lpe-interpolate.cpp

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Authors:
 *   Johan Engelen
 *
 * Copyright (C) Johan Engelen 2007-2008 <j.b.c.engelen@utwente.nl>
 *
 * Released under GNU GPL v2+, read the file 'COPYING' for more information.
 */
#include "live_effects/lpe-interpolate.h"
#include <2geom/sbasis-to-bezier.h>
#include "display/curve.h"
#include "object/sp-path.h"
 
// TODO due to internal breakage in glibmm headers, this must be last:
#include <glibmm/i18n.h>
 
 
namespace Inkscape {
namespace LivePathEffect {
 
LPEInterpolate::LPEInterpolate(LivePathEffectObject *lpeobject)
    : Effect(lpeobject)
    , trajectory_path(_("Trajectory:"), _("Path along which intermediate steps are created."), "trajectory", &wr, this,
                      "M0,0 L0,0")
    , number_of_steps(_("Steps_:"), _("Determines the number of steps from start to end path."), "steps", &wr, this, 5)
    , equidistant_spacing(_("E_quidistant spacing"),
                          _("If true, the spacing between intermediates is constant along the length of the path. If "
                            "false, the distance depends on the location of the nodes of the trajectory path."),
                          "equidistant_spacing", &wr, this, true)
{
    show_orig_path = true;
 
    registerParameter(&trajectory_path);
    registerParameter(&equidistant_spacing);
    registerParameter(&number_of_steps);
 
    number_of_steps.param_make_integer();
    number_of_steps.param_set_range(2, std::numeric_limits<gint>::max());
}
 
LPEInterpolate::~LPEInterpolate() = default;
 
 
bool 
LPEInterpolate::doOnOpen(SPLPEItem const *lpeitem)
{
    if (!is_load || is_applied) {
        return false;
    }
    trajectory_path.reload();
    return false;
}
 
 
void LPEInterpolate::transform_multiply(Geom::Affine const &postmul, bool /*set*/)
{
    if (sp_lpe_item && sp_lpe_item->pathEffectsEnabled() && sp_lpe_item->optimizeTransforms()) {
        trajectory_path.param_transform_multiply(postmul, false);
    }
}
 
/*
 * interpolate path_in[0] to path_in[1]
 */
Geom::PathVector LPEInterpolate::doEffect_path(Geom::PathVector const &path_in)
{
    if ((path_in.size() < 2) || (number_of_steps < 2)) {
        return path_in;
    }
    // Don't allow empty path parameter:
    if (trajectory_path.get_pathvector().empty()) {
        return path_in;
    }
    if (is_load) {
        trajectory_path.reload();
    }
 
    Geom::PathVector path_out;
 
    Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2_A = path_in[0].toPwSb();
    Geom::Piecewise<Geom::D2<Geom::SBasis> > pwd2_B = path_in[1].toPwSb();
 
    // Transform both paths to (0,0) midpoint, so they can easily be positioned along interpolate_path
    Geom::OptRect bounds_A = Geom::bounds_exact(pwd2_A);
    if (bounds_A) {
        pwd2_A -= bounds_A->midpoint();
    }
    Geom::OptRect bounds_B = Geom::bounds_exact(pwd2_B);
    if (bounds_B) {
        pwd2_B -= bounds_B->midpoint();
    }
 
    // Make sure both paths have the same number of segments and cuts at the same locations
    pwd2_B.setDomain(pwd2_A.domain());
    Geom::Piecewise<Geom::D2<Geom::SBasis> > pA = Geom::partition(pwd2_A, pwd2_B.cuts);
    Geom::Piecewise<Geom::D2<Geom::SBasis> > pB = Geom::partition(pwd2_B, pwd2_A.cuts);
 
    auto trajectory = calculate_trajectory(bounds_A, bounds_B);
 
    Geom::Interval trajectory_domain = trajectory.domain();
 
    for (int i = 0; i < number_of_steps; ++i) {
        double fraction = i / (number_of_steps - 1);
 
        Geom::Piecewise<Geom::D2<Geom::SBasis> > pResult = pA * (1 - fraction) + pB * fraction;
        pResult += trajectory.valueAt(trajectory_domain.min() + fraction * trajectory_domain.extent());
 
        Geom::PathVector pathv = Geom::path_from_piecewise(pResult, LPE_CONVERSION_TOLERANCE);
        path_out.push_back(pathv[0]);
    }
 
    return path_out;
}
 
 
// returns the lpe parameter trajectory_path, transformed so that it starts at the
// bounding box center of the first path and ends at the bounding box center of the
// second path
Geom::Piecewise<Geom::D2<Geom::SBasis> > LPEInterpolate::calculate_trajectory(Geom::OptRect bounds_A,
                                                                              Geom::OptRect bounds_B)
{
    Geom::Affine affine = trajectory_path.get_relative_affine();
    Geom::Piecewise<Geom::D2<Geom::SBasis> > trajectory = trajectory_path.get_pathvector()[0].toPwSb() * affine;
 
    if (equidistant_spacing) {
        trajectory = Geom::arc_length_parametrization(trajectory);
    }
 
    if (!bounds_A || !bounds_B) {
        return trajectory;
    }
 
    auto trajectory_start = trajectory.firstValue();
    auto trajectory_end = trajectory.lastValue();
 
    auto midpoint_A = bounds_A->midpoint();
    auto midpoint_B = bounds_B->midpoint();
 
    Geom::Ray original(trajectory_start, trajectory_end);
    Geom::Ray transformed(midpoint_A, midpoint_B);
 
    double rotation = transformed.angle() - original.angle();
    double scale = Geom::distance(midpoint_A, midpoint_B) / Geom::distance(trajectory_start, trajectory_end);
 
    Geom::Affine transformation;
 
    transformation *= Geom::Translate(-trajectory_start);
    transformation *= Geom::Scale(scale, scale);
    transformation *= Geom::Rotate(rotation);
 
    transformation *= Geom::Translate(midpoint_A);
 
    return trajectory * transformation;
}
 
void LPEInterpolate::resetDefaults(SPItem const *item)
{
    Effect::resetDefaults(item);
 
    if (!is<SPPath>(item))
        return;
 
    auto const *crv = cast<SPPath>(item)->curveForEdit();
    Geom::PathVector const &pathv = *crv;
    if ((pathv.size() < 2))
        return;
 
    Geom::OptRect bounds_A = pathv[0].boundsExact();
    Geom::OptRect bounds_B = pathv[1].boundsExact();
 
    if (bounds_A && bounds_B) {
        Geom::PathVector traj_pathv;
        traj_pathv.push_back(Geom::Path());
        traj_pathv[0].start(bounds_A->midpoint());
        traj_pathv[0].appendNew<Geom::LineSegment>(bounds_B->midpoint());
        trajectory_path.set_new_value(traj_pathv, true);
    }
    else {
        trajectory_path.param_set_and_write_default();
    }
}
 
} // 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 :