src/live_effects/lpe-extrude.cpp

   1 #define INKSCAPE_LPE_EXTRUDE_CPP
   2 /** \file
   3  * @brief LPE effect for extruding paths (making them "3D").
   4  *
   5  */
   6 /* Authors:
   7  *   Johan Engelen <j.b.c.engelen@utwente.nl>
   8  *
   9  * Copyright (C) 2009 Authors
  10  *
  11  * Released under GNU GPL, read the file 'COPYING' for more information
  12  */
  13
  14 #include "live_effects/lpe-extrude.h"
  15
  16 #include <2geom/path.h>
  17 #include <2geom/piecewise.h>
  18 #include <2geom/transforms.h>
  19 #include <algorithm>
  20
  21 namespace Inkscape {
  22 namespace LivePathEffect {
  23
  24 LPEExtrude::LPEExtrude(LivePathEffectObject *lpeobject) :
  25     Effect(lpeobject),
  26     extrude_vector(_("Direction"), _("Defines the direction and magnitude of the extrusion"), "extrude_vector", &wr, this, Geom::Point(-10,10))
  27 {
  28     show_orig_path = true;
  29     concatenate_before_pwd2 = false;
  30
  31     registerParameter( dynamic_cast<Parameter *>(&extrude_vector) );
  32 }
  33
  34 LPEExtrude::~LPEExtrude()
  35 {
  36
  37 }
  38
  39 static bool are_colinear(Geom::Point a, Geom::Point b) {
  40     return Geom::are_near(cross(a,b), 0., 0.5);
  41 }
  42
  43 // find cusps, this should be factored out later.
  44 static std::vector<double> find_cusps( Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in ) {
  45     using namespace Geom;
  46     Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
  47     std::vector<double> cusps;
  48     // cusps are spots where the derivative jumps.
  49     for (unsigned i = 1 ; i < deriv.size() ; ++i) {
  50         if ( ! are_colinear(deriv[i-1].at1(), deriv[i].at0()) ) {
  51             // there is a jump in the derivative, so add it to the cusps list
  52             cusps.push_back(deriv.cuts[i]);
  53         }
  54     }
  55     return cusps;
  56 }
  57
  58 Geom::Piecewise<Geom::D2<Geom::SBasis> >
  59 LPEExtrude::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
  60 {
  61     using namespace Geom;
  62
  63     // generate connecting lines (the 'sides' of the extrusion)
  64     Path path(Point(0.,0.));
  65     path.appendNew<Geom::LineSegment>( extrude_vector.getVector() );
  66     Piecewise<D2<SBasis> > connector = path.toPwSb();
  67
  68     switch( 1 ) {
  69     case 0: {
  70         /* This one results in the following subpaths: the original, a displaced copy, and connector lines between the two
  71          */
  72
  73         Piecewise<D2<SBasis> > pwd2_out = pwd2_in;
  74         // generate extrusion bottom: (just a copy of original path, displaced a bit)
  75         pwd2_out.concat( pwd2_in + extrude_vector.getVector() );
  76
  77         // connecting lines should be put at start and end of path if it is not closed
  78         // it is not possible to check whether a piecewise<T> path is closed,
  79         // so we check whether start and end are close
  80         if ( ! are_near(pwd2_in.firstValue(), pwd2_in.lastValue()) ) {
  81             pwd2_out.concat( connector + pwd2_in.firstValue() );
  82             pwd2_out.concat( connector + pwd2_in.lastValue() );
  83         }
  84         // connecting lines should be put at cusps
  85         Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
  86         std::vector<double> cusps; // = roots(deriv);
  87         for (unsigned i = 0; i < cusps.size() ; ++i) {
  88             pwd2_out.concat( connector + pwd2_in.valueAt(cusps[i]) );
  89         }
  90         // connecting lines should be put where the tangent of the path equals the extrude_vector in direction
  91         std::vector<double> rts = roots(dot(deriv, rot90(extrude_vector.getVector())));
  92         for (unsigned i = 0; i < rts.size() ; ++i) {
  93             pwd2_out.concat( connector + pwd2_in.valueAt(rts[i]) );
  94         }
  95         return pwd2_out;
  96     }
  97
  98     default:
  99     case 1: {
 100         /* This one creates separate closed subpaths that correspond to the faces of the extruded shape.
 101          * When the LPE is complete, one can convert the shape to a normal path, then break subpaths apart and start coloring them.
 102          */
 103
 104         Piecewise<D2<SBasis> > pwd2_out;
 105         bool closed_path = are_near(pwd2_in.firstValue(), pwd2_in.lastValue());
 106         // split input path in pieces between points where deriv == vector
 107         Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
 108         std::vector<double> rts = roots(dot(deriv, rot90(extrude_vector.getVector())));
 109
 110         std::vector<double> cusps = find_cusps(pwd2_in);
 111
 112         std::vector<double> connector_pts;
 113         if (rts.size() < 1) {
 114             connector_pts = cusps;
 115         } else if (cusps.size() < 1) {
 116             connector_pts = rts;
 117         } else {
 118             connector_pts = rts;
 119             connector_pts.insert(connector_pts.begin(), cusps.begin(), cusps.end());
 120             sort(connector_pts.begin(), connector_pts.end());
 121         }
 122
 123         double portion_t = 0.;
 124         for (unsigned i = 0; i < connector_pts.size() ; ++i) {
 125             Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, connector_pts[i] );
 126             portion_t = connector_pts[i];
 127             if (closed_path && i == 0) {
 128                 // if the path is closed, skip the first cut and add it to the last cut later
 129                 continue;
 130             }
 131             Piecewise<D2<SBasis> > part = cut;
 132             part.continuousConcat(connector + cut.lastValue());
 133             part.continuousConcat(reverse(cut) + extrude_vector.getVector());
 134             part.continuousConcat(reverse(connector) + cut.firstValue());
 135             pwd2_out.concat( part );
 136         }
 137         if (closed_path) {
 138             Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, pwd2_in.domain().max() );
 139             cut.continuousConcat(portion(pwd2_in, pwd2_in.domain().min(), connector_pts[0] ));
 140             Piecewise<D2<SBasis> > part = cut;
 141             part.continuousConcat(connector + cut.lastValue());
 142             part.continuousConcat(reverse(cut) + extrude_vector.getVector());
 143             part.continuousConcat(reverse(connector) + cut.firstValue());
 144             pwd2_out.concat( part );
 145         } else if (!are_near(portion_t, pwd2_in.domain().max())) {
 146             Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, pwd2_in.domain().max() );
 147             Piecewise<D2<SBasis> > part = cut;
 148             part.continuousConcat(connector + cut.lastValue());
 149             part.continuousConcat(reverse(cut) + extrude_vector.getVector());
 150             part.continuousConcat(reverse(connector) + cut.firstValue());
 151             pwd2_out.concat( part );
 152         }
 153         return pwd2_out;
 154     }
 155     }
 156 }
 157
 158 void
 159 LPEExtrude::resetDefaults(SPItem * item)
 160 {
 161     Effect::resetDefaults(item);
 162
 163     using namespace Geom;
 164
 165     Geom::OptRect bbox = item->getBounds(Geom::identity(), SPItem::GEOMETRIC_BBOX);
 166     if (bbox) {
 167         Interval boundingbox_X = (*bbox)[Geom::X];
 168         Interval boundingbox_Y = (*bbox)[Geom::Y];
 169         extrude_vector.set_and_write_new_values( Geom::Point(boundingbox_X.middle(), boundingbox_Y.middle()),
 170                                                  (boundingbox_X.extent() + boundingbox_Y.extent())*Geom::Point(-0.05,0.2) );
 171     }
 172 }
 173
 174 } //namespace LivePathEffect
 175 } /* namespace Inkscape */
 176
 177 /*
 178   Local Variables:
 179   mode:c++
 180   c-file-style:"stroustrup"
 181   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 182   indent-tabs-mode:nil
 183   fill-column:99
 184   End:
 185 */
 186 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :