1 #define INKSCAPE_LPE_SKELETAL_STROKES_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-skeletalstrokes.h"
10 #include "sp-shape.h"
11 #include "display/curve.h"
12 #include <libnr/n-art-bpath.h>
13 #include "live_effects/n-art-bpath-2geom.h"
14 #include "svg/svg.h"
15 #include "ui/widget/scalar.h"
17 #include <2geom/sbasis.h>
18 #include <2geom/sbasis-geometric.h>
19 #include <2geom/bezier-to-sbasis.h>
20 #include <2geom/sbasis-to-bezier.h>
21 #include <2geom/d2.h>
22 #include <2geom/piecewise.h>
24 #include <algorithm>
25 using std::vector;
28 /* Theory in e-mail from J.F. Barraud
29 Let B be the skeleton path, and P the pattern (the path to be deformed).
31 P is a map t --> P(t) = ( x(t), y(t) ).
32 B is a map t --> B(t) = ( a(t), b(t) ).
34 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
35 U(s) is s itself.
37 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).
39 The basic deformation associated to B is then given by:
41 (x,y) --> U(x)+y*N(x)
43 (i.e. we go for distance x along the path, and then for distance y along the normal)
45 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
46 first) but I think we can first forget about them.
47 */
49 namespace Inkscape {
50 namespace LivePathEffect {
52 static const Util::EnumData<SkelCopyType> SkelCopyTypeData[SSCT_END] = {
53 {SSCT_SINGLE, N_("Single"), "single"},
54 {SSCT_SINGLE_STRETCHED, N_("Single, stretched"), "single_stretched"},
55 {SSCT_REPEATED, N_("Repeated"), "repeated"},
56 {SSCT_REPEATED_STRETCHED, N_("Repeated, stretched"), "repeated_stretched"}
57 };
58 static const Util::EnumDataConverter<SkelCopyType> SkelCopyTypeConverter(SkelCopyTypeData, SSCT_END);
60 LPESkeletalStrokes::LPESkeletalStrokes(LivePathEffectObject *lpeobject) :
61 Effect(lpeobject),
62 pattern(_("Pattern source"), _("Path to put along the skeleton path"), "pattern", &wr, this, "M0,0 L1,0"),
63 copytype(_("Pattern copies"), _("How many pattern copies to place along the skeleton path"), "copytype", SkelCopyTypeConverter, &wr, this, SSCT_SINGLE_STRETCHED),
64 prop_scale(_("Width"), _("Width of the pattern"), "prop_scale", &wr, this, 1),
65 scale_y_rel(_("Width in units of length"), _("Scale the width of the pattern in units of its length"), "scale_y_rel", &wr, this, false),
66 spacing(_("Spacing"), _("Space between copies of the pattern"), "spacing", &wr, this, 0),
67 normal_offset(_("Normal offset"), "", "normal_offset", &wr, this, 0),
68 tang_offset(_("Tangential offset"), "", "tang_offset", &wr, this, 0),
69 vertical_pattern(_("Pattern is vertical"), "Rotate pattern 90 deg before applying", "vertical_pattern", &wr, this, false)
70 {
71 registerParameter( dynamic_cast<Parameter *>(&pattern) );
72 registerParameter( dynamic_cast<Parameter *>(©type) );
73 registerParameter( dynamic_cast<Parameter *>(&prop_scale) );
74 registerParameter( dynamic_cast<Parameter *>(&scale_y_rel) );
75 // registerParameter( dynamic_cast<Parameter *>(&spacing) );
76 // registerParameter( dynamic_cast<Parameter *>(&normal_offset) );
77 // registerParameter( dynamic_cast<Parameter *>(&tang_offset) );
78 registerParameter( dynamic_cast<Parameter *>(&vertical_pattern) );
80 prop_scale.param_set_digits(3);
81 prop_scale.param_set_increments(0.01, 0.10);
82 }
84 LPESkeletalStrokes::~LPESkeletalStrokes()
85 {
87 }
90 Geom::Piecewise<Geom::D2<Geom::SBasis> >
91 LPESkeletalStrokes::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > & pwd2_in)
92 {
93 using namespace Geom;
95 /* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */
97 SkelCopyType type = copytype.get_value();
99 Piecewise<D2<SBasis> > uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(pwd2_in),2,.1);
100 uskeleton = remove_short_cuts(uskeleton,.01);
101 Piecewise<D2<SBasis> > n = rot90(derivative(uskeleton));
102 n = force_continuity(remove_short_cuts(n,.1));
104 D2<Piecewise<SBasis> > patternd2 = make_cuts_independant(pattern);
105 Piecewise<SBasis> x = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]);
106 Piecewise<SBasis> y = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : Piecewise<SBasis>(patternd2[1]);
107 Interval pattBnds = bounds_exact(x);
108 x -= pattBnds.min();
109 Interval pattBndsY = bounds_exact(y);
110 y -= pattBndsY.middle();
112 int nbCopies = int(uskeleton.cuts.back()/pattBnds.extent());
113 double scaling = 1;
115 switch(type) {
116 case SSCT_REPEATED:
117 break;
119 case SSCT_SINGLE:
120 nbCopies = (nbCopies > 0) ? 1 : 0;
121 break;
123 case SSCT_SINGLE_STRETCHED:
124 nbCopies = 1;
125 scaling = uskeleton.cuts.back()/pattBnds.extent();
126 break;
128 case SSCT_REPEATED_STRETCHED:
129 scaling = uskeleton.cuts.back()/(((double)nbCopies)*pattBnds.extent());
130 break;
132 default:
133 return pwd2_in;
134 };
136 double pattWidth = pattBnds.extent() * scaling;
138 if (scaling != 1.0) {
139 x*=scaling;
140 }
141 if ( scale_y_rel.get_value() ) {
142 y*=(scaling*prop_scale);
143 } else {
144 if (prop_scale != 1.0) y *= prop_scale;
145 }
147 double offs = 0;
148 Piecewise<D2<SBasis> > output;
149 for (int i=0; i<nbCopies; i++){
150 output.concat(compose(uskeleton,x+offs)+y*compose(n,x+offs));
151 offs+=pattWidth;
152 }
153 return output;
154 }
157 } // namespace LivePathEffect
158 } /* namespace Inkscape */
160 /*
161 Local Variables:
162 mode:c++
163 c-file-style:"stroustrup"
164 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
165 indent-tabs-mode:nil
166 fill-column:99
167 End:
168 */
169 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :