src/live_effects/lpe-powerstroke.cpp

	lpe-powerstroke.cpp revision b8cc7b93e343f59c8deb70c7409974d385eb36ae
#define INKSCAPE_LPE_POWERSTROKE_CPP
/** \file
 * @brief  PowerStroke LPE implementation. Creates curves with modifiable stroke width.
 */
/* Authors:
 *   Johan Engelen <j.b.c.engelen@utwente.nl>
 *
 * Copyright (C) 2010 Authors
 *
 * Released under GNU GPL, read the file 'COPYING' for more information
 */

#include "live_effects/lpe-powerstroke.h"

#include "sp-shape.h"
#include "display/curve.h"

#include <2geom/path.h>
#include <2geom/piecewise.h>
#include <2geom/sbasis-geometric.h>
#include <2geom/transforms.h>


/// @TODO  Move this to 2geom
namespace Geom {
namespace Interpolate {

class Interpolator {
public:
    Interpolator() {};
    virtual ~Interpolator() {};

//    virtual Piecewise<D2<SBasis> > interpolateToPwD2Sb(std::vector<Point> points) = 0;
    virtual Path interpolateToPath(std::vector<Point> points) = 0;

private:
    Interpolator(const Interpolator&);
    Interpolator& operator=(const Interpolator&);
};

class Linear : public Interpolator {
public:
    Linear() {};
    virtual ~Linear() {};

    virtual Path interpolateToPath(std::vector<Point> points) {
        Path strokepath;
        strokepath.start( points.at(0) );
        for (unsigned int i = 1 ; i < points.size(); ++i) {
            strokepath.appendNew<Geom::LineSegment>(points.at(i));
        }
        return strokepath;
    };

private:
    Linear(const Linear&);
    Linear& operator=(const Linear&);
};

} //namespace Interpolate
} //namespace Geom

namespace Inkscape {
namespace LivePathEffect {

LPEPowerStroke::LPEPowerStroke(LivePathEffectObject *lpeobject) :
    Effect(lpeobject),
    offset_points(_("Offset points"), _("Offset points"), "offset_points", &wr, this),
    sort_points(_("Sort points"), _("Sort offset points according to their time value along the curve."), "sort_points", &wr, this, true)
{
    show_orig_path = true;

    registerParameter( dynamic_cast<Parameter *>(&offset_points) );
    registerParameter( dynamic_cast<Parameter *>(&sort_points) );
}

LPEPowerStroke::~LPEPowerStroke()
{

}


void
LPEPowerStroke::doOnApply(SPLPEItem *lpeitem)
{
    std::vector<Geom::Point> points;
    points.push_back( *(SP_SHAPE(lpeitem)->curve->first_point()) );
    Geom::Path const *path = SP_SHAPE(lpeitem)->curve->first_path();
    points.push_back( path->pointAt(path->size()/2) );
    points.push_back( *(SP_SHAPE(lpeitem)->curve->last_point()) );
    offset_points.param_set_and_write_new_value(points);
}

static bool compare_offsets (Geom::Point first, Geom::Point second)
{
    return first[Geom::X] < second[Geom::X];
}


Geom::Piecewise<Geom::D2<Geom::SBasis> >
LPEPowerStroke::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
{
    using namespace Geom;

    // perhaps use std::list instead of std::vector?
    std::vector<Geom::Point> ts(offset_points.data().size() + 2);
    // first and last point coincide with input path (for now at least)
    ts.front() = Point(pwd2_in.domain().min(),0);
    ts.back()  = Point(pwd2_in.domain().max(),0);
    for (unsigned int i = 0; i < offset_points.data().size(); ++i) {
        double t = nearest_point(offset_points.data().at(i), pwd2_in);
        double offset = L2(pwd2_in.valueAt(t) - offset_points.data().at(i));
        ts.at(i+1) = Geom::Point(t, offset);
    }

    if (sort_points) {
        sort(ts.begin(), ts.end(), compare_offsets);
    }

    // create stroke path where points (x,y) = (t, offset)
    Geom::Interpolate::Linear interpolator;
    Path strokepath = interpolator.interpolateToPath(ts);
    Path mirroredpath = strokepath.reverse() * Geom::Scale(1,-1);
    strokepath.append(mirroredpath, Geom::Path::STITCH_DISCONTINUOUS);
    strokepath.close();

    D2<Piecewise<SBasis> > patternd2 = make_cuts_independent(strokepath.toPwSb());
    Piecewise<SBasis> x = Piecewise<SBasis>(patternd2[0]);
    Piecewise<SBasis> y = Piecewise<SBasis>(patternd2[1]);

    Piecewise<D2<SBasis> > der = unitVector(derivative(pwd2_in));
    Piecewise<D2<SBasis> > n   = rot90(der);

//    output  = pwd2_in + n * offset;
//    append_half_circle(output, pwd2_in.lastValue(), n.lastValue() * offset);
//    output.continuousConcat(reverse(pwd2_in - n * offset));
//    append_half_circle(output, pwd2_in.firstValue(), -n.firstValue() * offset);

    Piecewise<D2<SBasis> > output = compose(pwd2_in,x) + y*compose(n,x);
    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:encoding=utf-8:textwidth=99 :