src/live_effects/lpe-powerstroke.cpp

   1 #define INKSCAPE_LPE_POWERSTROKE_CPP
   2 /** \file
   3  * @brief  PowerStroke LPE implementation. Creates curves with modifiable stroke width.
   4  */
   5 /* Authors:
   6  *   Johan Engelen <j.b.c.engelen@utwente.nl>
   7  *
   8  * Copyright (C) 2010 Authors
   9  *
  10  * Released under GNU GPL, read the file 'COPYING' for more information
  11  */
  12
  13 #include "live_effects/lpe-powerstroke.h"
  14
  15 #include "sp-shape.h"
  16 #include "display/curve.h"
  17
  18 #include <2geom/path.h>
  19 #include <2geom/piecewise.h>
  20 #include <2geom/sbasis-geometric.h>
  21 #include <2geom/svg-elliptical-arc.h>
  22 #include <2geom/transforms.h>
  23
  24 namespace Inkscape {
  25 namespace LivePathEffect {
  26
  27 LPEPowerStroke::LPEPowerStroke(LivePathEffectObject *lpeobject) :
  28     Effect(lpeobject),
  29     offset_points(_("Offset points"), _("Offset points"), "offset_points", &wr, this)
  30 {
  31     show_orig_path = true;
  32
  33     registerParameter( dynamic_cast<Parameter *>(&offset_points) );
  34 }
  35
  36 LPEPowerStroke::~LPEPowerStroke()
  37 {
  38
  39 }
  40
  41
  42 void
  43 LPEPowerStroke::doOnApply(SPLPEItem *lpeitem)
  44 {
  45     std::vector<Geom::Point> points;
  46     points.push_back( *(SP_SHAPE(lpeitem)->curve->first_point()) );
  47     Geom::Path const *path = SP_SHAPE(lpeitem)->curve->first_path();
  48     points.push_back( path->pointAt(path->size()/2) );
  49     points.push_back( *(SP_SHAPE(lpeitem)->curve->last_point()) );
  50     offset_points.param_set_and_write_new_value(points);
  51 }
  52
  53 static void append_half_circle(Geom::Piecewise<Geom::D2<Geom::SBasis> > &pwd2,
  54                                Geom::Point const center, Geom::Point const &dir) {
  55     using namespace Geom;
  56
  57     double r = L2(dir);
  58     SVGEllipticalArc cap(center + dir, r, r, angle_between(Point(1,0), dir), false, false, center - dir);
  59     Piecewise<D2<SBasis> > cap_pwd2(cap.toSBasis());
  60     pwd2.continuousConcat(cap_pwd2);
  61 }
  62
  63 Geom::Piecewise<Geom::D2<Geom::SBasis> >
  64 LPEPowerStroke::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
  65 {
  66     using namespace Geom;
  67
  68     std::vector<Geom::Point> ts(offset_points.data().size());
  69
  70     for (unsigned int i; i < ts.size(); ++i) {
  71         double t = nearest_point(offset_points.data().at(i), pwd2_in);
  72         double offset = L2(pwd2_in.valueAt(t) - offset_points.data().at(i));
  73         ts.at(i) = Geom::Point(t, offset);
  74     }
  75
  76     // create stroke path where points (x,y) = (t, offset)
  77     Path strokepath;
  78     strokepath.start( Point(pwd2_in.domain().min(),0) );
  79     for (unsigned int i = 0 ; i < ts.size(); ++i) {
  80         strokepath.appendNew<Geom::LineSegment>(ts.at(i));
  81     }
  82     strokepath.appendNew<Geom::LineSegment>( Point(pwd2_in.domain().max(), 0) );
  83     for (unsigned int i = 0; i < ts.size(); ++i) {
  84         Geom::Point temp = ts.at(ts.size() - 1 - i);
  85         strokepath.appendNew<Geom::LineSegment>( Geom::Point(temp[X], - temp[Y]) );
  86     }
  87     strokepath.close();
  88
  89     D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(strokepath.toPwSb());
  90     Piecewise<SBasis> x = Piecewise<SBasis>(patternd2[0]);
  91     Piecewise<SBasis> y = Piecewise<SBasis>(patternd2[1]);
  92
  93     Piecewise<D2<SBasis> > der = unitVector(derivative(pwd2_in));
  94     Piecewise<D2<SBasis> > n   = rot90(der);
  95
  96 //    output  = pwd2_in + n * offset;
  97 //    append_half_circle(output, pwd2_in.lastValue(), n.lastValue() * offset);
  98 //    output.continuousConcat(reverse(pwd2_in - n * offset));
  99 //    append_half_circle(output, pwd2_in.firstValue(), -n.firstValue() * offset);
 100
 101     Piecewise<D2<SBasis> > output = compose(pwd2_in,x) + y*compose(n,x);
 102     return output;
 103 }
 104
 105 /* ######################## */
 106
 107 } //namespace LivePathEffect
 108 } /* namespace Inkscape */
 109
 110 /*
 111   Local Variables:
 112   mode:c++
 113   c-file-style:"stroustrup"
 114   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 115   indent-tabs-mode:nil
 116   fill-column:99
 117   End:
 118 */
 119 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :