 | raises RangeError; |
286 | --- Purpose : Raised if N < 0. |
287 | |
288 | |
289 | IsPeriodic (me) returns Boolean; |
290 | --- Purpose : Is the parametrization of a curve is periodic ? |
291 | -- If the basis curve is a circle or an ellipse the corresponding |
292 | -- OffsetCurve is periodic. If the basis curve can't be periodic |
293 | -- (for example BezierCurve) the OffsetCurve can't be periodic. |
294 | |
295 | |
296 | Period (me) returns Real from Standard |
297 | ---Purpose: Returns the period of this offset curve, i.e. the period |
298 | -- of the basis curve of this offset curve. |
299 | -- Exceptions |
300 | -- Standard_NoSuchObject if the basis curve is not periodic. |
301 | raises NoSuchObject from Standard |
302 | is redefined; |
303 | |
304 | |
305 | Transform (me : mutable; T : Trsf2d); |
306 | ---Purpose : Applies the transformation T to this offset curve. |
307 | -- Note: the basis curve is also modified. |
308 | |
309 | TransformedParameter(me; U : Real; T : Trsf2d from gp) returns Real |
310 | ---Purpose: Returns the parameter on the transformed curve for |
311 | -- the transform of the point of parameter U on <me>. |
312 | -- |
313 | -- me->Transformed(T)->Value(me->TransformedParameter(U,T)) |
314 | -- |
315 | -- is the same point as |
316 | -- |
317 | -- me->Value(U).Transformed(T) |
318 | -- |
319 | -- This methods calls the basis curve method. |
320 | is redefined; |
321 | |
322 | ParametricTransformation(me; T : Trsf2d from gp) returns Real |
323 | ---Purpose: Returns a coefficient to compute the parameter on |
324 | -- the transformed curve for the transform of the |
325 | -- point on <me>. |
326 | -- |
327 | -- Transformed(T)->Value(U * ParametricTransformation(T)) |
328 | -- |
329 | -- is the same point as |
330 | -- |
331 | -- Value(U).Transformed(T) |
332 | -- |
333 | -- This methods calls the basis curve method. |
334 | is redefined; |
335 | |
336 | |
337 | |
338 | Copy (me) returns mutable like me; |
339 | ---Purpose: Creates a new object, which is a copy of this offset curve. |
340 | fields |
341 | |
342 | basisCurve : Curve from Geom2d; |
343 | offsetValue : Real; |
344 | |
345 | end; |