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, except at start/end for closed paths.
  44 // this should be factored out later.
  45 static std::vector<double> find_cusps( Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in ) {
  46     using namespace Geom;
  47     Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
  48     std::vector<double> cusps;
  49     // cusps are spots where the derivative jumps.
  50     for (unsigned i = 1 ; i < deriv.size() ; ++i) {
  51         if ( ! are_colinear(deriv[i-1].at1(), deriv[i].at0()) ) {
  52             // there is a jump in the derivative, so add it to the cusps list
  53             cusps.push_back(deriv.cuts[i]);
  54         }
  55     }
  56     return cusps;
  57 }
  58
  59 Geom::Piecewise<Geom::D2<Geom::SBasis> >
  60 LPEExtrude::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
  61 {
  62     using namespace Geom;
  63
  64     // generate connecting lines (the 'sides' of the extrusion)
  65     Path path(Point(0.,0.));
  66     path.appendNew<Geom::LineSegment>( extrude_vector.getVector() );
  67     Piecewise<D2<SBasis> > connector = path.toPwSb();
  68
  69     switch( 1 ) {
  70     case 0: {
  71         /* This one results in the following subpaths: the original, a displaced copy, and connector lines between the two
  72          */
  73
  74         Piecewise<D2<SBasis> > pwd2_out = pwd2_in;
  75         // generate extrusion bottom: (just a copy of original path, displaced a bit)
  76         pwd2_out.concat( pwd2_in + extrude_vector.getVector() );
  77
  78         // connecting lines should be put at start and end of path if it is not closed
  79         // it is not possible to check whether a piecewise<T> path is closed,
  80         // so we check whether start and end are close
  81         if ( ! are_near(pwd2_in.firstValue(), pwd2_in.lastValue()) ) {
  82             pwd2_out.concat( connector + pwd2_in.firstValue() );
  83             pwd2_out.concat( connector + pwd2_in.lastValue() );
  84         }
  85         // connecting lines should be put at cusps
  86         Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
  87         std::vector<double> cusps; // = roots(deriv);
  88         for (unsigned i = 0; i < cusps.size() ; ++i) {
  89             pwd2_out.concat( connector + pwd2_in.valueAt(cusps[i]) );
  90         }
  91         // connecting lines should be put where the tangent of the path equals the extrude_vector in direction
  92         std::vector<double> rts = roots(dot(deriv, rot90(extrude_vector.getVector())));
  93         for (unsigned i = 0; i < rts.size() ; ++i) {
  94             pwd2_out.concat( connector + pwd2_in.valueAt(rts[i]) );
  95         }
  96         return pwd2_out;
  97     }
  98
  99     default:
 100     case 1: {
 101         /* This one creates separate closed subpaths that correspond to the faces of the extruded shape.
 102          * When the LPE is complete, one can convert the shape to a normal path, then break subpaths apart and start coloring them.
 103          */
 104
 105         Piecewise<D2<SBasis> > pwd2_out;
 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         // see if we should treat the path as being closed.
 113         bool closed_path = false;
 114         if ( are_near(pwd2_in.firstValue(), pwd2_in.lastValue()) ) {
 115             // the path is closed, however if there is a cusp at the closing point, we should treat it as being an open path.
 116             if ( are_colinear(deriv.firstValue(), deriv.lastValue()) ) {
 117                 // there is no jump in the derivative, so treat path as being closed
 118                 closed_path = true;
 119             }
 120         }
 121
 122         std::vector<double> connector_pts;
 123         if (rts.size() < 1) {
 124             connector_pts = cusps;
 125         } else if (cusps.size() < 1) {
 126             connector_pts = rts;
 127         } else {
 128             connector_pts = rts;
 129             connector_pts.insert(connector_pts.begin(), cusps.begin(), cusps.end());
 130             sort(connector_pts.begin(), connector_pts.end());
 131         }
 132
 133         double portion_t = 0.;
 134         for (unsigned i = 0; i < connector_pts.size() ; ++i) {
 135             Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, connector_pts[i] );
 136             portion_t = connector_pts[i];
 137             if (closed_path && i == 0) {
 138                 // if the path is closed, skip the first cut and add it to the last cut later
 139                 continue;
 140             }
 141             Piecewise<D2<SBasis> > part = cut;
 142             part.continuousConcat(connector + cut.lastValue());
 143             part.continuousConcat(reverse(cut) + extrude_vector.getVector());
 144             part.continuousConcat(reverse(connector) + cut.firstValue());
 145             pwd2_out.concat( part );
 146         }
 147         if (closed_path) {
 148             Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, pwd2_in.domain().max() );
 149             cut.continuousConcat(portion(pwd2_in, pwd2_in.domain().min(), connector_pts[0] ));
 150             Piecewise<D2<SBasis> > part = cut;
 151             part.continuousConcat(connector + cut.lastValue());
 152             part.continuousConcat(reverse(cut) + extrude_vector.getVector());
 153             part.continuousConcat(reverse(connector) + cut.firstValue());
 154             pwd2_out.concat( part );
 155         } else if (!are_near(portion_t, pwd2_in.domain().max())) {
 156             Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, pwd2_in.domain().max() );
 157             Piecewise<D2<SBasis> > part = cut;
 158             part.continuousConcat(connector + cut.lastValue());
 159             part.continuousConcat(reverse(cut) + extrude_vector.getVector());
 160             part.continuousConcat(reverse(connector) + cut.firstValue());
 161             pwd2_out.concat( part );
 162         }
 163         return pwd2_out;
 164     }
 165     }
 166 }
 167
 168 void
 169 LPEExtrude::resetDefaults(SPItem * item)
 170 {
 171     Effect::resetDefaults(item);
 172
 173     using namespace Geom;
 174
 175     Geom::OptRect bbox = item->getBounds(Geom::identity(), SPItem::GEOMETRIC_BBOX);
 176     if (bbox) {
 177         Interval boundingbox_X = (*bbox)[Geom::X];
 178         Interval boundingbox_Y = (*bbox)[Geom::Y];
 179         extrude_vector.set_and_write_new_values( Geom::Point(boundingbox_X.middle(), boundingbox_Y.middle()),
 180                                                  (boundingbox_X.extent() + boundingbox_Y.extent())*Geom::Point(-0.05,0.2) );
 181     }
 182 }
 183
 184 } //namespace LivePathEffect
 185 } /* namespace Inkscape */
 186
 187 /*
 188   Local Variables:
 189   mode:c++
 190   c-file-style:"stroustrup"
 191   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 192   indent-tabs-mode:nil
 193   fill-column:99
 194   End:
 195 */
 196 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :