More refactoring to medial axis and gap fill, more robust

t/thin.t

@@ -1,4 +1,4 @@
-use Test::More tests => 21;
+use Test::More tests => 23;
 use strict;
 use warnings;
 
@@ -8,7 +8,7 @@ BEGIN {
 }
 
 use Slic3r;
-use List::Util qw(first sum);
+use List::Util qw(first sum none);
 use Slic3r::Geometry qw(epsilon scale unscale scaled_epsilon Y);
 use Slic3r::Test;
 
@@ -91,7 +91,20 @@ if (0) {
     is scalar(@$res), 1, 'medial axis of a narrow rectangle with an extra vertex is still a single line';
     ok unscale($res->[0]->length) >= (200-100 - (120-100)) - epsilon, 'medial axis has still a reasonable length';
     ok !(grep { abs($_ - scale 150) < scaled_epsilon } map $_->[Y], map @$_, @$res2), "extra vertices don't influence medial axis";
+}
 
+{
+    my $expolygon = Slic3r::ExPolygon->new(
+        Slic3r::Polygon->new([1185881,829367],[1421988,1578184],[1722442,2303558],[2084981,2999998],[2506843,3662186],[2984809,4285086],[3515250,4863959],[4094122,5394400],[4717018,5872368],[5379210,6294226],[6075653,6656769],[6801033,6957229],[7549842,7193328],[8316383,7363266],[9094809,7465751],[9879211,7500000],[10663611,7465750],[11442038,7363265],[12208580,7193327],[12957389,6957228],[13682769,6656768],[14379209,6294227],[15041405,5872366],[15664297,5394401],[16243171,4863960],[16758641,4301424],[17251579,3662185],[17673439,3000000],[18035980,2303556],[18336441,1578177],[18572539,829368],[18750748,0],[19758422,0],[19727293,236479],[19538467,1088188],[19276136,1920196],[18942292,2726179],[18539460,3499999],[18070731,4235755],[17539650,4927877],[16950279,5571067],[16307090,6160437],[15614974,6691519],[14879209,7160248],[14105392,7563079],[13299407,7896927],[12467399,8159255],[11615691,8348082],[10750769,8461952],[9879211,8500000],[9007652,8461952],[8142729,8348082],[7291022,8159255],[6459015,7896927],[5653029,7563079],[4879210,7160247],[4143447,6691519],[3451331,6160437],[2808141,5571066],[2218773,4927878],[1687689,4235755],[1218962,3499999],[827499,2748020],[482284,1920196],[219954,1088186],[31126,236479],[0,0],[1005754,0]),
+    );
+    my $res = $expolygon->medial_axis(scale 1.324888, scale 0.25);
+    is scalar(@$res), 1, 'medial axis of a semicircumference is a single line';
+    
+    # check whether turns are all CCW or all CW
+    my @lines = @{$res->[0]->lines};
+    my @angles = map { $lines[$_-1]->ccw($lines[$_]->b) } 1..$#lines;
+    ok !!(none { $_ < 0 } @angles) || (none { $_ > 0 } @angles),
+        'all medial axis segments of a semicircumference have the same orientation';
 }
 
 {
@@ -136,7 +149,7 @@ if (0) {
 {
     my $expolygon = Slic3r::ExPolygon->new(Slic3r::Polygon->new_scale(
         [50, 100],
-        [300, 102],
+        [1000, 102],
         [50, 104],
     ));
     my $res = $expolygon->medial_axis(scale 4, scale 0.5);

xs/src/libslic3r/ExPolygon.cpp

@@ -174,17 +174,10 @@ void
 ExPolygon::medial_axis(double max_width, double min_width, ThickPolylines* polylines) const
 {
     // init helper object
-    Slic3r::Geometry::MedialAxis ma(max_width, min_width);
+    Slic3r::Geometry::MedialAxis ma(max_width, min_width, this);
-    ma.expolygon = this;
+    ma.lines = this->lines();
     
-    // populate list of segments for the Voronoi diagram
+    // compute the Voronoi diagram and extract medial axis polylines
-    ma.lines = this->contour.lines();
-    for (Polygons::const_iterator hole = this->holes.begin(); hole != this->holes.end(); ++hole) {
-        Lines lines = hole->lines();
-        ma.lines.insert(ma.lines.end(), lines.begin(), lines.end());
-    }
-    
-    // compute the Voronoi diagram
     ThickPolylines pp;
     ma.build(&pp);
     
@@ -195,15 +188,14 @@ ExPolygon::medial_axis(double max_width, double min_width, ThickPolylines* polyl
     svg.Close();
     */
     
-    // find the maximum width returned
+    /* Find the maximum width returned; we're going to use this for validating and 
+       filtering the output segments. */
     double max_w = 0;
-    if (!pp.empty()) {
-        std::vector<double> widths;
     for (ThickPolylines::const_iterator it = pp.begin(); it != pp.end(); ++it)
-            widths.insert(widths.end(), it->width.begin(), it->width.end());
+        max_w = fmaxf(max_w, *std::max_element(it->width.begin(), it->width.end()));
-        max_w = *std::max_element(widths.begin(), widths.end());
-    }
     
+    /* Loop through all returned polylines in order to extend their endpoints to the 
+       expolygon boundaries */
     bool removed = false;
     for (size_t i = 0; i < pp.size(); ++i) {
         ThickPolyline& polyline = pp[i];
@@ -502,4 +494,15 @@ ExPolygon::lines() const
     return lines;
 }
 
+std::string
+ExPolygon::dump_perl() const
+{
+    std::ostringstream ret;
+    ret << "[" << this->contour.dump_perl();
+    for (Polygons::const_iterator h = this->holes.begin(); h != this->holes.end(); ++h)
+        ret << "," << h->dump_perl();
+    ret << "]";
+    return ret.str();
+}
+
 }

xs/src/libslic3r/ExPolygon.hpp

@@ -42,6 +42,7 @@ class ExPolygon
     void triangulate_pp(Polygons* polygons) const;
     void triangulate_p2t(Polygons* polygons) const;
     Lines lines() const;
+    std::string dump_perl() const;
 };
 
 }

xs/src/libslic3r/Geometry.cpp

@@ -324,7 +324,7 @@ MedialAxis::build(ThickPolylines* polylines)
             if (edge->is_secondary() || edge->is_infinite()) continue;
         
             // don't re-validate twins
-            if (seen_edges.find(&*edge) != seen_edges.end()) continue;
+            if (seen_edges.find(&*edge) != seen_edges.end()) continue;  // TODO: is this needed?
             seen_edges.insert(&*edge);
             seen_edges.insert(edge->twin());
             
@@ -445,38 +445,48 @@ MedialAxis::validate_edge(const VD::edge_type* edge)
     }
     
     // retrieve the original line segments which generated the edge we're checking
-    const VD::cell_type* cell1 = edge->cell();
+    const VD::cell_type* cell_l = edge->cell();
-    const VD::cell_type* cell2 = edge->twin()->cell();
+    const VD::cell_type* cell_r = edge->twin()->cell();
-    const Line &segment1 = this->retrieve_segment(cell1);
+    const Line &segment_l = this->retrieve_segment(cell_l);
-    const Line &segment2 = this->retrieve_segment(cell2);
+    const Line &segment_r = this->retrieve_segment(cell_r);
     
-    /*  Calculate thickness of the section at both the endpoints of this edge.
+    /*
+    SVG svg("edge.svg");
+    svg.draw(*this->expolygon);
+    svg.draw(line);
+    svg.draw(segment_l, "red");
+    svg.draw(segment_r, "blue");
+    svg.Close();
+    */
+    
+    /*  Calculate thickness of the cross-section at both the endpoints of this edge.
         Our Voronoi edge is part of a CCW sequence going around its Voronoi cell 
-        (segment1). This edge's twin goes around segment2. Thus, segment2 is 
+        located on the left side. (segment_l).
-        oriented in the same direction as our main edge, and segment1 is oriented
+        This edge's twin goes around segment_r. Thus, segment_r is 
+        oriented in the same direction as our main edge, and segment_l is oriented
         in the same direction as our twin edge.
-        We used to only consider the (half-)distances to segment2, and that works
+        We used to only consider the (half-)distances to segment_r, and that works
-        whenever segment1 and segment2 are almost specular and facing. However, 
+        whenever segment_l and segment_r are almost specular and facing. However, 
         at curves they are staggered and they only face for a very little length
-        (such visibility actually coincides with our very short edge). This is why
+        (our very short edge represents such visibility).
-        we calculate w0 and w1 this way.
+        Both w0 and w1 can be calculated either towards cell_l or cell_r with equal
-        When cell1 or cell2 don't refer to the segment but only to an endpoint, we
+        results by Voronoi definition.
+        When cell_l or cell_r don't refer to the segment but only to an endpoint, we
         calculate the distance to that endpoint instead.  */
     
-    coordf_t w0 = cell2->contains_segment()
+    coordf_t w0 = cell_r->contains_segment()
-        ? line.a.perp_distance_to(segment2)*2
+        ? line.a.distance_to(segment_r)*2
-        : line.a.distance_to(this->retrieve_endpoint(cell2))*2;
+        : line.a.distance_to(this->retrieve_endpoint(cell_r))*2;
     
-    coordf_t w1 = cell1->contains_segment()
+    coordf_t w1 = cell_l->contains_segment()
-        ? line.b.perp_distance_to(segment1)*2
+        ? line.b.distance_to(segment_l)*2
-        : line.b.distance_to(this->retrieve_endpoint(cell1))*2;
+        : line.b.distance_to(this->retrieve_endpoint(cell_l))*2;
     
-    // if this edge is the centerline for a very thin area, we might want to skip it
+    if (cell_l->contains_segment() && cell_r->contains_segment()) {
-    // in case the area is too thin
-    if (w0 < SCALED_EPSILON || w1 < SCALED_EPSILON) {
-        if (cell1->contains_segment() && cell2->contains_segment()) {
         // calculate the relative angle between the two boundary segments
-            double angle = fabs(segment2.orientation() - segment1.orientation());
+        double angle = fabs(segment_r.orientation() - segment_l.orientation());
+        if (angle > PI) angle = 2*PI - angle;
+        assert(angle >= 0 && angle <= PI);
         
         // fabs(angle) ranges from 0 (collinear, same direction) to PI (collinear, opposite direction)
         // we're interested only in segments close to the second case (facing segments)
@@ -484,10 +494,17 @@ MedialAxis::validate_edge(const VD::edge_type* edge)
         // this filter ensures that we're dealing with a narrow/oriented area (longer than thick)
         // we don't run it on edges not generated by two segments (thus generated by one segment
         // and the endpoint of another segment), since their orientation would not be meaningful
-            if (fabs(angle - PI) > PI/5) return false;
+        if (PI - angle > PI/8) {
-        } else {
+            // angle is not narrow enough
+            
+            // only apply this filter to segments that are not too short otherwise their 
+            // angle could possibly be not meaningful
+            if (w0 < SCALED_EPSILON || w1 < SCALED_EPSILON || line.length() >= this->min_width)
                 return false;
         }
+    } else {
+        if (w0 < SCALED_EPSILON || w1 < SCALED_EPSILON)
+            return false;
     }
     
     if (w0 < this->min_width && w1 < this->min_width)

xs/src/libslic3r/Geometry.hpp

@@ -46,8 +46,8 @@ class MedialAxis {
     const ExPolygon* expolygon;
     double max_width;
     double min_width;
-    MedialAxis(double _max_width, double _min_width)
+    MedialAxis(double _max_width, double _min_width, const ExPolygon* _expolygon = NULL)
-        : max_width(_max_width), min_width(_min_width), expolygon(NULL) {};
+        : max_width(_max_width), min_width(_min_width), expolygon(_expolygon) {};
     void build(ThickPolylines* polylines);
     void build(Polylines* polylines);
     

xs/src/libslic3r/Line.cpp

@@ -212,6 +212,12 @@ Line::intersection(const Line& line, Point* intersection) const
     return false;  // not intersecting
 }
 
+double
+Line::ccw(const Point& point) const
+{
+    return point.ccw(*this);
+}
+
 Pointf3
 Linef3::intersect_plane(double z) const
 {

xs/src/libslic3r/Line.hpp

@@ -44,6 +44,7 @@ class Line
     void extend_end(double distance);
     void extend_start(double distance);
     bool intersection(const Line& line, Point* intersection) const;
+    double ccw(const Point& point) const;
 };
 
 class ThickLine : public Line

xs/src/libslic3r/MultiPoint.cpp

@@ -128,6 +128,19 @@ MultiPoint::intersection(const Line& line, Point* intersection) const
     return false;
 }
 
+std::string
+MultiPoint::dump_perl() const
+{
+    std::ostringstream ret;
+    ret << "[";
+    for (Points::const_iterator p = this->points.begin(); p != this->points.end(); ++p) {
+        ret << p->dump_perl();
+        if (p != this->points.end()-1) ret << ",";
+    }
+    ret << "]";
+    return ret.str();
+}
+
 Points
 MultiPoint::_douglas_peucker(const Points &points, const double tolerance)
 {

xs/src/libslic3r/MultiPoint.hpp

@@ -37,6 +37,7 @@ class MultiPoint
     void append(const Points &points);
     void append(const Points::const_iterator &begin, const Points::const_iterator &end);
     bool intersection(const Line& line, Point* intersection) const;
+    std::string dump_perl() const;
     
     static Points _douglas_peucker(const Points &points, const double tolerance);
 };

xs/src/libslic3r/PerimeterGenerator.cpp

@@ -92,7 +92,7 @@ PerimeterGenerator::process()
                         
                         // the following offset2 ensures almost nothing in @thin_walls is narrower than $min_width
                         // (actually, something larger than that still may exist due to mitering or other causes)
-                        coord_t min_width = scale_(this->ext_perimeter_flow.nozzle_diameter / 2);
+                        coord_t min_width = scale_(this->ext_perimeter_flow.nozzle_diameter / 3);
                         ExPolygons expp = offset2_ex(diffpp, -min_width/2, +min_width/2);
                         
                         // the maximum thickness of our thin wall area is equal to the minimum thickness of a single loop

xs/src/libslic3r/Point.cpp

@@ -26,6 +26,14 @@ Point::wkt() const
     return ss.str();
 }
 
+std::string
+Point::dump_perl() const
+{
+    std::ostringstream ss;
+    ss << "[" << this->x << "," << this->y << "]";
+    return ss.str();
+}
+
 void
 Point::scale(double factor)
 {
@@ -313,6 +321,14 @@ Pointf::wkt() const
     return ss.str();
 }
 
+std::string
+Pointf::dump_perl() const
+{
+    std::ostringstream ss;
+    ss << "[" << this->x << "," << this->y << "]";
+    return ss.str();
+}
+
 void
 Pointf::scale(double factor)
 {

xs/src/libslic3r/Point.hpp

@@ -38,6 +38,7 @@ class Point
     };
     bool operator==(const Point& rhs) const;
     std::string wkt() const;
+    std::string dump_perl() const;
     void scale(double factor);
     void translate(double x, double y);
     void translate(const Vector &vector);
@@ -87,6 +88,7 @@ class Pointf
         return Pointf(unscale(p.x), unscale(p.y));
     };
     std::string wkt() const;
+    std::string dump_perl() const;
     void scale(double factor);
     void translate(double x, double y);
     void translate(const Vectorf &vector);

xs/xsp/Line.xsp

@@ -41,6 +41,8 @@
         %code{% RETVAL = Polyline(*THIS); %};
     Clone<Point> normal();
     Clone<Point> vector();
+    double ccw(Point* point)
+        %code{% RETVAL = THIS->ccw(*point); %};
 %{
 
 Line*