Adding upstream version 1.0.2.upstream/1.0.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 326 insertions, 0 deletions

diff --git a/src/live_effects/lpe-powerstroke-interpolators.h b/src/live_effects/lpe-powerstroke-interpolators.h
new file mode 100644
index 0000000..940d97e
--- /dev/null
+++ b/src/live_effects/lpe-powerstroke-interpolators.h
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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 :