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#define INKSCAPE_LPE_SKELETAL_STROKES_CPP
/*
* Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
#include "live_effects/lpe-skeletalstrokes.h"
#include "sp-shape.h"
#include "display/curve.h"
#include <libnr/n-art-bpath.h>
#include "live_effects/n-art-bpath-2geom.h"
#include "svg/svg.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 {
static const Util::EnumData<SkelCopyType> SkelCopyTypeData[SSCT_END] = {
{SSCT_SINGLE, N_("Single"), "single"},
{SSCT_SINGLE_STRETCHED, N_("Single, stretched"), "single_stretched"},
{SSCT_REPEATED, N_("Repeated"), "repeated"},
{SSCT_REPEATED_STRETCHED, N_("Repeated, stretched"), "repeated_stretched"}
};
static const Util::EnumDataConverter<SkelCopyType> SkelCopyTypeConverter(SkelCopyTypeData, SSCT_END);
LPESkeletalStrokes::LPESkeletalStrokes(LivePathEffectObject *lpeobject) :
Effect(lpeobject),
pattern(_("Pattern"), _("Path to put along path"), "pattern", &wr, this, "M0,0 L1,1"),
copytype(_("Copytype"), _("How to shape the pattern path along the path"), "copytype", SkelCopyTypeConverter, &wr, this, SSCT_SINGLE_STRETCHED)
{
registerParameter( dynamic_cast<Parameter *>(&pattern) );
registerParameter( dynamic_cast<Parameter *>(©type) );
}
LPESkeletalStrokes::~LPESkeletalStrokes()
{
}
Geom::Piecewise<Geom::D2<Geom::SBasis> >
LPESkeletalStrokes::doEffect (Geom::Piecewise<Geom::D2<Geom::SBasis> > & pwd2_in)
{
using namespace Geom;
/* LOTS OF CODE COPIED FROM 2geom/src/toys/path-along-path.cpp
* All credits should go to jfb and mgsloan of lib2geom development! */
SkelCopyType type = copytype.get_value();
Piecewise<D2<SBasis> > uskeleton = arc_length_parametrization(Piecewise<D2<SBasis> >(pwd2_in),2,.1);
uskeleton = remove_short_cuts(uskeleton,.01);
Piecewise<D2<SBasis> > n = rot90(derivative(uskeleton));
n = force_continuity(remove_short_cuts(n,.1));
D2<Piecewise<SBasis> > patternd2 = make_cuts_independant(pattern);
Piecewise<SBasis> x=Piecewise<SBasis>(patternd2[0]);
Piecewise<SBasis> y=Piecewise<SBasis>(patternd2[1]);
Interval pattBnds = bounds_exact(x);
x -= pattBnds.min();
Interval pattBndsY = bounds_exact(y);
y -= (pattBndsY.max()+pattBndsY.min())/2;
int nbCopies = int(uskeleton.cuts.back()/pattBnds.extent());
double scaling = 1;
switch(type) {
case SSCT_REPEATED:
break;
case SSCT_SINGLE:
nbCopies = (nbCopies > 0) ? 1 : 0;
break;
case SSCT_SINGLE_STRETCHED:
nbCopies = 1;
scaling = uskeleton.cuts.back()/pattBnds.extent();
break;
case SSCT_REPEATED_STRETCHED:
scaling = uskeleton.cuts.back()/(((double)nbCopies)*pattBnds.extent());
break;
default:
return pwd2_in;
};
double pattWidth = pattBnds.extent() * scaling;
if (scaling != 1)
x*=scaling;
double offs = 0;
Piecewise<D2<SBasis> > output;
for (int i=0; i<nbCopies; i++){
output.concat(compose(uskeleton,x+offs)+y*compose(n,x+offs));
offs+=pattWidth;
}
return output;
}
} // 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 :
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