Merge remote-tracking branch 'remotes/wavexx/gyroid_improvements' into gyroid_improvements

src/libslic3r/Fill/Fill3DHoneycomb.cpp

@@ -161,43 +161,38 @@ void Fill3DHoneycomb::_fill_surface_single(
     for (Polylines::iterator it = polylines.begin(); it != polylines.end(); ++ it)
         it->translate(bb.min(0), bb.min(1));
 
-    // clip pattern to boundaries
-    polylines = intersection_pl(polylines, (Polygons)expolygon);
+    // clip pattern to boundaries, keeping the polyline order & ordering the fragment to be able to join them easily
+    Polylines polylines_chained;
+    for (size_t idx_polyline = 0; idx_polyline < polylines.size(); ++idx_polyline) {
+        Polyline &poly_to_cut = polylines[idx_polyline];
+        Polylines polylines_to_sort = intersection_pl(Polylines() = { poly_to_cut }, (Polygons)expolygon);
+        for (Polyline &polyline : polylines_to_sort) {
+            //TODO: replace by closest_index_point()
+            if (poly_to_cut.points.front().distance_to_square(polyline.points.front()) > poly_to_cut.points.front().distance_to_square(polyline.points.back())) {
+                polyline.reverse();
+            }
+        }
+        if (polylines_to_sort.size() > 1) {
+            Point nearest = poly_to_cut.points.front();
+            //Bubble sort
+            for (size_t idx_sort = polylines_to_sort.size() - 1; idx_sort > 0; idx_sort--) {
+                for (size_t idx_bubble = 0; idx_bubble < idx_sort; idx_bubble++) {
+                    if (polylines_to_sort[idx_bubble + 1].points.front().distance_to_square(nearest) < polylines_to_sort[idx_bubble].points.front().distance_to_square(nearest)) {
+                        iter_swap(polylines_to_sort.begin() + idx_bubble, polylines_to_sort.begin() + idx_bubble + 1);
+                    }
+                }
+            }
+        }
+        polylines_chained.insert(polylines_chained.end(), polylines_to_sort.begin(), polylines_to_sort.end());
+    }
+    // connect lines if needed
+    if (!polylines_chained.empty()) {
+        if (params.dont_connect) {
+            polylines_out.insert(polylines_out.end(), polylines_chained.begin(), polylines_chained.end());
+        } else {
+            this->connect_infill(polylines_chained, expolygon, polylines_out, params);
+        }
 
-    // connect lines
-    if (! params.dont_connect && ! polylines.empty()) { // prevent calling leftmost_point() on empty collections
-        ExPolygon expolygon_off;
-        {
-            ExPolygons expolygons_off = offset_ex(expolygon, SCALED_EPSILON);
-            if (! expolygons_off.empty()) {
-                // When expanding a polygon, the number of islands could only shrink. Therefore the offset_ex shall generate exactly one expanded island for one input island.
-                assert(expolygons_off.size() == 1);
-                std::swap(expolygon_off, expolygons_off.front());
-            }
-        }
-        Polylines chained = PolylineCollection::chained_path_from(
-            std::move(polylines), 
-            PolylineCollection::leftmost_point(polylines), false); // reverse allowed
-        bool first = true;
-        for (Polylines::iterator it_polyline = chained.begin(); it_polyline != chained.end(); ++ it_polyline) {
-            if (! first) {
-                // Try to connect the lines.
-                Points &pts_end = polylines_out.back().points;
-                const Point &first_point = it_polyline->points.front();
-                const Point &last_point = pts_end.back();
-                // TODO: we should also check that both points are on a fill_boundary to avoid 
-                // connecting paths on the boundaries of internal regions
-                if ((last_point - first_point).cast<double>().norm() <= 1.5 * distance && 
-                    expolygon_off.contains(Line(last_point, first_point))) {
-                    // Append the polyline.
-                    pts_end.insert(pts_end.end(), it_polyline->points.begin(), it_polyline->points.end());
-                    continue;
-                }
-            }
-            // The lines cannot be connected.
-            polylines_out.emplace_back(std::move(*it_polyline));
-            first = false;
-        }
     }
 }
 

src/libslic3r/Fill/FillBase.cpp

@@ -130,4 +130,373 @@ std::pair<float, Point> Fill::_infill_direction(const Surface *surface) const
     return std::pair<float, Point>(out_angle, out_shift);
 }
 
+
+
+
+/// cut poly between poly.point[idx_1] & poly.point[idx_1+1]
+/// add p1+-width to one part and p2+-width to the other one.
+/// add the "new" polyline to polylines (to part cut from poly)
+/// p1 & p2 have to be between poly.point[idx_1] & poly.point[idx_1+1]
+/// if idx_1 is ==0 or == size-1, then we don't need to create a new polyline.
+void cut_polyline(Polyline &poly, Polylines &polylines, size_t idx_1, Point p1, Point p2) {
+    //reorder points
+    if (p1.distance_to_square(poly.points[idx_1]) > p2.distance_to_square(poly.points[idx_1])) {
+        Point temp = p2;
+        p2 = p1;
+        p1 = temp;
+    }
+    if (idx_1 == poly.points.size() - 1) {
+        //shouldn't be possible.
+        poly.points.erase(poly.points.end() - 1);
+    } else {
+        // create new polyline
+        Polyline new_poly;
+        //put points in new_poly
+        new_poly.points.push_back(p2);
+        new_poly.points.insert(new_poly.points.end(), poly.points.begin() + idx_1 + 1, poly.points.end());
+        //erase&put points in poly
+        poly.points.erase(poly.points.begin() + idx_1 + 1, poly.points.end());
+        poly.points.push_back(p1);
+        //safe test
+        if (poly.length() == 0)
+            poly.points = new_poly.points;
+        else
+            polylines.emplace_back(new_poly);
+    }
+}
+
+/// the poly is like a polygon but with first_point != last_point (already removed)
+void cut_polygon(Polyline &poly, size_t idx_1, Point p1, Point p2) {
+    //reorder points
+    if (p1.distance_to_square(poly.points[idx_1]) > p2.distance_to_square(poly.points[idx_1])) {
+        Point temp = p2;
+        p2 = p1;
+        p1 = temp;
+    }
+    //check if we need to rotate before cutting
+    if (idx_1 != poly.size() - 1) {
+        //put points in new_poly 
+        poly.points.insert(poly.points.end(), poly.points.begin(), poly.points.begin() + idx_1 + 1);
+        poly.points.erase(poly.points.begin(), poly.points.begin() + idx_1 + 1);
+    }
+    //put points in poly
+    poly.points.push_back(p1);
+    poly.points.insert(poly.points.begin(), p2);
+}
+
+/// check if the polyline from pts_to_check may be at 'width' distance of a point in polylines_blocker
+/// it use equally_spaced_points with width/2 precision, so don't worry with pts_to_check number of points.
+/// it use the given polylines_blocker points, be sure to put enough of them to be reliable.
+/// complexity : N(pts_to_check.equally_spaced_points(width / 2)) x N(polylines_blocker.points)
+bool collision(const Points &pts_to_check, const Polylines &polylines_blocker, const coordf_t width) {
+    //check if it's not too close to a polyline
+    coordf_t min_dist_square = width * width * 0.9 - SCALED_EPSILON;
+    Polyline better_polylines(pts_to_check);
+    Points better_pts = better_polylines.equally_spaced_points(width / 2);
+    for (const Point &p : better_pts) {
+        for (const Polyline &poly2 : polylines_blocker) {
+            for (const Point &p2 : poly2.points) {
+                if (p.distance_to_square(p2) < min_dist_square) {
+                    return true;
+                }
+            }
+        }
+    }
+    return false;
+}
+
+/// Try to find a path inside polylines that allow to go from p1 to p2.
+/// width if the width of the extrusion
+/// polylines_blockers are the array of polylines to check if the path isn't blocked by something.
+/// complexity: N(polylines.points) + a collision check after that if we finded a path: N(2(p2-p1)/width) x N(polylines_blocker.points)
+Points getFrontier(Polylines &polylines, const Point& p1, const Point& p2, const coord_t width, const Polylines &polylines_blockers, coord_t max_size = -1) {
+    for (size_t idx_poly = 0; idx_poly < polylines.size(); ++idx_poly) {
+        Polyline &poly = polylines[idx_poly];
+        if (poly.size() <= 1) continue;
+
+        //loop?
+        if (poly.first_point() == poly.last_point()) {
+            //polygon : try to find a line for p1 & p2.
+            size_t idx_11, idx_12, idx_21, idx_22;
+            idx_11 = poly.closest_point_index(p1);
+            idx_12 = idx_11;
+            if (Line(poly.points[idx_11], poly.points[(idx_11 + 1) % (poly.points.size() - 1)]).distance_to(p1) < SCALED_EPSILON) {
+                idx_12 = (idx_11 + 1) % (poly.points.size() - 1);
+            } else if (Line(poly.points[(idx_11 > 0) ? (idx_11 - 1) : (poly.points.size() - 2)], poly.points[idx_11]).distance_to(p1) < SCALED_EPSILON) {
+                idx_11 = (idx_11 > 0) ? (idx_11 - 1) : (poly.points.size() - 2);
+            } else {
+                continue;
+            }
+            idx_21 = poly.closest_point_index(p2);
+            idx_22 = idx_21;
+            if (Line(poly.points[idx_21], poly.points[(idx_21 + 1) % (poly.points.size() - 1)]).distance_to(p2) < SCALED_EPSILON) {
+                idx_22 = (idx_21 + 1) % (poly.points.size() - 1);
+            } else if (Line(poly.points[(idx_21 > 0) ? (idx_21 - 1) : (poly.points.size() - 2)], poly.points[idx_21]).distance_to(p2) < SCALED_EPSILON) {
+                idx_21 = (idx_21 > 0) ? (idx_21 - 1) : (poly.points.size() - 2);
+            } else {
+                continue;
+            }
+
+
+            //edge case: on the same line
+            if (idx_11 == idx_21 && idx_12 == idx_22) {
+                if (collision(Points() = { p1, p2 }, polylines_blockers, width)) return Points();
+                //break loop
+                poly.points.erase(poly.points.end() - 1);
+                cut_polygon(poly, idx_11, p1, p2);
+                return Points() = { Line(p1, p2).midpoint() };
+            }
+
+            //compute distance & array for the ++ path
+            Points ret_1_to_2;
+            double dist_1_to_2 = p1.distance_to(poly.points[idx_12]);
+            ret_1_to_2.push_back(poly.points[idx_12]);
+            size_t max = idx_12 <= idx_21 ? idx_21+1 : poly.points.size();
+            for (size_t i = idx_12 + 1; i < max; i++) {
+                dist_1_to_2 += poly.points[i - 1].distance_to(poly.points[i]);
+                ret_1_to_2.push_back(poly.points[i]);
+            }
+            if (idx_12 > idx_21) {
+                dist_1_to_2 += poly.points.back().distance_to(poly.points.front());
+                ret_1_to_2.push_back(poly.points[0]);
+                for (size_t i = 1; i <= idx_21; i++) {
+                    dist_1_to_2 += poly.points[i - 1].distance_to(poly.points[i]);
+                    ret_1_to_2.push_back(poly.points[i]);
+                }
+            }
+            dist_1_to_2 += p2.distance_to(poly.points[idx_21]);
+
+            //compute distance & array for the -- path
+            Points ret_2_to_1;
+            double dist_2_to_1 = p1.distance_to(poly.points[idx_11]);
+            ret_2_to_1.push_back(poly.points[idx_11]);
+            size_t min = idx_22 <= idx_11 ? idx_22 : 0;
+            for (size_t i = idx_11; i > min; i--) {
+                dist_2_to_1 += poly.points[i - 1].distance_to(poly.points[i]);
+                ret_2_to_1.push_back(poly.points[i - 1]);
+            }
+            if (idx_22 > idx_11) {
+                dist_2_to_1 += poly.points.back().distance_to(poly.points.front());
+                ret_2_to_1.push_back(poly.points[poly.points.size() - 1]);
+                for (size_t i = poly.points.size() - 1; i > idx_22; i--) {
+                    dist_2_to_1 += poly.points[i - 1].distance_to(poly.points[i]);
+                    ret_2_to_1.push_back(poly.points[i - 1]);
+                }
+            }
+            dist_2_to_1 += p2.distance_to(poly.points[idx_22]);
+
+            if (max_size < dist_2_to_1 && max_size < dist_1_to_2) {
+                return Points();
+            }
+
+            //choose between the two direction (keep the short one)
+            if (dist_1_to_2 < dist_2_to_1) {
+                if (collision(ret_1_to_2, polylines_blockers, width)) return Points();
+                //break loop
+                poly.points.erase(poly.points.end() - 1);
+                //remove points
+                if (idx_12 <= idx_21) {
+                    poly.points.erase(poly.points.begin() + idx_12, poly.points.begin() + idx_21 + 1);
+                    if (idx_12 != 0) {
+                        cut_polygon(poly, idx_11, p1, p2);
+                    } //else : already cut at the good place
+                } else {
+                    poly.points.erase(poly.points.begin() + idx_12, poly.points.end());
+                    poly.points.erase(poly.points.begin(), poly.points.begin() + idx_21);
+                    cut_polygon(poly, poly.points.size() - 1, p1, p2);
+                }
+                return ret_1_to_2;
+            } else {
+                if (collision(ret_2_to_1, polylines_blockers, width)) return Points();
+                //break loop
+                poly.points.erase(poly.points.end() - 1);
+                //remove points
+                if (idx_22 <= idx_11) {
+                    poly.points.erase(poly.points.begin() + idx_22, poly.points.begin() + idx_11 + 1);
+                    if (idx_22 != 0) {
+                        cut_polygon(poly, idx_21, p1, p2);
+                    } //else : already cut at the good place
+                } else {
+                    poly.points.erase(poly.points.begin() + idx_22, poly.points.end());
+                    poly.points.erase(poly.points.begin(), poly.points.begin() + idx_11);
+                    cut_polygon(poly, poly.points.size() - 1, p1, p2);
+                }
+                return ret_2_to_1;
+            }
+        } else {
+            //polyline : try to find a line for p1 & p2.
+            size_t idx_1, idx_2;
+            idx_1 = poly.closest_point_index(p1);
+            if (idx_1 < poly.points.size() - 1 && Line(poly.points[idx_1], poly.points[idx_1 + 1]).distance_to(p1) < SCALED_EPSILON) {
+            } else if (idx_1 > 0 && Line(poly.points[idx_1 - 1], poly.points[idx_1]).distance_to(p1) < SCALED_EPSILON) {
+                idx_1 = idx_1 - 1;
+            } else {
+                continue;
+            }
+            idx_2 = poly.closest_point_index(p2);
+            if (idx_2 < poly.points.size() - 1 && Line(poly.points[idx_2], poly.points[idx_2 + 1]).distance_to(p2) < SCALED_EPSILON) {
+            } else if (idx_2 > 0 && Line(poly.points[idx_2 - 1], poly.points[idx_2]).distance_to(p2) < SCALED_EPSILON) {
+                idx_2 = idx_2 - 1;
+            } else {
+                continue;
+            }
+
+            //edge case: on the same line
+            if (idx_1 == idx_2) {
+                if (collision(Points() = { p1, p2 }, polylines_blockers, width)) return Points();
+                cut_polyline(poly, polylines, idx_1, p1, p2);
+                return Points() = { Line(p1, p2).midpoint() };
+            }
+
+            //create ret array
+            size_t first_idx = idx_1;
+            size_t last_idx = idx_2 + 1;
+            if (idx_1 > idx_2) {
+                first_idx = idx_2;
+                last_idx = idx_1 + 1;
+            }
+            Points p_ret;
+            p_ret.insert(p_ret.end(), poly.points.begin() + first_idx + 1, poly.points.begin() + last_idx);
+
+            coordf_t length = 0;
+            for (size_t i = 1; i < p_ret.size(); i++) length += p_ret[i - 1].distance_to(p_ret[i]);
+
+            if (max_size < length) {
+                return Points();
+            }
+
+            if (collision(p_ret, polylines_blockers, width)) return Points();
+            //cut polyline
+            poly.points.erase(poly.points.begin() + first_idx + 1, poly.points.begin() + last_idx);
+            cut_polyline(poly, polylines, first_idx, p1, p2);
+            //order the returned array to be p1->p2
+            if (idx_1 > idx_2) {
+                std::reverse(p_ret.begin(), p_ret.end());
+            }
+            return p_ret;
+        }
+
+    }
+
+    return Points();
+}
+
+/// Connect the infill_ordered polylines, in this order, from the back point to the next front point.
+/// It uses only the boundary polygons to do so, and can't pass two times at the same place.
+/// It avoid passing over the infill_ordered's polylines (preventing local over-extrusion).
+/// return the connected polylines in polylines_out. Can output polygons (stored as polylines with first_point = last_point).
+/// complexity: worst: N(infill_ordered.points) x N(boundary.points)
+///             typical: N(infill_ordered) x ( N(boundary.points) + N(infill_ordered.points) )
+void Fill::connect_infill(const Polylines &infill_ordered, const ExPolygon &boundary, Polylines &polylines_out, const FillParams &params) {
+
+    //TODO: fallback to the quick & dirty old algorithm when n(points) is too high.
+    Polylines polylines_frontier = to_polylines(((Polygons)boundary));
+
+    Polylines polylines_blocker;
+    coord_t clip_size = scale_(this->spacing) * 2;
+    for (const Polyline &polyline : infill_ordered) {
+        if (polyline.length() > 2.01 * clip_size) {
+            polylines_blocker.push_back(polyline);
+            polylines_blocker.back().clip_end(clip_size);
+            polylines_blocker.back().clip_start(clip_size);
+        }
+    }
+
+    //length between two lines
+    coordf_t ideal_length = (1 / params.density) * this->spacing;
+
+    Polylines polylines_connected_first;
+    bool first = true;
+    for (const Polyline &polyline : infill_ordered) {
+        if (!first) {
+            // Try to connect the lines.
+            Points &pts_end = polylines_connected_first.back().points;
+            const Point &last_point = pts_end.back();
+            const Point &first_point = polyline.points.front();
+            if (last_point.distance_to(first_point) < scale_(this->spacing) * 10) {
+                Points pts_frontier = getFrontier(polylines_frontier, last_point, first_point, scale_(this->spacing), polylines_blocker, (coord_t)scale_(ideal_length) * 2);
+                if (!pts_frontier.empty()) {
+                    // The lines can be connected.
+                    pts_end.insert(pts_end.end(), pts_frontier.begin(), pts_frontier.end());
+                    pts_end.insert(pts_end.end(), polyline.points.begin(), polyline.points.end());
+                    continue;
+                }
+            }
+        }
+        // The lines cannot be connected.
+        polylines_connected_first.emplace_back(std::move(polyline));
+
+        first = false;
+    }
+
+    Polylines polylines_connected;
+    first = true;
+    for (const Polyline &polyline : polylines_connected_first) {
+        if (!first) {
+            // Try to connect the lines.
+            Points &pts_end = polylines_connected.back().points;
+            const Point &last_point = pts_end.back();
+            const Point &first_point = polyline.points.front();
+
+            Polylines before = polylines_frontier;
+            Points pts_frontier = getFrontier(polylines_frontier, last_point, first_point, scale_(this->spacing), polylines_blocker);
+            if (!pts_frontier.empty()) {
+                // The lines can be connected.
+                pts_end.insert(pts_end.end(), pts_frontier.begin(), pts_frontier.end());
+                pts_end.insert(pts_end.end(), polyline.points.begin(), polyline.points.end());
+                continue;
+            }
+        }
+        // The lines cannot be connected.
+        polylines_connected.emplace_back(std::move(polyline));
+
+        first = false;
+    }
+
+    //try to link to nearest point if possible
+    for (size_t idx1 = 0; idx1 < polylines_connected.size(); idx1++) {
+        size_t min_idx = 0;
+        coordf_t min_length = 0;
+        bool switch_id1 = false;
+        bool switch_id2 = false;
+        for (size_t idx2 = idx1 + 1; idx2 < polylines_connected.size(); idx2++) {
+            double last_first = polylines_connected[idx1].last_point().distance_to_square(polylines_connected[idx2].first_point());
+            double first_first = polylines_connected[idx1].first_point().distance_to_square(polylines_connected[idx2].first_point());
+            double first_last = polylines_connected[idx1].first_point().distance_to_square(polylines_connected[idx2].last_point());
+            double last_last = polylines_connected[idx1].last_point().distance_to_square(polylines_connected[idx2].last_point());
+            double min = std::min(std::min(last_first, last_last), std::min(first_first, first_last));
+            if (min < min_length || min_length == 0) {
+                min_idx = idx2;
+                switch_id1 = (std::min(last_first, last_last) > std::min(first_first, first_last));
+                switch_id2 = (std::min(last_first, first_first) > std::min(last_last, first_last));
+                min_length = min;
+            }
+        }
+        if (min_idx > idx1 && min_idx < polylines_connected.size()){
+            Points pts_frontier = getFrontier(polylines_frontier, 
+                switch_id1 ? polylines_connected[idx1].first_point() : polylines_connected[idx1].last_point(), 
+                switch_id2 ? polylines_connected[min_idx].last_point() : polylines_connected[min_idx].first_point(),
+                scale_(this->spacing), polylines_blocker);
+            if (!pts_frontier.empty()) {
+                if (switch_id1) polylines_connected[idx1].reverse();
+                if (switch_id2) polylines_connected[min_idx].reverse();
+                Points &pts_end = polylines_connected[idx1].points;
+                pts_end.insert(pts_end.end(), pts_frontier.begin(), pts_frontier.end());
+                pts_end.insert(pts_end.end(), polylines_connected[min_idx].points.begin(), polylines_connected[min_idx].points.end());
+                polylines_connected.erase(polylines_connected.begin() + min_idx);
+            }
+        }
+    }
+
+    //try to create some loops if possible
+    for (Polyline &polyline : polylines_connected) {
+        Points pts_frontier = getFrontier(polylines_frontier, polyline.last_point(), polyline.first_point(), scale_(this->spacing), polylines_blocker);
+        if (!pts_frontier.empty()) {
+            polyline.points.insert(polyline.points.end(), pts_frontier.begin(), pts_frontier.end());
+            polyline.points.insert(polyline.points.begin(), polyline.points.back());
+        }
+        polylines_out.emplace_back(polyline);
+    }
+}
+
 } // namespace Slic3r

src/libslic3r/Fill/FillBase.hpp

@@ -109,6 +109,8 @@ protected:
 
     virtual std::pair<float, Point> _infill_direction(const Surface *surface) const;
 
+    void connect_infill(const Polylines &infill_ordered, const ExPolygon &boundary, Polylines &polylines_out, const FillParams &params);
+
 public:
     static coord_t  _adjust_solid_spacing(const coord_t width, const coord_t distance);
 

src/libslic3r/Fill/FillGyroid.cpp

@@ -31,19 +31,26 @@ static inline double f(double x, double z_sin, double z_cos, bool vertical, bool
 
 static inline Polyline make_wave(
     const std::vector<Vec2d>& one_period, double width, double height, double offset, double scaleFactor,
-    double z_cos, double z_sin, bool vertical)
+    double z_cos, double z_sin, bool vertical, bool flip)
 {
     std::vector<Vec2d> points = one_period;
     double period = points.back()(0);
+    if (width != period) // do not extend if already truncated
+    {
+        points.reserve(one_period.size() * floor(width / period));
         points.pop_back();
+
         int n = points.size();
         do {
             points.emplace_back(Vec2d(points[points.size()-n](0) + period, points[points.size()-n](1)));
-    } while (points.back()(0) < width);
-    points.back()(0) = width;
+        } while (points.back()(0) < width - EPSILON);
+
+        points.emplace_back(Vec2d(width, f(width, z_sin, z_cos, vertical, flip)));
+    }
 
     // and construct the final polyline to return:
     Polyline polyline;
+    polyline.points.reserve(points.size());
     for (auto& point : points) {
         point(1) += offset;
         point(1) = clamp(0., height, double(point(1)));
@@ -55,43 +62,54 @@ static inline Polyline make_wave(
     return polyline;
 }
 
-static std::vector<Vec2d> make_one_period(double width, double scaleFactor, double z_cos, double z_sin, bool vertical, bool flip)
+static std::vector<Vec2d> make_one_period(double width, double scaleFactor, double z_cos, double z_sin, bool vertical, bool flip, double tolerance)
 {
     std::vector<Vec2d> points;
-    double dx = M_PI_4; // very coarse spacing to begin with
+    double dx = M_PI_2; // exact coordinates on main inflexion lobes
     double limit = std::min(2*M_PI, width);
-    for (double x = 0.; x < limit + EPSILON; x += dx) {  // so the last point is there too
-        x = std::min(x, limit);
-        points.emplace_back(Vec2d(x,f(x, z_sin,z_cos, vertical, flip)));
+    points.reserve(ceil(limit / tolerance / 3));
+
+    for (double x = 0.; x < limit - EPSILON; x += dx) {
+        points.emplace_back(Vec2d(x, f(x, z_sin, z_cos, vertical, flip)));
+    }
+    points.emplace_back(Vec2d(limit, f(limit, z_sin, z_cos, vertical, flip)));
+
+    // piecewise increase in resolution up to requested tolerance
+    for(;;)
+    {
+        size_t size = points.size();
+        for (unsigned int i = 1;i < size; ++i) {
+            auto& lp = points[i-1]; // left point
+            auto& rp = points[i];   // right point
+            double x = lp(0) + (rp(0) - lp(0)) / 2;
+            double y = f(x, z_sin, z_cos, vertical, flip);
+            Vec2d ip = {x, y};
+            if (std::abs(cross2(Vec2d(ip - lp), Vec2d(ip - rp))) > sqr(tolerance)) {
+                points.emplace_back(std::move(ip));
+            }
         }
 
-    // now we will check all internal points and in case some are too far from the line connecting its neighbours,
-    // we will add one more point on each side:
-    const double tolerance = .1;
-    for (unsigned int i=1;i<points.size()-1;++i) {
-        auto& lp = points[i-1]; // left point
-        auto& tp = points[i];   // this point
-        Vec2d lrv = tp - lp;
-        auto& rp = points[i+1]; // right point
-        // calculate distance of the point to the line:
-        double dist_mm = unscale<double>(scaleFactor) * std::abs(cross2(rp, lp) - cross2(rp - lp, tp)) / lrv.norm();
-        if (dist_mm > tolerance) {                               // if the difference from straight line is more than this
-            double x = 0.5f * (points[i-1](0) + points[i](0));
-            points.emplace_back(Vec2d(x, f(x, z_sin, z_cos, vertical, flip)));
-            x = 0.5f * (points[i+1](0) + points[i](0));
-            points.emplace_back(Vec2d(x, f(x, z_sin, z_cos, vertical, flip)));
-            // we added the points to the end, but need them all in order
-            std::sort(points.begin(), points.end(), [](const Vec2d &lhs, const Vec2d &rhs){ return lhs < rhs; });
-            // decrement i so we also check the first newly added point
-            --i;
+        if (size == points.size())
+            break;
+        else
+        {
+            // insert new points in order
+            std::sort(points.begin(), points.end(),
+                      [](const Vec2d &lhs, const Vec2d &rhs) { return lhs(0) < rhs(0); });
         }
     }
+
     return points;
 }
 
 static Polylines make_gyroid_waves(double gridZ, double density_adjusted, double line_spacing, double width, double height)
 {
     const double scaleFactor = scale_(line_spacing) / density_adjusted;
+
+    // tolerance in scaled units. clamp the maximum tolerance as there's
+    // no processing-speed benefit to do so beyond a certain point
+    const double tolerance = std::min(line_spacing / 2, FillGyroid::PatternTolerance) / unscale<double>(scaleFactor);
+
     //scale factor for 5% : 8 712 388
     // 1z = 10^-6 mm ?
     const double z     = gridZ / scaleFactor;
@@ -109,16 +127,20 @@ static Polylines make_gyroid_waves(double gridZ, double density_adjusted, double
         std::swap(width,height);
     }
 
-    std::vector<Vec2d> one_period = make_one_period(width, scaleFactor, z_cos, z_sin, vertical, flip); // creates one period of the waves, so it doesn't have to be recalculated all the time
+    std::vector<Vec2d> one_period_odd = make_one_period(width, scaleFactor, z_cos, z_sin, vertical, flip, tolerance); // creates one period of the waves, so it doesn't have to be recalculated all the time
+    flip = !flip;                                                                   // even polylines are a bit shifted
+    std::vector<Vec2d> one_period_even = make_one_period(width, scaleFactor, z_cos, z_sin, vertical, flip, tolerance);
     Polylines result;
 
-    for (double y0 = lower_bound; y0 < upper_bound+EPSILON; y0 += 2*M_PI)           // creates odd polylines
-            result.emplace_back(make_wave(one_period, width, height, y0, scaleFactor, z_cos, z_sin, vertical));
-
-    flip = !flip;                                                                   // even polylines are a bit shifted
-    one_period = make_one_period(width, scaleFactor, z_cos, z_sin, vertical, flip); // updates the one period sample
-    for (double y0 = lower_bound + M_PI; y0 < upper_bound+EPSILON; y0 += 2*M_PI)    // creates even polylines
-            result.emplace_back(make_wave(one_period, width, height, y0, scaleFactor, z_cos, z_sin, vertical));
+    for (double y0 = lower_bound; y0 < upper_bound + EPSILON; y0 += M_PI) {
+        // creates odd polylines
+        result.emplace_back(make_wave(one_period_odd, width, height, y0, scaleFactor, z_cos, z_sin, vertical, flip));
+        // creates even polylines
+        y0 += M_PI;
+        if (y0 < upper_bound + EPSILON) {
+            result.emplace_back(make_wave(one_period_even, width, height, y0, scaleFactor, z_cos, z_sin, vertical, flip));
+        }
+    }
 
     return result;
 }
@@ -130,65 +152,88 @@ void FillGyroid::_fill_surface_single(
     ExPolygon                       &expolygon, 
     Polylines                       &polylines_out)
 {
-    // no rotation is supported for this infill pattern (yet)
+    float infill_angle = this->angle + (CorrectionAngle * 2*M_PI) / 360.;
+    if(abs(infill_angle) >= EPSILON)
+        expolygon.rotate(-infill_angle);
+
     BoundingBox bb = expolygon.contour.bounding_box();
     // Density adjusted to have a good %of weight.
-    double      density_adjusted = std::max(0., params.density * 2.44);
+    double      density_adjusted = std::max(0., params.density * DensityAdjust);
     // Distance between the gyroid waves in scaled coordinates.
     coord_t     distance = coord_t(scale_(this->spacing) / density_adjusted);
 
     // align bounding box to a multiple of our grid module
-    bb.merge(_align_to_grid(bb.min, Point(2.*M_PI*distance, 2.*M_PI*distance)));
+    bb.merge(_align_to_grid(bb.min, Point(2*M_PI*distance, 2*M_PI*distance)));
 
     // generate pattern
-    Polylines   polylines = make_gyroid_waves(
+    Polylines polylines_square = make_gyroid_waves(
         scale_(this->z),
         density_adjusted,
         this->spacing,
         ceil(bb.size()(0) / distance) + 1.,
         ceil(bb.size()(1) / distance) + 1.);
 
-    // move pattern in place
-    for (Polyline &polyline : polylines)
-        polyline.translate(bb.min(0), bb.min(1));
+    // clip pattern to boundaries, keeping the polyline order & ordering the fragment to be able to join them easily
+    Polylines polylines_chained;
+    for (size_t idx_polyline = 0; idx_polyline < polylines_square.size(); ++idx_polyline) {
+        // shift the polyline to the grid origin
+        Polyline &poly_to_cut = polylines_square[idx_polyline];
+        poly_to_cut.translate(bb.min);
 
-    // clip pattern to boundaries
-    polylines = intersection_pl(polylines, (Polygons)expolygon);
+        // intersect
+        Polylines polylines_to_sort = intersection_pl(Polylines() = { poly_to_cut }, (Polygons)expolygon);
+        for (Polyline &polyline : polylines_to_sort) {
+            //TODO: replace by closest_index_point()
+            if (idx_polyline % 2 == 0) {
+                if (poly_to_cut.points.front().distance_to_square(polyline.points.front()) > poly_to_cut.points.front().distance_to_square(polyline.points.back())) {
+                    polyline.reverse();
+                }
+            } else {
+                if (poly_to_cut.points.back().distance_to_square(polyline.points.front()) > poly_to_cut.points.back().distance_to_square(polyline.points.back())) {
+                    polyline.reverse();
+                }
+            }
+        }
+        if (polylines_to_sort.size() > 1) {
+            Point nearest = poly_to_cut.points.front();
+            if (idx_polyline % 2 != 0) {
+                nearest = poly_to_cut.points.back();
+            }
+            //Bubble sort
+            for (size_t idx_sort = polylines_to_sort.size() - 1; idx_sort > 0; idx_sort--) {
+                for (size_t idx_bubble = 0; idx_bubble < idx_sort; idx_bubble++) {
+                    if (polylines_to_sort[idx_bubble + 1].points.front().distance_to_square(nearest) < polylines_to_sort[idx_bubble].points.front().distance_to_square(nearest)) {
+                        iter_swap(polylines_to_sort.begin() + idx_bubble, polylines_to_sort.begin() + idx_bubble + 1);
+                    }
+                }
+            }
+        }
+        polylines_chained.insert(polylines_chained.end(), polylines_to_sort.begin(), polylines_to_sort.end());
+    }
 
+    size_t polylines_out_first_idx = polylines_out.size();
+    if (!polylines_chained.empty()) {
         // connect lines
-    if (! params.dont_connect && ! polylines.empty()) { // prevent calling leftmost_point() on empty collections
-        ExPolygon expolygon_off;
-        {
-            ExPolygons expolygons_off = offset_ex(expolygon, (float)SCALED_EPSILON);
-            if (! expolygons_off.empty()) {
-                // When expanding a polygon, the number of islands could only shrink. Therefore the offset_ex shall generate exactly one expanded island for one input island.
-                assert(expolygons_off.size() == 1);
-                std::swap(expolygon_off, expolygons_off.front());
+        if (params.dont_connect) {
+            polylines_out.insert(polylines_out.end(), polylines_chained.begin(), polylines_chained.end());
+        } else {
+            this->connect_infill(polylines_chained, expolygon, polylines_out, params);
         }
     }
-        Polylines chained = PolylineCollection::chained_path_from(
-            std::move(polylines), 
-            PolylineCollection::leftmost_point(polylines), false); // reverse allowed
-        bool first = true;
-        for (Polyline &polyline : chained) {
-            if (! first) {
-                // Try to connect the lines.
-                Points &pts_end = polylines_out.back().points;
-                const Point &first_point = polyline.points.front();
-                const Point &last_point = pts_end.back();
-                // TODO: we should also check that both points are on a fill_boundary to avoid 
-                // connecting paths on the boundaries of internal regions
-                // TODO: avoid crossing current infill path
-                if ((last_point - first_point).cast<double>().norm() <= 5 * distance && 
-                    expolygon_off.contains(Line(last_point, first_point))) {
-                    // Append the polyline.
-                    pts_end.insert(pts_end.end(), polyline.points.begin(), polyline.points.end());
-                    continue;
+
+    //remove too small bits (larger than longer);
+    for (size_t idx = polylines_out_first_idx; idx < polylines_out.size(); idx++) {
+        if (polylines_out[idx].length() < scale_(this->spacing * 3)) {
+            polylines_out.erase(polylines_out.begin() + idx);
+            idx--;
         }
     }
-            // The lines cannot be connected.
-            polylines_out.emplace_back(std::move(polyline));
-            first = false;
+
+    // new paths must be rotated back
+    if(abs(infill_angle) >= EPSILON) {
+        for (Polylines::iterator it = polylines_out.begin() + polylines_out_first_idx;
+             it != polylines_out.end(); ++it) {
+            it->rotate(infill_angle);
         }
     }
 }

src/libslic3r/Fill/FillGyroid.hpp

@@ -16,6 +16,17 @@ public:
     // require bridge flow since most of this pattern hangs in air
     virtual bool use_bridge_flow() const { return false; }
 
+    // Correction applied to regular infill angle to maximize printing
+    // speed in default configuration (degrees)
+    static constexpr float CorrectionAngle = -45.;
+
+    // Density adjustment to have a good %of weight.
+    static constexpr double DensityAdjust = 2.44;
+
+    // Gyroid upper resolution tolerance (mm^-2)
+    static constexpr double PatternTolerance = 0.2;
+
+
 protected:
     virtual void _fill_surface_single(
         const FillParams                &params, 

src/libslic3r/Point.hpp

@@ -124,6 +124,13 @@ public:
     double ccw_angle(const Point &p1, const Point &p2) const;
     Point  projection_onto(const MultiPoint &poly) const;
     Point  projection_onto(const Line &line) const;
+
+    double distance_to(const Point &point) const { return (point - *this).cast<double>().norm(); }
+    double distance_to_square(const Point &point) const {
+        double dx = (point.x() - this->x());
+        double dy = (point.y() - this->y());
+        return dx*dx + dy*dy;
+    }
 };
 
 namespace int128 {