3
* \brief Abstract Curve Type
6
* MenTaLguY <mental@rydia.net>
7
* Marco Cecchetti <mrcekets at gmail.com>
9
* Copyright 2007-2008 authors
11
* This library is free software; you can redistribute it and/or
12
* modify it either under the terms of the GNU Lesser General Public
13
* License version 2.1 as published by the Free Software Foundation
14
* (the "LGPL") or, at your option, under the terms of the Mozilla
15
* Public License Version 1.1 (the "MPL"). If you do not alter this
16
* notice, a recipient may use your version of this file under either
17
* the MPL or the LGPL.
19
* You should have received a copy of the LGPL along with this library
20
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
21
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22
* You should have received a copy of the MPL along with this library
23
* in the file COPYING-MPL-1.1
25
* The contents of this file are subject to the Mozilla Public License
26
* Version 1.1 (the "License"); you may not use this file except in
27
* compliance with the License. You may obtain a copy of the License at
28
* http://www.mozilla.org/MPL/
30
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
31
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
32
* the specific language governing rights and limitations.
38
#ifndef _2GEOM_CURVE_H_
39
#define _2GEOM_CURVE_H_
42
#include <2geom/coord.h>
43
#include <2geom/point.h>
44
#include <2geom/interval.h>
45
#include <2geom/nearest-point.h>
46
#include <2geom/sbasis.h>
48
#include <2geom/matrix.h>
49
#include <2geom/exception.h>
61
static int root_winding(Curve const &c, Point p);
64
class Curve : private CurveHelpers {
68
virtual Point initialPoint() const = 0;
69
virtual Point finalPoint() const = 0;
71
/* isDegenerate returns true if the curve has "zero length".
72
* For a bezier curve this means for example that all handles are at the same point */
73
virtual bool isDegenerate() const = 0;
75
virtual Curve *duplicate() const = 0;
77
virtual OptRect boundsFast() const = 0;
78
virtual OptRect boundsExact() const = 0;
79
virtual OptRect boundsLocal(OptInterval i, unsigned deg) const = 0;
80
OptRect boundsLocal(OptInterval i) const { return boundsLocal(i, 0); }
82
virtual std::vector<double> roots(double v, Dim2 d) const = 0;
84
virtual int winding(Point p) const { return root_winding(*this, p); }
86
virtual int degreesOfFreedom() const { return 0;}
88
//mental: review these
89
virtual Curve *portion(double f, double t) const = 0;
90
virtual Curve *reverse() const { return portion(1, 0); }
91
virtual Curve *derivative() const = 0;
93
virtual void setInitial(Point v) = 0;
94
virtual void setFinal(Point v) = 0;
97
double nearestPoint( Point const& p, double from = 0, double to = 1 ) const
99
return nearest_point(p, toSBasis(), from, to);
104
allNearestPoints( Point const& p, double from = 0, double to = 1 ) const
106
return all_nearest_points(p, toSBasis(), from, to);
110
Path operator*=(Matrix)
111
This is not possible, because:
112
A Curve can be many things, for example a HLineSegment.
113
Such a segment cannot be transformed and stay a HLineSegment in general (take for example rotations).
114
This means that these curves become a different type of curve, hence one should use "transformed(Matrix).
117
virtual Curve *transformed(Matrix const &m) const = 0;
119
virtual Point pointAt(Coord t) const { return pointAndDerivatives(t, 0).front(); }
120
virtual Coord valueAt(Coord t, Dim2 d) const { return pointAt(t)[d]; }
121
virtual Point operator() (double t) const { return pointAt(t); }
123
/* pointAndDerivatives returns a vector that looks like the following:
124
* [ point at t, 1st derivative at t, 2nd derivative at t, ... , n'th derivative at t] */
125
virtual std::vector<Point> pointAndDerivatives(Coord t, unsigned n) const = 0;
127
/* unitTangentAt returns the unit vector tangent to the curve at position t
128
* (in the direction of increasing t). The method uses l'Hopital's rule when the derivative
129
* is (0,0), parameter n determines the maximum nr of iterations (for when higher derivatives are also (0,0) ).
130
* Point(0,0) is returned if no non-zero derivative could be found.
131
* Note that unitTangentAt(1) will probably not give the desired result. Probably one should do:
132
* Curve * c_reverse = c.reverse();
133
* Point tangent = - c_reverse->unitTangentAt(0);
136
virtual Point unitTangentAt(Coord t, unsigned n = 3) const
138
std::vector<Point> derivs = pointAndDerivatives(t, n);
139
for (unsigned deriv_n = 1; deriv_n < derivs.size(); deriv_n++) {
140
Coord length = derivs[deriv_n].length();
141
if ( ! are_near(length, 0) ) {
142
// length of derivative is non-zero, so return unit vector
143
return derivs[deriv_n] / length;
149
virtual D2<SBasis> toSBasis() const = 0;
150
virtual bool operator==(Curve const &c) const { return this == &c;}
154
Coord nearest_point(Point const& p, Curve const& c)
156
return c.nearestPoint(p);
159
} // end namespace Geom
162
#endif // _2GEOM_CURVE_H_
169
c-file-style:"stroustrup"
170
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
175
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :