1 #define INKSCAPE_LPE_PATHALONGPATH_CPP
3 /*
4 * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
5 *
6 * Released under GNU GPL, read the file 'COPYING' for more information
7 */
9 #include "live_effects/lpe-pathalongpath.h"
10 #include "sp-shape.h"
11 #include "sp-item.h"
12 #include "sp-path.h"
13 #include "display/curve.h"
14 #include <libnr/n-art-bpath.h>
15 #include <libnr/nr-matrix-fns.h>
16 #include "live_effects/n-art-bpath-2geom.h"
17 #include "svg/svg.h"
18 #include "ui/widget/scalar.h"
20 #include <2geom/sbasis.h>
21 #include <2geom/sbasis-geometric.h>
22 #include <2geom/bezier-to-sbasis.h>
23 #include <2geom/sbasis-to-bezier.h>
24 #include <2geom/d2.h>
25 #include <2geom/piecewise.h>
27 #include <algorithm>
28 using std::vector;
31 /* Theory in e-mail from J.F. Barraud
32 Let B be the skeleton path, and P the pattern (the path to be deformed).
34 P is a map t --> P(t) = ( x(t), y(t) ).
35 B is a map t --> B(t) = ( a(t), b(t) ).
37 The first step is to re-parametrize B by its arc length: this is the parametrization in which a point p on B is located by its distance s from start. One obtains a new map s --> U(s) = (a'(s),b'(s)), that still describes the same path B, but where the distance along B from start to
38 U(s) is s itself.
40 We also need a unit normal to the path. This can be obtained by computing a unit tangent vector, and rotate it by 90°. Call this normal vector N(s).
42 The basic deformation associated to B is then given by:
44 (x,y) --> U(x)+y*N(x)
46 (i.e. we go for distance x along the path, and then for distance y along the normal)
48 Of course this formula needs some minor adaptations (as is it depends on the absolute position of P for instance, so a little translation is needed
49 first) but I think we can first forget about them.
50 */
52 namespace Inkscape {
53 namespace LivePathEffect {
55 LPEPathAlongPath::LPEPathAlongPath(LivePathEffectObject *lpeobject) :
56 Effect(lpeobject),
57 bend_path(_("Bend path"), _("Path along which to bend the original path"), "bendpath", &wr, this, "M0,0 L1,0"),
58 prop_scale(_("Width"), _("Width of the path"), "prop_scale", &wr, this, 1),
59 scale_y_rel(_("Width in units of length"), _("Scale the width of the path in units of its length"), "scale_y_rel", &wr, this, false),
60 vertical_pattern(_("Original path is vertical"), _("Rotates the original 90 degrees, before bending it along the bend path"), "vertical", &wr, this, false)
61 {
62 registerParameter( dynamic_cast<Parameter *>(&bend_path) );
63 registerParameter( dynamic_cast<Parameter *>(&prop_scale) );
64 registerParameter( dynamic_cast<Parameter *>(&scale_y_rel) );
65 registerParameter( dynamic_cast<Parameter *>(&vertical_pattern) );
67 prop_scale.param_set_digits(3);
68 prop_scale.param_set_increments(0.01, 0.10);
69 }
71 LPEPathAlongPath::~LPEPathAlongPath()
72 {
74 }
77 Geom::Piecewise<Geom::D2<Geom::SBasis> >
78 LPEPathAlongPath::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > & pwd2_in)
79 {
80 using namespace Geom;
82 /* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */
84 Piecewise<D2<SBasis> > uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(bend_path),2,.1);
85 uskeleton = remove_short_cuts(uskeleton,.01);
86 Piecewise<D2<SBasis> > n = rot90(derivative(uskeleton));
87 n = force_continuity(remove_short_cuts(n,.1));
89 D2<Piecewise<SBasis> > patternd2 = make_cuts_independant(pwd2_in);
90 Piecewise<SBasis> x = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]);
91 Piecewise<SBasis> y = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : Piecewise<SBasis>(patternd2[1]);
92 Interval pattBnds = bounds_exact(x);
93 x -= pattBnds.min();
94 Interval pattBndsY = bounds_exact(y);
95 y -= pattBndsY.middle();
97 double scaling = uskeleton.cuts.back()/pattBnds.extent();
99 if (scaling != 1.0) {
100 x*=scaling;
101 }
103 if ( scale_y_rel.get_value() ) {
104 y*=(scaling*prop_scale);
105 } else {
106 if (prop_scale != 1.0) y *= prop_scale;
107 }
109 Piecewise<D2<SBasis> > output = compose(uskeleton,x) + y*compose(n,x);
110 return output;
111 }
113 void
114 LPEPathAlongPath::resetDefaults(SPItem * item)
115 {
116 if (!SP_IS_PATH(item)) return;
118 using namespace Geom;
120 // set the bend path to run horizontally in the middle of the bounding box of the original path
121 Piecewise<D2<SBasis> > pwd2;
122 std::vector<Geom::Path> temppath = SVGD_to_2GeomPath( SP_OBJECT_REPR(item)->attribute("inkscape:original-d"));
123 for (unsigned int i=0; i < temppath.size(); i++) {
124 pwd2.concat( temppath[i].toPwSb() );
125 }
127 D2<Piecewise<SBasis> > d2pw = make_cuts_independant(pwd2);
128 Interval bndsX = bounds_exact(d2pw[0]);
129 Interval bndsY = bounds_exact(d2pw[1]);
130 Point start(bndsX.min(), (bndsY.max()+bndsY.min())/2);
131 Point end(bndsX.max(), (bndsY.max()+bndsY.min())/2);
133 if ( Geom::are_near(start,end) ) {
134 end += Point(1.,0.);
135 }
136 Geom::Path path;
137 path.start( start );
138 path.appendNew<Geom::LineSegment>( end );
139 bend_path.param_set_and_write_new_value( path.toPwSb() );
140 }
142 void
143 LPEPathAlongPath::transform_multiply(Geom::Matrix const& postmul, bool set)
144 {
145 // TODO: implement correct transformation instead of this default behavior
146 Effect::transform_multiply(postmul, set);
147 }
150 } // namespace LivePathEffect
151 } /* namespace Inkscape */
153 /*
154 Local Variables:
155 mode:c++
156 c-file-style:"stroustrup"
157 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
158 indent-tabs-mode:nil
159 fill-column:99
160 End:
161 */
162 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :