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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 16:29:01 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 16:29:01 +0000
commit35a96bde514a8897f6f0fcc41c5833bf63df2e2a (patch)
tree657d15a03cc46bd099fc2c6546a7a4ad43815d9f /src/live_effects/lpe-powerstroke-interpolators.h
parentInitial commit. (diff)
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Adding upstream version 1.0.2.upstream/1.0.2upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/** @file
+ * Interpolators for lists of points.
+ */
+/* Authors:
+ * Johan Engelen <j.b.c.engelen@alumnus.utwente.nl>
+ *
+ * Copyright (C) 2010-2011 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#ifndef INKSCAPE_LPE_POWERSTROKE_INTERPOLATORS_H
+#define INKSCAPE_LPE_POWERSTROKE_INTERPOLATORS_H
+
+#include <2geom/path.h>
+#include <2geom/bezier-utils.h>
+#include <2geom/sbasis-to-bezier.h>
+
+#include "live_effects/spiro.h"
+
+
+/// @TODO Move this to 2geom?
+namespace Geom {
+namespace Interpolate {
+
+enum InterpolatorType {
+ INTERP_LINEAR,
+ INTERP_CUBICBEZIER,
+ INTERP_CUBICBEZIER_JOHAN,
+ INTERP_SPIRO,
+ INTERP_CUBICBEZIER_SMOOTH,
+ INTERP_CENTRIPETAL_CATMULLROM
+};
+
+class Interpolator {
+public:
+ Interpolator() = default;;
+ virtual ~Interpolator() = default;;
+
+ static Interpolator* create(InterpolatorType type);
+
+ virtual Geom::Path interpolateToPath(std::vector<Point> const &points) const = 0;
+
+private:
+ Interpolator(const Interpolator&) = delete;
+ Interpolator& operator=(const Interpolator&) = delete;
+};
+
+class Linear : public Interpolator {
+public:
+ Linear() = default;;
+ ~Linear() override = default;;
+
+ Path interpolateToPath(std::vector<Point> const &points) const override {
+ Path path;
+ path.start( points.at(0) );
+ for (unsigned int i = 1 ; i < points.size(); ++i) {
+ path.appendNew<Geom::LineSegment>(points.at(i));
+ }
+ return path;
+ };
+
+private:
+ Linear(const Linear&) = delete;
+ Linear& operator=(const Linear&) = delete;
+};
+
+// this class is terrible
+class CubicBezierFit : public Interpolator {
+public:
+ CubicBezierFit() = default;;
+ ~CubicBezierFit() override = default;;
+
+ Path interpolateToPath(std::vector<Point> const &points) const override {
+ unsigned int n_points = points.size();
+ // worst case gives us 2 segment per point
+ int max_segs = 8*n_points;
+ Geom::Point * b = g_new(Geom::Point, max_segs);
+ Geom::Point * points_array = g_new(Geom::Point, 4*n_points);
+ for (unsigned i = 0; i < n_points; ++i) {
+ points_array[i] = points.at(i);
+ }
+
+ double tolerance_sq = 0; // this value is just a random guess
+
+ int const n_segs = Geom::bezier_fit_cubic_r(b, points_array, n_points,
+ tolerance_sq, max_segs);
+
+ Geom::Path fit;
+ if ( n_segs > 0)
+ {
+ fit.start(b[0]);
+ for (int c = 0; c < n_segs; c++) {
+ fit.appendNew<Geom::CubicBezier>(b[4*c+1], b[4*c+2], b[4*c+3]);
+ }
+ }
+ g_free(b);
+ g_free(points_array);
+ return fit;
+ };
+
+private:
+ CubicBezierFit(const CubicBezierFit&) = delete;
+ CubicBezierFit& operator=(const CubicBezierFit&) = delete;
+};
+
+/// @todo invent name for this class
+class CubicBezierJohan : public Interpolator {
+public:
+ CubicBezierJohan(double beta = 0.2) {
+ _beta = beta;
+ };
+ ~CubicBezierJohan() override = default;;
+
+ Path interpolateToPath(std::vector<Point> const &points) const override {
+ Path fit;
+ fit.start(points.at(0));
+ for (unsigned int i = 1; i < points.size(); ++i) {
+ Point p0 = points.at(i-1);
+ Point p1 = points.at(i);
+ Point dx = Point(p1[X] - p0[X], 0);
+ fit.appendNew<CubicBezier>(p0+_beta*dx, p1-_beta*dx, p1);
+ }
+ return fit;
+ };
+
+ void setBeta(double beta) {
+ _beta = beta;
+ }
+
+ double _beta;
+
+private:
+ CubicBezierJohan(const CubicBezierJohan&) = delete;
+ CubicBezierJohan& operator=(const CubicBezierJohan&) = delete;
+};
+
+/// @todo invent name for this class
+class CubicBezierSmooth : public Interpolator {
+public:
+ CubicBezierSmooth(double beta = 0.2) {
+ _beta = beta;
+ };
+ ~CubicBezierSmooth() override = default;;
+
+ Path interpolateToPath(std::vector<Point> const &points) const override {
+ Path fit;
+ fit.start(points.at(0));
+ unsigned int num_points = points.size();
+ for (unsigned int i = 1; i < num_points; ++i) {
+ Point p0 = points.at(i-1);
+ Point p1 = points.at(i);
+ Point dx = Point(p1[X] - p0[X], 0);
+ if (i == 1) {
+ fit.appendNew<CubicBezier>(p0, p1-0.75*dx, p1);
+ } else if (i == points.size() - 1) {
+ fit.appendNew<CubicBezier>(p0+0.75*dx, p1, p1);
+ } else {
+ fit.appendNew<CubicBezier>(p0+_beta*dx, p1-_beta*dx, p1);
+ }
+ }
+ return fit;
+ };
+
+ void setBeta(double beta) {
+ _beta = beta;
+ }
+
+ double _beta;
+
+private:
+ CubicBezierSmooth(const CubicBezierSmooth&) = delete;
+ CubicBezierSmooth& operator=(const CubicBezierSmooth&) = delete;
+};
+
+class SpiroInterpolator : public Interpolator {
+public:
+ SpiroInterpolator() = default;;
+ ~SpiroInterpolator() override = default;;
+
+ Path interpolateToPath(std::vector<Point> const &points) const override {
+ Path fit;
+
+ Coord scale_y = 100.;
+
+ guint len = points.size();
+ Spiro::spiro_cp *controlpoints = g_new (Spiro::spiro_cp, len);
+ for (unsigned int i = 0; i < len; ++i) {
+ controlpoints[i].x = points[i][X];
+ controlpoints[i].y = points[i][Y] / scale_y;
+ controlpoints[i].ty = 'c';
+ }
+ controlpoints[0].ty = '{';
+ controlpoints[1].ty = 'v';
+ controlpoints[len-2].ty = 'v';
+ controlpoints[len-1].ty = '}';
+
+ Spiro::spiro_run(controlpoints, len, fit);
+
+ fit *= Scale(1,scale_y);
+ g_free(controlpoints);
+ return fit;
+ };
+
+private:
+ SpiroInterpolator(const SpiroInterpolator&) = delete;
+ SpiroInterpolator& operator=(const SpiroInterpolator&) = delete;
+};
+
+// Quick mockup for testing the behavior for powerstroke controlpoint interpolation
+class CentripetalCatmullRomInterpolator : public Interpolator {
+public:
+ CentripetalCatmullRomInterpolator() = default;;
+ ~CentripetalCatmullRomInterpolator() override = default;;
+
+ Path interpolateToPath(std::vector<Point> const &points) const override {
+ unsigned int n_points = points.size();
+
+ Geom::Path fit(points.front());
+
+ if (n_points < 3) return fit; // TODO special cases for 0,1 and 2 input points
+
+ // return n_points-1 cubic segments
+
+ // duplicate first point
+ fit.append(calc_bezier(points[0],points[0],points[1],points[2]));
+
+ for (std::size_t i = 0; i < n_points-2; ++i) {
+ Point p0 = points[i];
+ Point p1 = points[i+1];
+ Point p2 = points[i+2];
+ Point p3 = (i < n_points-3) ? points[i+3] : points[i+2];
+
+ fit.append(calc_bezier(p0, p1, p2, p3));
+ }
+
+ return fit;
+ };
+
+private:
+ CubicBezier calc_bezier(Point p0, Point p1, Point p2, Point p3) const {
+ // create interpolating bezier between p1 and p2
+
+ // Part of the code comes from StackOverflow user eriatarka84
+ // http://stackoverflow.com/a/23980479/2929337
+
+ // calculate time coords (deltas) of points
+ // the factor 0.25 can be generalized for other Catmull-Rom interpolation types
+ // see alpha in Yuksel et al. "On the Parameterization of Catmull-Rom Curves",
+ // --> http://www.cemyuksel.com/research/catmullrom_param/catmullrom.pdf
+ double dt0 = powf(distanceSq(p0, p1), 0.25);
+ double dt1 = powf(distanceSq(p1, p2), 0.25);
+ double dt2 = powf(distanceSq(p2, p3), 0.25);
+
+
+ // safety check for repeated points
+ double eps = Geom::EPSILON;
+ if (dt1 < eps)
+ dt1 = 1.0;
+ if (dt0 < eps)
+ dt0 = dt1;
+ if (dt2 < eps)
+ dt2 = dt1;
+
+ // compute tangents when parameterized in [t1,t2]
+ Point tan1 = (p1 - p0) / dt0 - (p2 - p0) / (dt0 + dt1) + (p2 - p1) / dt1;
+ Point tan2 = (p2 - p1) / dt1 - (p3 - p1) / (dt1 + dt2) + (p3 - p2) / dt2;
+ // rescale tangents for parametrization in [0,1]
+ tan1 *= dt1;
+ tan2 *= dt1;
+
+ // create bezier from tangents (this is already in 2geom somewhere, or should be moved to it)
+ // the tangent of a bezier curve is: B'(t) = 3(1-t)^2 (b1 - b0) + 6(1-t)t(b2-b1) + 3t^2(b3-b2)
+ // So we have to make sure that B'(0) = tan1 and B'(1) = tan2, and we already know that b0=p1 and b3=p2
+ // tan1 = B'(0) = 3 (b1 - p1) --> p1 + (tan1)/3 = b1
+ // tan2 = B'(1) = 3 (p2 - b2) --> p2 - (tan2)/3 = b2
+
+ Point b0 = p1;
+ Point b1 = p1 + tan1 / 3;
+ Point b2 = p2 - tan2 / 3;
+ Point b3 = p2;
+
+ return CubicBezier(b0, b1, b2, b3);
+ }
+
+ CentripetalCatmullRomInterpolator(const CentripetalCatmullRomInterpolator&) = delete;
+ CentripetalCatmullRomInterpolator& operator=(const CentripetalCatmullRomInterpolator&) = delete;
+};
+
+
+inline Interpolator*
+Interpolator::create(InterpolatorType type) {
+ switch (type) {
+ case INTERP_LINEAR:
+ return new Geom::Interpolate::Linear();
+ case INTERP_CUBICBEZIER:
+ return new Geom::Interpolate::CubicBezierFit();
+ case INTERP_CUBICBEZIER_JOHAN:
+ return new Geom::Interpolate::CubicBezierJohan();
+ case INTERP_SPIRO:
+ return new Geom::Interpolate::SpiroInterpolator();
+ case INTERP_CUBICBEZIER_SMOOTH:
+ return new Geom::Interpolate::CubicBezierSmooth();
+ case INTERP_CENTRIPETAL_CATMULLROM:
+ return new Geom::Interpolate::CentripetalCatmullRomInterpolator();
+ default:
+ return new Geom::Interpolate::Linear();
+ }
+}
+
+} //namespace Interpolate
+} //namespace Geom
+
+#endif
+
+/*
+ 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 :