#define INKSCAPE_LPE_BENDPATH_CPP /* * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl> * Copyright (C) Steren Giannini 2008 <steren.giannini@gmail.com> * * Released under GNU GPL, read the file 'COPYING' for more information */ #include "live_effects/lpe-bendpath.h" #include "sp-shape.h" #include "sp-item.h" #include "sp-path.h" #include "sp-item-group.h" #include "svg/svg.h" #include "ui/widget/scalar.h" #include <2geom/sbasis.h> #include <2geom/sbasis-geometric.h> #include <2geom/bezier-to-sbasis.h> #include <2geom/sbasis-to-bezier.h> #include <2geom/d2.h> #include <2geom/piecewise.h> #include <algorithm> using std::vector; /* Theory in e-mail from J.F. Barraud Let B be the skeleton path, and P the pattern (the path to be deformed). P is a map t --> P(t) = ( x(t), y(t) ). B is a map t --> B(t) = ( a(t), b(t) ). 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 U(s) is s itself. 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). The basic deformation associated to B is then given by: (x,y) --> U(x)+y*N(x) (i.e. we go for distance x along the path, and then for distance y along the normal) 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 first) but I think we can first forget about them. */ namespace Inkscape { namespace LivePathEffect { LPEBendPath::LPEBendPath(LivePathEffectObject *lpeobject) : Effect(lpeobject), bend_path(_("Bend path"), _("Path along which to bend the original path"), "bendpath", &wr, this, "M0,0 L1,0"), prop_scale(_("Width"), _("Width of the path"), "prop_scale", &wr, this, 1), scale_y_rel(_("Width in units of length"), _("Scale the width of the path in units of its length"), "scale_y_rel", &wr, this, false), vertical_pattern(_("Original path is vertical"), _("Rotates the original 90 degrees, before bending it along the bend path"), "vertical", &wr, this, false) { registerParameter( dynamic_cast<Parameter *>(&bend_path) ); registerParameter( dynamic_cast<Parameter *>(&prop_scale) ); registerParameter( dynamic_cast<Parameter *>(&scale_y_rel) ); registerParameter( dynamic_cast<Parameter *>(&vertical_pattern) ); prop_scale.param_set_digits(3); prop_scale.param_set_increments(0.01, 0.10); concatenate_before_pwd2 = true; } LPEBendPath::~LPEBendPath() { } void LPEBendPath::doBeforeEffect (SPLPEItem *lpeitem) { // get the item bounding box original_bbox(lpeitem); } Geom::Piecewise<Geom::D2<Geom::SBasis> > LPEBendPath::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in) { using namespace Geom; /* Much credit should go to jfb and mgsloan of lib2geom development for the code below! */ if (bend_path.changed) { uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(bend_path.get_pwd2()),2,.1); uskeleton = remove_short_cuts(uskeleton,.01); n = rot90(derivative(uskeleton)); n = force_continuity(remove_short_cuts(n,.1)); bend_path.changed = false; } D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(pwd2_in); Piecewise<SBasis> x = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[1]) : Piecewise<SBasis>(patternd2[0]); Piecewise<SBasis> y = vertical_pattern.get_value() ? Piecewise<SBasis>(patternd2[0]) : Piecewise<SBasis>(patternd2[1]); //We use the group bounding box size or the path bbox size to translate well x and y x-= vertical_pattern.get_value() ? boundingbox_Y.min() : boundingbox_X.min(); y-= vertical_pattern.get_value() ? boundingbox_X.middle() : boundingbox_Y.middle(); double scaling = uskeleton.cuts.back()/boundingbox_X.extent(); if (scaling != 1.0) { x*=scaling; } if ( scale_y_rel.get_value() ) { y*=(scaling*prop_scale); } else { if (prop_scale != 1.0) y *= prop_scale; } Piecewise<D2<SBasis> > output = compose(uskeleton,x) + y*compose(n,x); return output; } void LPEBendPath::resetDefaults(SPItem * item) { Effect::resetDefaults(item); original_bbox(SP_LPE_ITEM(item)); Geom::Point start(boundingbox_X.min(), (boundingbox_Y.max()+boundingbox_Y.min())/2); Geom::Point end(boundingbox_X.max(), (boundingbox_Y.max()+boundingbox_Y.min())/2); if ( Geom::are_near(start,end) ) { end += Geom::Point(1.,0.); } Geom::Path path; path.start( start ); path.appendNew<Geom::LineSegment>( end ); bend_path.set_new_value( path.toPwSb(), true ); } } // 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 :