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346 lines
14 KiB
Plaintext
Executable File
346 lines
14 KiB
Plaintext
Executable File
-- Created on: 1993-03-24
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-- Created by: Philippe DAUTRY
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-- Copyright (c) 1993-1999 Matra Datavision
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-- Copyright (c) 1999-2012 OPEN CASCADE SAS
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--
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-- The content of this file is subject to the Open CASCADE Technology Public
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-- License Version 6.5 (the "License"). You may not use the content of this file
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-- except in compliance with the License. Please obtain a copy of the License
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-- at http://www.opencascade.org and read it completely before using this file.
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--
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-- The Initial Developer of the Original Code is Open CASCADE S.A.S., having its
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-- main offices at: 1, place des Freres Montgolfier, 78280 Guyancourt, France.
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--
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-- The Original Code and all software distributed under the License is
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-- distributed on an "AS IS" basis, without warranty of any kind, and the
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-- Initial Developer hereby disclaims all such warranties, including without
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-- limitation, any warranties of merchantability, fitness for a particular
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-- purpose or non-infringement. Please see the License for the specific terms
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-- and conditions governing the rights and limitations under the License.
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class OffsetCurve from Geom2d inherits Curve from Geom2d
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--- Purpose :
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-- This class implements the basis services for the creation,
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-- edition, modification and evaluation of planar offset curve.
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-- The offset curve is obtained by offsetting by distance along
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-- the normal to a basis curve defined in 2D space.
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-- The offset curve in this package can be a self intersecting
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-- curve even if the basis curve does not self-intersect.
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-- The self intersecting portions are not deleted at the
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-- construction time.
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-- An offset curve is a curve at constant distance (Offset) from a
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-- basis curve and the offset curve takes its parametrization from
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-- the basis curve. The Offset curve is in the direction of the
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-- normal to the basis curve N.
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-- The distance offset may be positive or negative to indicate the
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-- preferred side of the curve :
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-- . distance offset >0 => the curve is in the direction of N
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-- . distance offset >0 => the curve is in the direction of - N
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-- On the Offset curve :
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-- Value(u) = BasisCurve.Value(U) + (Offset * (T ^ Z)) / ||T ^ Z||
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-- where T is the tangent vector to the basis curve and Z the
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-- direction of the normal vector to the plane of the curve,
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-- N = T ^ Z defines the offset direction and should not have
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-- null length.
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--
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-- Warnings :
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-- In this package we suppose that the continuity of the offset
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-- curve is one degree less than the continuity of the
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-- basis curve and we don't check that at any point ||T^Z|| != 0.0
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--
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-- So to evaluate the curve it is better to check that the offset
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-- curve is well defined at any point because an exception could
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-- be raised. The check is not done in this package at the creation
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-- of the offset curve because the control needs the use of an
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-- algorithm which cannot be implemented in this package.
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-- The OffsetCurve is closed if the first point and the last point
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-- are the same (The distance between these two points is lower or
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-- equal to the Resolution sea package gp) . The OffsetCurve can be
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-- closed even if the basis curve is not closed.
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uses Dir2d from gp,
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Pnt2d from gp,
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Trsf2d from gp,
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Vec2d from gp,
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Curve from Geom2d,
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Geometry from Geom2d,
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Shape from GeomAbs
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raises ConstructionError from Standard,
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RangeError from Standard,
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NoSuchObject from Standard,
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UndefinedDerivative from Geom2d,
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UndefinedValue from Geom2d,
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NotImplemented from Standard
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is
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Create (C : Curve from Geom2d; Offset : Real) returns mutable OffsetCurve
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--- Purpose : Constructs a curve offset from the basis curve C,
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-- where Offset is the distance between the offset
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-- curve and the basis curve at any point.
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-- A point on the offset curve is built by measuring the
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-- offset value along a normal vector at a point on C.
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-- This normal vector is obtained by rotating the
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-- vector tangential to C at 90 degrees in the
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-- anti-trigonometric sense. The side of C on which
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-- the offset value is measured is indicated by this
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-- normal vector if Offset is positive, or in the inverse
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-- sense if Offset is negative.
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-- Warnings :
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-- In this package the entities are not shared. The OffsetCurve is
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-- built with a copy of the curve C. So when C is modified the
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-- OffsetCurve is not modified
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-- Warning! ConstructionError raised if the basis curve C is not at least C1.
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-- No check is done to know if ||V^Z|| != 0.0 at any point.
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raises ConstructionError;
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Reverse (me : mutable);
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--- Purpose : Changes the direction of parametrization of <me>.
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-- As a result:
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-- - the basis curve is reversed,
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-- - the start point of the initial curve becomes the end
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-- point of the reversed curve,
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-- - the end point of the initial curve becomes the start
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-- point of the reversed curve, and
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-- - the first and last parameters are recomputed.
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ReversedParameter(me; U : Real) returns Real;
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---Purpose: Computes the parameter on the reversed curve for
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-- the point of parameter U on this offset curve.
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SetBasisCurve (me : mutable; C : Curve from Geom2d)
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raises ConstructionError;
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--- Purpose : Changes this offset curve by assigning C as the
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-- basis curve from which it is built.
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-- Exceptions
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-- Standard_ConstructionError if the curve C is not at least "C1" continuous.
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SetOffsetValue (me : mutable; D : Real);
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--- Purpose : Changes this offset curve by assigning D as the offset value.
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BasisCurve (me) returns Curve from Geom2d;
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--- Purpose : Returns the basis curve of this offset curve. The basis curve can be an offset curve.
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Continuity (me) returns Shape from GeomAbs;
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--- Purpose :
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-- Continuity of the Offset curve :
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-- C0 : only geometric continuity,
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-- C1 : continuity of the first derivative all along the Curve,
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-- C2 : continuity of the second derivative all along the Curve,
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-- C3 : continuity of the third derivative all along the Curve,
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-- G1 : tangency continuity all along the Curve,
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-- G2 : curvature continuity all along the Curve,
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-- CN : the order of continuity is infinite.
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-- Warnings :
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-- Returns the continuity of the basis curve - 1.
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-- The offset curve must have a unique normal direction defined
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-- at any point.
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--- Purpose : Value and derivatives
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--
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-- Warnings :
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-- The exception UndefinedValue or UndefinedDerivative is
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-- raised if it is not possible to compute a unique offset
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-- direction.
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-- If T is the first derivative with not null length and
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-- Z the direction normal to the plane of the curve, the
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-- relation ||T(U) ^ Z|| != 0 must be satisfied to evaluate
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-- the offset curve.
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-- No check is done at the creation time and we suppose
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-- in this package that the offset curve is well defined.
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D0 (me; U : Real; P : out Pnt2d)
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raises UndefinedValue;
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---Purpose: Warning! this should not be called
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-- if the basis curve is not at least C1. Nevertheless
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-- if used on portion where the curve is C1, it is OK
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D1 (me; U : Real; P : out Pnt2d; V1 : out Vec2d)
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raises UndefinedDerivative;
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---Purpose: Warning! this should not be called
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-- if the continuity of the basis curve is not C2.
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-- Nevertheless, it's OK to use it on portion
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-- where the curve is C2
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D2 (me; U : Real; P : out Pnt2d; V1, V2 : out Vec2d)
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raises UndefinedDerivative;
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---Purpose: Warning! This should not be called
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-- if the continuity of the basis curve is not C3.
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-- Nevertheless, it's OK to use it on portion
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-- where the curve is C3
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D3 (me; U : Real; P : out Pnt2d; V1, V2, V3 : out Vec2d)
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raises UndefinedDerivative;
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---Purpose: Warning! This should not be called
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-- if the continuity of the basis curve is not C4.
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-- Nevertheless, it's OK to use it on portion
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-- where the curve is C4
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DN (me; U : Real; N : Integer) returns Vec2d
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--- Purpose : The returned vector gives the value of the derivative
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-- for the order of derivation N.
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-- Warning! this should not be called
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-- raises UndefunedDerivative if the continuity of the basis curve is not CN+1.
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-- Nevertheless, it's OK to use it on portion
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-- where the curve is CN+1
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-- raises RangeError if N < 1.
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-- raises NotImplemented if N > 3.
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raises UndefinedDerivative,
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RangeError,
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NotImplemented;
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--- Purpose : The following functions compute the value and derivatives
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-- on the offset curve and returns the derivatives on the
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-- basis curve too.
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-- The computation of the value and derivatives on the basis
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-- curve are used to evaluate the offset curve
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-- Warnings :
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-- The exception UndefinedValue or UndefinedDerivative is
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-- raised if it is not possible to compute a unique offset direction.
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Value (me; U : Real; P, Pbasis : out Pnt2d; V1basis : out Vec2d)
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raises UndefinedValue;
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---Purpose: Warning! this should not be called
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-- if the basis curve is not at least C1. Nevertheless
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-- if used on portion where the curve is C1, it is OK
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D1 (me; U : Real; P, Pbasis : out Pnt2d;
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V1, V1basis, V2basis : out Vec2d)
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raises UndefinedDerivative;
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---Purpose: Warning! this should not be called
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-- if the continuity of the basis curve is not C1.
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-- Nevertheless, it's OK to use it on portion
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-- where the curve is C1
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D2 (me; U : Real; P, Pbasis : out Pnt2d; V1, V2, V1basis, V2basis,
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V3basis : out Vec2d)
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raises UndefinedDerivative;
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---Purpose: Warning! this should not be called
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-- if the continuity of the basis curve is not C3.
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-- Nevertheless, it's OK to use it on portion
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-- where the curve is C3
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FirstParameter (me) returns Real;
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LastParameter (me) returns Real;
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---Purpose: Returns the value of the first or last parameter of this
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-- offset curve. The first parameter corresponds to the
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-- start point of the curve. The last parameter
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-- corresponds to the end point.
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-- Note: the first and last parameters of this offset curve
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-- are also the ones of its basis curve.
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Offset (me) returns Real;
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---Purpose: Returns the offset value of this offset curve.
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IsClosed (me) returns Boolean;
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--- Purpose :
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-- Returns True if the distance between the start point
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-- and the end point of the curve is lower or equal to
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-- Resolution from package gp.
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IsCN (me; N : Integer) returns Boolean
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--- Purpose : Is the order of continuity of the curve N ?
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-- Warnings :
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-- This method answer True if the continuity of the basis curve
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-- is N + 1. We suppose in this class that a normal direction
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-- to the basis curve (used to compute the offset curve) is
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-- defined at any point on the basis curve.
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raises RangeError;
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--- Purpose : Raised if N < 0.
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IsPeriodic (me) returns Boolean;
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--- Purpose : Is the parametrization of a curve is periodic ?
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-- If the basis curve is a circle or an ellipse the corresponding
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-- OffsetCurve is periodic. If the basis curve can't be periodic
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-- (for example BezierCurve) the OffsetCurve can't be periodic.
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Period (me) returns Real from Standard
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---Purpose: Returns the period of this offset curve, i.e. the period
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-- of the basis curve of this offset curve.
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-- Exceptions
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-- Standard_NoSuchObject if the basis curve is not periodic.
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raises NoSuchObject from Standard
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is redefined;
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Transform (me : mutable; T : Trsf2d);
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---Purpose : Applies the transformation T to this offset curve.
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-- Note: the basis curve is also modified.
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TransformedParameter(me; U : Real; T : Trsf2d from gp) returns Real
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---Purpose: Returns the parameter on the transformed curve for
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-- the transform of the point of parameter U on <me>.
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--
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-- me->Transformed(T)->Value(me->TransformedParameter(U,T))
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--
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-- is the same point as
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--
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-- me->Value(U).Transformed(T)
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--
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-- This methods calls the basis curve method.
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is redefined;
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ParametricTransformation(me; T : Trsf2d from gp) returns Real
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---Purpose: Returns a coefficient to compute the parameter on
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-- the transformed curve for the transform of the
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-- point on <me>.
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--
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-- Transformed(T)->Value(U * ParametricTransformation(T))
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--
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-- is the same point as
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--
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-- Value(U).Transformed(T)
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--
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-- This methods calls the basis curve method.
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is redefined;
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Copy (me) returns mutable like me;
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---Purpose: Creates a new object, which is a copy of this offset curve.
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fields
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basisCurve : Curve from Geom2d;
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offsetValue : Real;
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end;
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