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-- File: Adaptor2d.cdl
-- Created: Thu Oct 8 10:33:07 1992
-- Author: Isabelle GRIGNON
-- <isg@sdsun2>
---Copyright: Matra Davision 1992
package Adaptor2d
---Purpose: The Adaptor2d package is used to help defining
-- reusable geometric algorithms. i.e. that can be
-- used on curves and surfaces.
--
-- It defines general services for objects :
--
-- - the 2d curve. Curve2d
--
-- The services are :
--
-- - Usual services found in Geom or Geom2d :
--
-- * parameter range, value and derivatives, etc...
--
-- - Continuity breakout services :
--
-- * Allows to divide a curve or a surfaces in
-- parts with a given derivation order.
--
-- - Special geometries detection services :
--
-- * Allows to test for special cases that can
-- be processed more easily :
-- - Conics, Quadrics, Bezier, BSpline ...
--
-- And to get the correponding data form the
-- package gp or Geom. The special type
-- OtherCurve means that no special case has
-- been detected and the algorithm may use
-- only the evaluation methods (D0, D1, ...)
--
--
-- For each category Curve2d, Curve, Surface we
-- define three classes, we illustrate now the
-- principles with the Curve, the same applies to
-- Curve2d and Surface.
--
-- The class Curve is the abstract root for all
-- Curves used by algorithms, it is handled by value
-- and provides as deferred methods the services
-- described above.
--
-- Some services (breakout) requires to create new
-- curves, this leads to memory allocation
-- considerations (who create the curve, who deletes
-- it ?). To solve this problem elegantly the curve
-- will return a HCurve, the HCurve is a curve
-- handled by reference so it will be deallocated
-- automatically when it is not used.
--
-- A third class GenHCurve is provided, this class is
-- generic and its utility is to provide automatic
-- generation of the HCurve class when you have
-- written the Curve class.
--
--
-- * Let us show an example (with 2d curves) :
--
-- Imagine an algorithm to intersect curves, this
-- algorithms is written to process Curve2d from
-- Adaptor2d :
--
-- A method may look like :
--
-- Intersect(C1,C2 : Curve2d from Adaptor2d);
--
-- Which will look like in C++
--
-- Intersect(const Adaptor2d_Curve2d& C1,
-- const Adaptor2d_Curve2d& C2)
-- {
-- // you can call any method
-- Standard_Real first1 = C1.FirstParameter();
--
-- // but avoid to copy in an Adaptor2d_Curve which
-- // is an Abstract class, use a reference or a pointer
--
-- const Adaptor2d_Curve& C = C1;
-- const Adaptor2d_Curve *pC = &C1;
--
-- // If you are interseted in Intervals you must
-- // store them in a HCurve to ensure they are kept
-- // in memory. Then a referrence may be used.
--
-- Handle(Adaptor2d_HCurve) HCI = C1.Interval(1);
--
-- const Adaptor2d_Curve& CI = HCI->Curve();
-- pC = &(HCI->Curve());
--
--
-- * The Adaptor2d provides also Generic classes
-- implementing algorithmic curves and surfaces.
--
-- - IsoCurve : Isoparametric curve on a surface.
-- - CurveOnSurface : 2D curve in the parametric
-- space of a surface.
--
--
-- - OffsetCurve2d : 2d offset curve
-- - ProjectedCurve : 3d curve projected on a plane
-- - SurfaceOfLinearExtrusion
-- - SurfaceOfRevolution
--
-- They are instantiated with HCurve, HSurface, HCurved2d
uses
Standard,
MMgt,
TColStd,
GeomAbs,
TopAbs,
TColgp,
gp,
Geom2d,
math
is
deferred class Curve2d;
---Purpose: Root of the 2d curve.
pointer Curve2dPtr to Curve2d from Adaptor2d;
deferred class HCurve2d;
---Purpose: deferred class for the 2d curves manipulated with
-- Handle.
generic class GenHCurve2d;
---Purpose: Generic class used to create a curve inheriting
-- from HCurve2d.
--
-- The following classes are used to define an abstract
-- simplified "topology" for surfaces. This is used by
-- algorithm as mass properties or surface intersections.
--
class Line2d;
class HLine2d instantiates GenHCurve2d(Line2d from Adaptor2d);
---Purpose: Use by the TopolTool to trim a surface.
--
-- The following classes provides algorithmic curves and
-- surface, they are inheriting from Curve and Surface and the
-- correponding HCurve and HSurface is instantiated.
--
--
end Adaptor2d;
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