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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) Johan Engelen 2007 <j.b.c.engelen@utwente.nl>
+ * Copyright 2006 Michael G. Sloan <mgsloan@gmail.com>
+ * Copyright 2006 Aaron Spike <aaron@ekips.org>
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include "live_effects/lpe-gears.h"
+#include <2geom/bezier-to-sbasis.h>
+// TODO due to internal breakage in glibmm headers, this must be last:
+#include <glibmm/i18n.h>
+
+using namespace Geom;
+
+class Gear {
+public:
+ // pitch circles touch on two properly meshed gears
+ // all measurements are taken from the pitch circle
+ double pitch_diameter() {return (_number_of_teeth * _module) / M_PI;}
+ double pitch_radius() {return pitch_diameter() / 2.0;}
+ void pitch_radius(double R) {_module = (2 * M_PI * R) / _number_of_teeth;}
+
+ // base circle serves as the basis for the involute toothe profile
+ double base_diameter() {return pitch_diameter() * cos(_pressure_angle);}
+ double base_radius() {return base_diameter() / 2.0;}
+
+ // diametrical pitch
+ double diametrical_pitch() {return _number_of_teeth / pitch_diameter();}
+
+ // height of the tooth above the pitch circle
+ double addendum() {return 1.0 / diametrical_pitch();}
+ // depth of the tooth below the pitch circle
+ double dedendum() {return addendum() + _clearance;}
+
+ // root circle specifies the bottom of the fillet between teeth
+ double root_radius() {return pitch_radius() - dedendum();}
+ double root_diameter() {return root_radius() * 2.0;}
+
+ // outer circle is the outside diameter of the gear
+ double outer_radius() {return pitch_radius() + addendum();}
+ double outer_diameter() {return outer_radius() * 2.0;}
+
+ // angle covered by the tooth on the pitch circle
+ double tooth_thickness_angle() {return M_PI / _number_of_teeth;}
+
+ Geom::Point centre() {return _centre;}
+ void centre(Geom::Point c) {_centre = c;}
+
+ double angle() {return _angle;}
+ void angle(double a) {_angle = a;}
+
+ int number_of_teeth() {return _number_of_teeth;}
+
+ Geom::Path path();
+ Gear spawn(Geom::Point p);
+
+ Gear(int n, double m, double phi)
+ : _number_of_teeth(n)
+ , _pressure_angle(phi)
+ , _module(m)
+ {
+ }
+private:
+ int _number_of_teeth;
+ double _pressure_angle;
+ double _module;
+ double _clearance = 0.0;
+ double _angle = 0.0;
+ Geom::Point _centre;
+ D2<SBasis> _involute(double start, double stop) {
+ D2<SBasis> B;
+ D2<SBasis> I;
+ Linear bo = Linear(start,stop);
+
+ B[0] = cos(bo,2);
+ B[1] = sin(bo,2);
+
+ I = B - Linear(0,1) * derivative(B);
+ I = I*base_radius() + _centre;
+ return I;
+ }
+ D2<SBasis> _arc(double start, double stop, double R) {
+ D2<SBasis> B;
+ Linear bo = Linear(start,stop);
+
+ B[0] = cos(bo,2);
+ B[1] = sin(bo,2);
+
+ B = B*R + _centre;
+ return B;
+ }
+ // angle of the base circle used to create the involute to a certain radius
+ double involute_swath_angle(double R) {
+ if (R <= base_radius()) return 0.0;
+ return sqrt(R*R - base_radius()*base_radius())/base_radius();
+ }
+
+ // angle of the base circle between the origin of the involute and the intersection on another radius
+ double involute_intersect_angle(double R) {
+ if (R <= base_radius()) return 0.0;
+ return (sqrt(R*R - base_radius()*base_radius())/base_radius()) - acos(base_radius()/R);
+ }
+};
+
+static void
+makeContinuous(D2<SBasis> &a, Point const b) {
+ for(unsigned d=0;d<2;d++)
+ a[d][0][0] = b[d];
+}
+
+Geom::Path Gear::path() {
+ Geom::Path pb;
+
+ // angle covered by a full tooth and fillet
+ double tooth_rotation = 2.0 * tooth_thickness_angle();
+ // angle covered by an involute
+ double involute_advance = involute_intersect_angle(outer_radius()) - involute_intersect_angle(root_radius());
+ // angle covered by the tooth tip
+ double tip_advance = tooth_thickness_angle() - (2 * (involute_intersect_angle(outer_radius()) - involute_intersect_angle(pitch_radius())));
+ // angle covered by the toothe root
+ double root_advance = (tooth_rotation - tip_advance) - (2.0 * involute_advance);
+ // begin drawing the involute at t if the root circle is larger than the base circle
+ double involute_t = involute_swath_angle(root_radius())/involute_swath_angle(outer_radius());
+
+ //rewind angle to start drawing from the leading edge of the tooth
+ double first_tooth_angle = _angle - ((0.5 * tip_advance) + involute_advance);
+
+ Geom::Point prev;
+ for (int i=0; i < _number_of_teeth; i++)
+ {
+ double cursor = first_tooth_angle + (i * tooth_rotation);
+
+ D2<SBasis> leading_I = compose(_involute(cursor, cursor + involute_swath_angle(outer_radius())), Linear(involute_t,1));
+ if(i != 0) makeContinuous(leading_I, prev);
+ pb.append(SBasisCurve(leading_I));
+ cursor += involute_advance;
+ prev = leading_I.at1();
+
+ D2<SBasis> tip = _arc(cursor, cursor+tip_advance, outer_radius());
+ makeContinuous(tip, prev);
+ pb.append(SBasisCurve(tip));
+ cursor += tip_advance;
+ prev = tip.at1();
+
+ cursor += involute_advance;
+ D2<SBasis> trailing_I = compose(_involute(cursor, cursor - involute_swath_angle(outer_radius())), Linear(1,involute_t));
+ makeContinuous(trailing_I, prev);
+ pb.append(SBasisCurve(trailing_I));
+ prev = trailing_I.at1();
+
+ if (base_radius() > root_radius()) {
+ Geom::Point leading_start = trailing_I.at1();
+ Geom::Point leading_end = (root_radius() * unit_vector(leading_start - _centre)) + _centre;
+ prev = leading_end;
+ pb.appendNew<LineSegment>(leading_end);
+ }
+
+ D2<SBasis> root = _arc(cursor, cursor+root_advance, root_radius());
+ makeContinuous(root, prev);
+ pb.append(SBasisCurve(root));
+ //cursor += root_advance;
+ prev = root.at1();
+
+ if (base_radius() > root_radius()) {
+ Geom::Point trailing_start = root.at1();
+ Geom::Point trailing_end = (base_radius() * unit_vector(trailing_start - _centre)) + _centre;
+ pb.appendNew<LineSegment>(trailing_end);
+ prev = trailing_end;
+ }
+ }
+
+ return pb;
+}
+
+Gear Gear::spawn(Geom::Point p) {
+ double radius = Geom::distance(this->centre(), p) - this->pitch_radius();
+ int N = (int) floor( (radius / this->pitch_radius()) * this->number_of_teeth() );
+
+ Gear gear(N, _module, _pressure_angle);
+ gear.centre(p);
+
+ double a = atan2(p - this->centre());
+ double new_angle = 0.0;
+ if (gear.number_of_teeth() % 2 == 0)
+ new_angle -= gear.tooth_thickness_angle();
+ new_angle -= (_angle) * (pitch_radius() / gear.pitch_radius());
+ new_angle += (a) * (pitch_radius() / gear.pitch_radius());
+ gear.angle(new_angle + a);
+ return gear;
+}
+
+
+
+// #################################################################
+
+
+
+namespace Inkscape {
+namespace LivePathEffect {
+
+
+LPEGears::LPEGears(LivePathEffectObject *lpeobject) :
+ Effect(lpeobject),
+ teeth(_("_Teeth:"), _("The number of teeth"), "teeth", &wr, this, 10),
+ phi(_("_Phi:"), _("Tooth pressure angle (typically 20-25 deg). The ratio of teeth not in contact."), "phi", &wr, this, 5),
+ min_radius(_("Min Radius:"), _("Minimum radius, low values can be slow"), "min_radius", &wr, this, 5.0)
+{
+ /* Tooth pressure angle: The angle between the tooth profile and a perpendicular to the pitch
+ * circle, usually at the point where the pitch circle meets the tooth profile. Standard angles
+ * are 20 and 25 degrees. The pressure angle affects the force that tends to separate mating
+ * gears. A high pressure angle means that higher ratio of teeth not in contact. However, this
+ * allows the teeth to have higher capacity and also allows fewer teeth without undercutting.
+ */
+
+ teeth.param_make_integer();
+ teeth.param_set_range(3, 1e10);
+ min_radius.param_set_range(0.01, std::numeric_limits<double>::max());
+ registerParameter(&teeth);
+ registerParameter(&phi);
+ registerParameter(&min_radius);
+}
+
+LPEGears::~LPEGears()
+= default;
+
+Geom::PathVector
+LPEGears::doEffect_path (Geom::PathVector const &path_in)
+{
+ Geom::PathVector path_out;
+ Geom::Path gearpath = path_in[0];
+
+ Geom::Path::iterator it(gearpath.begin());
+ if ( it == gearpath.end() ) return path_out;
+
+ Gear * gear = new Gear(teeth, 200.0, phi * M_PI / 180);
+ Geom::Point gear_centre = (*it).finalPoint();
+ gear->centre(gear_centre);
+ gear->angle(atan2((*it).initialPoint() - gear_centre));
+
+ ++it;
+ if ( it == gearpath.end() ) return path_out;
+ double radius = Geom::distance(gear_centre, (*it).finalPoint());
+ radius = radius < min_radius?min_radius:radius;
+ gear->pitch_radius(radius);
+
+ path_out.push_back( gear->path());
+
+ for (++it; it != gearpath.end() ; ++it) {
+ if (are_near((*it).initialPoint(), (*it).finalPoint())) {
+ continue;
+ }
+ // iterate through Geom::Curve in path_in
+ Gear* gearnew = new Gear(gear->spawn( (*it).finalPoint() ));
+ path_out.push_back( gearnew->path() );
+ delete gear;
+ gear = gearnew;
+ }
+ delete gear;
+
+ return path_out;
+}
+
+} // 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 :