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-rw-r--r--src/live_effects/lpe-extrude.cpp194
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diff --git a/src/live_effects/lpe-extrude.cpp b/src/live_effects/lpe-extrude.cpp
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/**
+ * @file
+ * LPE effect for extruding paths (making them "3D").
+ *
+ */
+/* Authors:
+ * Johan Engelen <j.b.c.engelen@utwente.nl>
+ *
+ * Copyright (C) 2009 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "live_effects/lpe-extrude.h"
+
+// TODO due to internal breakage in glibmm headers, this must be last:
+#include <glibmm/i18n.h>
+
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+LPEExtrude::LPEExtrude(LivePathEffectObject *lpeobject) :
+ Effect(lpeobject),
+ extrude_vector(_("Direction"), _("Defines the direction and magnitude of the extrusion"), "extrude_vector", &wr, this, Geom::Point(-10,10))
+{
+ show_orig_path = true;
+ concatenate_before_pwd2 = false;
+
+ registerParameter(&extrude_vector);
+}
+
+LPEExtrude::~LPEExtrude()
+= default;
+
+static bool are_colinear(Geom::Point a, Geom::Point b) {
+ return Geom::are_near(cross(a,b), 0., 0.5);
+}
+
+// find cusps, except at start/end for closed paths.
+// this should be factored out later.
+static std::vector<double> find_cusps( Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in ) {
+ using namespace Geom;
+ Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
+ std::vector<double> cusps;
+ // cusps are spots where the derivative jumps.
+ for (unsigned i = 1 ; i < deriv.size() ; ++i) {
+ if ( ! are_colinear(deriv[i-1].at1(), deriv[i].at0()) ) {
+ // there is a jump in the derivative, so add it to the cusps list
+ cusps.push_back(deriv.cuts[i]);
+ }
+ }
+ return cusps;
+}
+
+Geom::Piecewise<Geom::D2<Geom::SBasis> >
+LPEExtrude::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
+{
+ using namespace Geom;
+
+ // generate connecting lines (the 'sides' of the extrusion)
+ Geom::Path path(Point(0.,0.));
+ path.appendNew<Geom::LineSegment>( extrude_vector.getVector() );
+ Piecewise<D2<SBasis> > connector = path.toPwSb();
+
+ switch( 1 ) {
+ case 0: {
+ /* This one results in the following subpaths: the original, a displaced copy, and connector lines between the two
+ */
+
+ Piecewise<D2<SBasis> > pwd2_out = pwd2_in;
+ // generate extrusion bottom: (just a copy of original path, displaced a bit)
+ pwd2_out.concat( pwd2_in + extrude_vector.getVector() );
+
+ // connecting lines should be put at start and end of path if it is not closed
+ // it is not possible to check whether a piecewise<T> path is closed,
+ // so we check whether start and end are close
+ if ( ! are_near(pwd2_in.firstValue(), pwd2_in.lastValue()) ) {
+ pwd2_out.concat( connector + pwd2_in.firstValue() );
+ pwd2_out.concat( connector + pwd2_in.lastValue() );
+ }
+ // connecting lines should be put at cusps
+ Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
+ std::vector<double> cusps; // = roots(deriv);
+ for (double cusp : cusps) {
+ pwd2_out.concat( connector + pwd2_in.valueAt(cusp) );
+ }
+ // connecting lines should be put where the tangent of the path equals the extrude_vector in direction
+ std::vector<double> rts = roots(dot(deriv, rot90(extrude_vector.getVector())));
+ for (double rt : rts) {
+ pwd2_out.concat( connector + pwd2_in.valueAt(rt) );
+ }
+ return pwd2_out;
+ }
+
+ default:
+ case 1: {
+ /* This one creates separate closed subpaths that correspond to the faces of the extruded shape.
+ * When the LPE is complete, one can convert the shape to a normal path, then break subpaths apart and start coloring them.
+ */
+
+ Piecewise<D2<SBasis> > pwd2_out;
+ // split input path in pieces between points where deriv == vector
+ Piecewise<D2<SBasis> > deriv = derivative(pwd2_in);
+ std::vector<double> rts = roots(dot(deriv, rot90(extrude_vector.getVector())));
+
+ std::vector<double> cusps = find_cusps(pwd2_in);
+
+ // see if we should treat the path as being closed.
+ bool closed_path = false;
+ if ( are_near(pwd2_in.firstValue(), pwd2_in.lastValue()) ) {
+ // the path is closed, however if there is a cusp at the closing point, we should treat it as being an open path.
+ if ( are_colinear(deriv.firstValue(), deriv.lastValue()) ) {
+ // there is no jump in the derivative, so treat path as being closed
+ closed_path = true;
+ }
+ }
+
+ std::vector<double> connector_pts;
+ if (rts.empty()) {
+ connector_pts = cusps;
+ } else if (cusps.empty()) {
+ connector_pts = rts;
+ } else {
+ connector_pts = rts;
+ connector_pts.insert(connector_pts.begin(), cusps.begin(), cusps.end());
+ sort(connector_pts.begin(), connector_pts.end());
+ }
+
+ double portion_t = 0.;
+ for (unsigned i = 0; i < connector_pts.size() ; ++i) {
+ Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, connector_pts[i] );
+ portion_t = connector_pts[i];
+ if (closed_path && i == 0) {
+ // if the path is closed, skip the first cut and add it to the last cut later
+ continue;
+ }
+ Piecewise<D2<SBasis> > part = cut;
+ part.continuousConcat(connector + cut.lastValue());
+ part.continuousConcat(reverse(cut) + extrude_vector.getVector());
+ part.continuousConcat(reverse(connector) + cut.firstValue());
+ pwd2_out.concat( part );
+ }
+ if (closed_path) {
+ Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, pwd2_in.domain().max() );
+ cut.continuousConcat(portion(pwd2_in, pwd2_in.domain().min(), connector_pts[0] ));
+ Piecewise<D2<SBasis> > part = cut;
+ part.continuousConcat(connector + cut.lastValue());
+ part.continuousConcat(reverse(cut) + extrude_vector.getVector());
+ part.continuousConcat(reverse(connector) + cut.firstValue());
+ pwd2_out.concat( part );
+ } else if (!are_near(portion_t, pwd2_in.domain().max())) {
+ Piecewise<D2<SBasis> > cut = portion(pwd2_in, portion_t, pwd2_in.domain().max() );
+ Piecewise<D2<SBasis> > part = cut;
+ part.continuousConcat(connector + cut.lastValue());
+ part.continuousConcat(reverse(cut) + extrude_vector.getVector());
+ part.continuousConcat(reverse(connector) + cut.firstValue());
+ pwd2_out.concat( part );
+ }
+ return pwd2_out;
+ }
+ }
+}
+
+void
+LPEExtrude::resetDefaults(SPItem const* item)
+{
+ Effect::resetDefaults(item);
+
+ using namespace Geom;
+
+ Geom::OptRect bbox = item->geometricBounds();
+ if (bbox) {
+ Interval const &boundingbox_X = (*bbox)[Geom::X];
+ Interval const &boundingbox_Y = (*bbox)[Geom::Y];
+ extrude_vector.set_and_write_new_values( Geom::Point(boundingbox_X.middle(), boundingbox_Y.middle()),
+ (boundingbox_X.extent() + boundingbox_Y.extent())*Geom::Point(-0.05,0.2) );
+ }
+}
+
+} //namespace LivePathEffect
+} /* namespace Inkscape */
+
+/*
+ Local Variables:
+ mode:c++
+ c-file-style:"stroustrup"
+ c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
+ indent-tabs-mode:nil
+ fill-column:99
+ End:
+*/
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :