Fix sampling selfconnected thiny part of island sampled on voronoi skelet

src/libslic3r/SLA/SupportIslands/SampleConfigFactory.hpp

@@ -1,6 +1,7 @@
 #ifndef slic3r_SLA_SuppotstIslands_SampleConfigFactory_hpp_
 #define slic3r_SLA_SuppotstIslands_SampleConfigFactory_hpp_
 
+#include "SampleConfig.hpp"
 #include "../SupportPointGenerator.hpp"
 
 namespace Slic3r::sla {
@@ -14,16 +15,16 @@ public:
     SampleConfigFactory() = delete;
 
     // factory method to iniciate config
-    static SampleConfig create(const SupportPointGenerator::Config &config)
+    static SampleConfig create(const SupportPointGeneratorConfig &config)
     {
-        coord_t head_diameter = scale_(config.head_diameter);
+        coord_t head_diameter = scale_((double)config.head_diameter.min);
-        coord_t min_distance = head_diameter/2 + scale_(config.minimal_distance);
+        coord_t minimal_distance = head_diameter * 7;
-        coord_t max_distance  = 3 * min_distance;
+        coord_t min_distance = head_diameter / 2 + minimal_distance;
-        coord_t sample_multiplicator = 8; // allign is made by selecting from samples
+        coord_t max_distance = 3 * min_distance;
-
+        
         // TODO: find valid params !!!!
         SampleConfig result;
-        result.max_distance                  = max_distance / sample_multiplicator;
+        result.max_distance                  = max_distance;
         result.half_distance                 = result.max_distance / 2;
         result.head_radius                   = head_diameter / 2;
         result.minimal_distance_from_outline = result.head_radius;
@@ -73,7 +74,7 @@ public:
         result.min_width_for_outline_support = result.max_width_for_center_support_line - 2 * head_diameter;
         assert(result.min_width_for_outline_support <= result.max_width_for_center_support_line);
 
-        result.outline_sample_distance = result.max_distance/20;
+        result.outline_sample_distance = result.max_distance/4;
 
         // Align support points
         // TODO: propagate print resolution

src/libslic3r/SLA/SupportIslands/SampleIslandUtils.cpp

@@ -23,14 +23,61 @@
 //#define SLA_SAMPLE_ISLAND_UTILS_STORE_VORONOI_GRAPH_TO_SVG
 //#define SLA_SAMPLE_ISLAND_UTILS_STORE_INITIAL_SAMPLE_POSITION_TO_SVG
 //#define SLA_SAMPLE_ISLAND_UTILS_STORE_FIELD_TO_SVG
-//#define SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGNE_VD_TO_SVG
-//#define SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
 //#define SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGNED_TO_SVG
 
+//#define SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH "C:/data/temp/Align_once_<<COUNTER>>.svg"
+//#define SLA_SAMPLE_ISLAND_UTILS_DEBUG_CELL_DISTANCE_PATH "C:/data/temp/island_cell.svg"
+
 #include <cassert>
 
+using namespace Slic3r;
 using namespace Slic3r::sla;
 
+namespace {
+const ExPolygon &get_expolygon_with_biggest_contour(const ExPolygons &expolygons) {
+    assert(!expolygons.empty());
+    const ExPolygon *biggest = &expolygons.front();
+    for (size_t index = 1; index < expolygons.size(); ++index) {
+        const ExPolygon *current = &expolygons[index];
+        if (biggest->contour.size() < current->contour.size())
+            biggest = current;
+    }
+    return *biggest;
+}
+} // namespace
+
+SupportIslandPoints SampleIslandUtils::uniform_cover_island(
+    const ExPolygon &island, const SampleConfig &config
+) {
+    // closing similar to FDM arachne do before voronoi
+    // inspired by make_expolygons inside TriangleMeshSlicer
+    float closing_radius = scale_(0.0499f);
+    float offset_out = closing_radius;
+    float offset_in = -closing_radius;
+    ExPolygons closed_expolygons = offset2_ex({island}, offset_out, offset_in); // mitter
+    ExPolygon closed_expolygon = get_expolygon_with_biggest_contour(closed_expolygons);
+
+    // "Close" operation create neighbor pixel for sharp triangle tip
+    double tolerance = scale_(0.05);
+    ExPolygons simplified_expolygons = island.simplify(tolerance);
+    ExPolygon simplified_expolygon = get_expolygon_with_biggest_contour(simplified_expolygons);
+
+    Slic3r::Geometry::VoronoiDiagram vd;
+    Lines lines = to_lines(simplified_expolygon);
+    vd.construct_voronoi(lines.begin(), lines.end());
+    Slic3r::Voronoi::annotate_inside_outside(vd, lines);
+    VoronoiGraph skeleton = VoronoiGraphUtils::create_skeleton(vd, lines);
+    VoronoiGraph::ExPath longest_path;
+    
+    SupportIslandPoints samples =
+        SampleIslandUtils::sample_voronoi_graph(skeleton, lines, config, longest_path);
+
+    // allign samples
+    SampleIslandUtils::align_samples(samples, island, config);
+
+    return samples;
+}
+
 std::vector<Slic3r::Vec2f> SampleIslandUtils::sample_expolygon(
     const ExPolygon &expoly, float samples_per_mm2)
 {
@@ -440,115 +487,145 @@ void SampleIslandUtils::align_samples(SupportIslandPoints &samples,
     
 }
 
+namespace {
+Polygons create_voronoi_cells_boost(const Points &points, coord_t max_distance) {
+    using VD = Slic3r::Geometry::VoronoiDiagram;
+    VD vd;
+    vd.construct_voronoi(points.begin(), points.end());
+    assert(points.size() == vd.cells().size());
+    Polygons cells(points.size());
+    for (const VD::cell_type &cell : vd.cells())
+        cells[cell.source_index()] = VoronoiGraphUtils::to_polygon(cell, points, max_distance);
+    return cells;
+}
+
+std::string replace_first(
+    std::string s,
+    const std::string& toReplace,
+    const std::string& replaceWith
+) {
+    std::size_t pos = s.find(toReplace);
+    if (pos == std::string::npos) return s;
+    s.replace(pos, toReplace.length(), replaceWith);
+    return s;
+}
+
 bool is_points_in_distance(const Slic3r::Point & p,
                            const Slic3r::Points &points,
                            double                max_distance)
 {
     for (const auto &p2 : points) {
         double d = (p - p2).cast<double>().norm();
-        if (d > max_distance) return false;
+        if (d > max_distance)
+            return false;
     }
     return true;
 }
+} // namespace
 
-coord_t SampleIslandUtils::align_once(SupportIslandPoints &samples,
+coord_t SampleIslandUtils::align_once(
-                                      const ExPolygon &    island,
+    SupportIslandPoints &samples, 
-                                      const SampleConfig & config)
+    const ExPolygon &island, 
-{
+    const SampleConfig &config) 
-    using VD = Slic3r::Geometry::VoronoiDiagram;
+{  
-    VD             vd;
+    // IMPROVE1: add accessor to point coordinate do not copy points
+    // IMPROVE2: add filter for create cell polygon only for moveable samples
     Slic3r::Points points = SampleIslandUtils::to_points(samples);
-    coord_t max_move = 0;
-
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
-    std::string color_of_island = "#FF8080"; // LightRed. Should not be visible - cell color should overlap
-    std::string color_point_cell = "lightgray"; // bigger than island but NOT self overlap
-    std::string color_island_cell_intersection = "gray"; // Should full overlap island !!
-    std::string color_old_point = "lightblue"; // Center of island cell intersection
-    std::string color_wanted_point = "darkblue"; // Center of island cell intersection
-    std::string color_new_point = "blue"; // Center of island cell intersection
-    std::string color_static_point = "black";
-    static int  counter = 0;
-    BoundingBox bbox(island.contour.points);
     
-    SVG svg(("align_" + std::to_string(counter++) + ".svg").c_str(), bbox);
+    Polygons cell_polygons = //* 
-    svg.draw(island, color_of_island );
+        create_voronoi_cells_boost
-#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+    /*/
+        create_voronoi_cells_cgal
+    //*/
+    (points, config.max_distance);
+    
+#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
+    std::string color_of_island = "#FF8080";             // LightRed. Should not be visible - cell color should overlap
+    std::string color_point_cell = "lightgray";          // bigger than island but NOT self overlap
+    std::string color_island_cell_intersection = "gray"; // Should full overlap island !!
+    std::string color_old_point = "lightblue";           // Center of island cell intersection
+    std::string color_wanted_point = "darkblue";         // Center of island cell intersection
+    std::string color_new_point = "blue";                // Center of island cell intersection
+    std::string color_static_point = "black";
+    BoundingBox bbox(island.contour.points);
+    static int counter = 0;
+    Slic3r::SVG svg(replace_first(SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH, 
+        "<<COUNTER>>", std::to_string(counter++)).c_str(), bbox);
+    svg.draw(island, color_of_island);
+#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
 
-    // create voronoi diagram with points
+    // Maximal move during align each loop of align it should decrease
-    vd.construct_voronoi(points.begin(), points.end());
+    coord_t max_move = 0;
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGNE_VD_TO_SVG
+    for (size_t i = 0; i < points.size(); i++) {
-    static int vd_counter = 0;
+        const Polygon &cell_polygon = cell_polygons[i];
-    BoundingBox bbox(island);
+        SupportIslandPointPtr &sample = samples[i];
-    std::string name = "align_VD_" + std::to_string(vd_counter++) + ".svg";
-    SVG svg(name.c_str(), bbox);
-    svg.draw(island);
-    for (const Point &point : points) {
-        size_t index = &point - &points.front();
-        svg.draw(point, "black", config.head_radius);
-        svg.draw_text(point + Point(config.head_radius,0), std::to_string(index).c_str(), "black");
-    }
-    Lines island_lines = to_lines(island);
-    svg.draw(island_lines, "blue");
-    for (const auto &edge: vd.edges()) {
-        std::optional<Line> line =
-            VoronoiGraphUtils::to_line(edge, points, config.max_distance);
-        if (!line.has_value()) continue;
-        svg.draw(*line, "green", 1e6);
-    }
-    svg.Close();
-#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGNE_VD_TO_SVG
-    size_t max_move_index = -1;
-    for (const VD::cell_type &cell : vd.cells()) {
-        SupportIslandPointPtr &sample = samples[cell.source_index()];
 
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
-        if (!sample->can_move()) {
+        if (!sample->can_move()) { // draww freezed support points
             svg.draw(sample->point, color_static_point, config.head_radius);
-            svg.draw_text(sample->point+Point(config.head_radius,0), SupportIslandPoint::to_string(sample->type).c_str(), color_static_point.c_str());
+            svg.draw_text(sample->point + Point(config.head_radius, 0),
+                SupportIslandPoint::to_string(sample->type).c_str(), color_static_point.c_str());
         }
-#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
-        if (!sample->can_move()) continue;
+        if (!sample->can_move())
-        Polygon cell_polygon = VoronoiGraphUtils::to_polygon(cell, points, config.max_distance);
+            continue;
+        
+        // polygon must be at least triangle
+        assert(cell_polygon.points.size() >= 3);
+        if (cell_polygon.points.size() < 3)
+            continue; // do not align point with invalid cell
+
+        // IMPROVE: add intersection polygon with expolygon
         Polygons intersections = Slic3r::intersection(island, ExPolygon(cell_polygon));
-        const Polygon *island_cell   = nullptr;
+        const Polygon *island_cell = nullptr;
         for (const Polygon &intersection : intersections) {
             if (intersection.contains(sample->point)) {
                 island_cell = &intersection;
                 break;
             }
         }
-        assert(island_cell != nullptr);        
+
-        Point center = island_cell->centroid();        
+        // intersection island and cell made by suppot point 
-        /*{
+        // must generate polygon containing initial source for voronoi cell
-            SVG cell_svg("island_cell.svg", island_cell->points);
+        // otherwise it is invalid voronoi diagram
-            cell_svg.draw(cell_polygon, "lightgray");
+        assert(island_cell != nullptr);
-            cell_svg.draw(points, "darkgray", config.head_radius);
+        if (island_cell == nullptr)
-            cell_svg.draw(*island_cell, "gray");
+            continue;
-            cell_svg.draw(sample->point, "green", config.head_radius);
+
-            cell_svg.draw(center, "black", config.head_radius);
+        // new aligned position for sample
-        }*/
+        Point island_cell_center = island_cell->centroid();
-        assert(is_points_in_distance(center, island_cell->points, config.max_distance));
+
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+#ifdef SLA_SAMPLE_ISLAND_UTILS_DEBUG_CELL_DISTANCE_PATH
+        {SVG cell_svg(SLA_SAMPLE_ISLAND_UTILS_DEBUG_CELL_DISTANCE_PATH, island_cell->points);
+        cell_svg.draw(island, "lightgreen");
+        cell_svg.draw(cell_polygon, "lightgray");
+        cell_svg.draw(points, "darkgray", config.head_radius);
+        cell_svg.draw(*island_cell, "gray");
+        cell_svg.draw(sample->point, "green", config.head_radius);
+        cell_svg.draw(island_cell_center, "black", config.head_radius);}
+#endif //SLA_SAMPLE_ISLAND_UTILS_DEBUG_CELL_DISTANCE_PATH
+        // Check that still points do not have bigger distance from each other
+        assert(is_points_in_distance(island_cell_center, island_cell->points, config.max_distance));
+
+#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
         svg.draw(cell_polygon, color_point_cell);
         svg.draw(*island_cell, color_island_cell_intersection);
-        svg.draw(Line(sample->point, center), color_wanted_point, config.head_radius / 5);
+        svg.draw(Line(sample->point, island_cell_center), color_wanted_point, config.head_radius / 5);
         svg.draw(sample->point, color_old_point, config.head_radius);
-        svg.draw(center, color_wanted_point, config.head_radius); // wanted position
+        svg.draw(island_cell_center, color_wanted_point, config.head_radius); // wanted position
-#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
-        coord_t act_move = sample->move(center);
+
-        if (max_move < act_move) {
+        // say samples to use its restriction to change posion close to center
-            max_move = act_move; 
+        coord_t act_move = sample->move(island_cell_center);
-            max_move_index = cell.source_index();
+        if (max_move < act_move)
-        }
+            max_move = act_move;  
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+
-        svg.draw(sample->point, color_new_point, config.head_radius);        
+#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
-        svg.draw_text(sample->point+Point(config.head_radius,0), SupportIslandPoint::to_string(sample->type).c_str(), color_new_point.c_str());
+        svg.draw(sample->point, color_new_point, config.head_radius);
-#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+        svg.draw_text(sample->point + Point(config.head_radius, 0),
+            SupportIslandPoint::to_string(sample->type).c_str(), color_new_point.c_str());
+#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
     }
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
-    svg.Close();
-#endif // SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
     return max_move;
 }
 
@@ -897,6 +974,7 @@ SupportIslandPoints SampleIslandUtils::sample_voronoi_graph(
         SVG svg("voronoiGraph" + std::to_string(counter++) + ".svg",
                 LineUtils::create_bounding_box(lines));
         VoronoiGraphUtils::draw(svg, graph, lines, config.head_radius / 10, true);
+        VoronoiGraphUtils::draw(svg, longest_path, config.head_radius / 10);
     }
 #endif // SLA_SAMPLE_ISLAND_UTILS_STORE_VORONOI_GRAPH_TO_SVG
 
@@ -1031,6 +1109,83 @@ void SampleIslandUtils::sample_field(const VoronoiGraph::Position &field_start,
         });
 }
 
+namespace {
+bool pop_start(
+    SampleIslandUtils::CenterStart &start,
+    SampleIslandUtils::CenterStarts &starts,
+    const std::set<const VoronoiGraph::Node *> &done
+) {
+    // skip done starts
+    if (starts.empty())
+        return false; // no start
+    while (done.find(starts.back().neighbor->node) != done.end()) {
+        starts.pop_back();
+        if (starts.empty())
+            return false;
+    }
+    // fill new start
+    start = std::move(starts.back());
+    starts.pop_back();
+    return true;
+}
+
+bool add_support_on_neighbor_edge(
+    const VoronoiGraph::Node::Neighbor *neighbor,
+    coord_t& support_in,
+    SupportIslandPoints &results,
+    const SampleConfig &config
+) {
+    bool added = false;
+    coord_t edge_length = static_cast<coord_t>(neighbor->length());
+    while (edge_length >= support_in) {
+        double ratio = support_in / neighbor->length();
+        VoronoiGraph::Position position(neighbor, ratio);
+        results.push_back(std::make_unique<SupportCenterIslandPoint>(
+            position, &config, SupportIslandPoint::Type::center_line1
+        ));
+        support_in += config.max_distance;
+        added = true;
+    }
+    support_in -= edge_length;
+    return added;
+}
+
+/// <summary>
+/// Solve place where loop ends in already sampled area of island
+/// NOTE: still make a mistake in place of 2 ends
+/// (example could be logo of anarchy with already sampled circle and process inner 'Y')
+/// NOTE: do not count with supported distance in place of connect
+/// </summary>
+/// <param name="node_neighbor">Last neighbor to sample</param>
+/// <param name="support_in"></param>
+/// <param name="path"></param>
+/// <param name="results"></param>
+/// <param name="config"></param>
+void sample_connection_into_sampled_area(
+    const VoronoiGraph::Node::Neighbor &node_neighbor, 
+    coord_t support_in,
+    VoronoiGraph::Nodes path, // wanted copy
+    SupportIslandPoints &results,
+    const SampleConfig &config
+) {
+    add_support_on_neighbor_edge(&node_neighbor, support_in, results, config);
+    return; // TODO: sample small rest part WRT distance on connected place
+
+    if (support_in > config.max_distance / 2)
+        return; // no need to add new support
+
+    // add last support before connection into already supported area
+    path.push_back(node_neighbor.node);
+    std::reverse(path.begin(), path.end());
+    auto position_opt = SampleIslandUtils::create_position_on_path(path, 1 - support_in / 2);
+    if (position_opt.has_value()) {
+        results.push_back(std::make_unique<SupportCenterIslandPoint>(
+            *position_opt, &config, SupportIslandPoint::Type::center_line3
+        ));
+    }
+}
+} // namespace
+
 std::optional<VoronoiGraph::Position> SampleIslandUtils::sample_center(
     CenterStarts &                        new_starts,
     std::set<const VoronoiGraph::Node *> &done,
@@ -1038,73 +1193,61 @@ std::optional<VoronoiGraph::Position> SampleIslandUtils::sample_center(
     const Lines &                         lines,
     const SampleConfig &                  config)
 {
+    // Current place to sample
     CenterStart start(nullptr, {}, {});
-    bool use_new_start = true;
+    if (!pop_start(start, new_starts, done)) return {};
+
+    // sign that there was added point on start.path
+    // used to distiquish whether add support point on island edge
     bool is_continous = false;
 
-    while (use_new_start || start.neighbor->max_width() <= config.max_width_for_center_support_line) {
+    // Loop over thin part of island which need to be sampled on the voronoi skeleton.
-        // !! do not check max width for new start, it could be wide to tiny change
+    while (start.neighbor->max_width() <= config.max_width_for_center_support_line) {
-        if (use_new_start) { 
+        assert(done.find(start.neighbor->node) == done.end()); // not proccessed only        
-            use_new_start = false;
+        // add support when it is in distance from last added
-            // skip done starts
+        if (add_support_on_neighbor_edge(start.neighbor, start.support_in, results, config))
-            if (new_starts.empty()) return {}; // no start
-            while (done.find(new_starts.back().neighbor->node) != done.end()) {
-                new_starts.pop_back();
-                if (new_starts.empty()) return {};
-            }
-            // fill new start
-            start = std::move(new_starts.back());
-            new_starts.pop_back();
-            is_continous = false;
-        }
-
-        // add support on actual neighbor edge
-        coord_t edge_length = static_cast<coord_t>(start.neighbor->length());
-        while (edge_length >= start.support_in) {
-            double ratio = start.support_in / start.neighbor->length();
-            VoronoiGraph::Position position(start.neighbor, ratio);
-            results.push_back(std::make_unique<SupportCenterIslandPoint>(
-                position, &config, SupportIslandPoint::Type::center_line1));
-            start.support_in += config.max_distance;
             is_continous = true;
-        }
-        start.support_in -= edge_length;
 
         const VoronoiGraph::Node *node = start.neighbor->node;
         done.insert(node);
         // IMPROVE: A) limit length of path to config.minimal_support_distance
         // IMPROVE: B) store node in reverse order
         start.path.push_back(node);
+
+        // next neighbor is short cut to not push back and pop new_starts
         const VoronoiGraph::Node::Neighbor *next_neighbor = nullptr;
         for (const auto &node_neighbor : node->neighbors) {
-            if (done.find(node_neighbor.node) != done.end()) continue;
+            // Check wheather node is not previous one
+            if (start.path.size() > 1 && 
+                start.path[start.path.size() - 2] == node_neighbor.node) 
+                continue;
+            // Check other nodes wheather they are already done
+            if (done.find(node_neighbor.node) != done.end()) {
+                sample_connection_into_sampled_area(node_neighbor, start.support_in, start.path, results, config);
+                continue;
+            }
+            
             if (next_neighbor == nullptr) {
                 next_neighbor = &node_neighbor;
                 continue;
             }
-           new_starts.emplace_back(&node_neighbor, start.support_in, start.path); // search in side branch
+            new_starts.emplace_back(&node_neighbor, start.support_in, start.path); // search in side branch
         }
 
-        if (next_neighbor == nullptr) {
+        if (next_neighbor != nullptr) {
-            if (start.neighbor->min_width() != 0) {
-                std::reverse(start.path.begin(), start.path.end());
-                auto position_opt = create_position_on_path(start.path, start.support_in / 2);
-                if (position_opt.has_value()) {
-                    results.push_back(
-                        std::make_unique<SupportCenterIslandPoint>(
-                            *position_opt, &config,
-                            SupportIslandPoint::Type::center_line3));                    
-                }
-            } else {
-                // no neighbor to continue
-                create_sample_center_end(*start.neighbor, is_continous, start.path,
-                                         start.support_in, lines, results,
-                                         new_starts, config);
-            }
-            use_new_start = true;
-        } else {
             start.neighbor = next_neighbor;
+            continue;
         }
+        
+        // no neighbor to continue so sample edge of island
+        if(start.neighbor->min_width() == 0)
+            create_sample_center_end(*start.neighbor, is_continous, start.path,
+                                    start.support_in, lines, results,
+                                    new_starts, config);
+        // select next start
+        if (!pop_start(start, new_starts, done)) 
+            return {}; // finished
+        is_continous = false; // new branch for start was just selected
     }
 
     // create field start
@@ -1136,6 +1279,7 @@ void SampleIslandUtils::create_sample_center_end(
     const SampleConfig &                config)
 {
     // last neighbor?
+    assert(neighbor.min_width() == 0);
     if (neighbor.min_width() != 0) return;
 
     // sharp corner?
@@ -1389,18 +1533,25 @@ SampleIslandUtils::Field SampleIslandUtils::create_field(
     };
 
     size_t source_indexe_for_change = lines.size();
+
+    /// <summary>
+    /// Insert change into 
+    /// NOTE: separate functionality to be able force break from second loop
+    /// </summary>
+    /// <param name="lines">island(ExPolygon) converted to lines</param>
+    /// <param name="index"></param> ...
+    /// <returns>False when change lead to close loop(into first change) otherwise True</returns>
     auto insert_changes = [&wide_tiny_changes, &lines, &source_indexes, source_indexe_for_change]
     (size_t &index, Points &points, std::set<size_t> &done, size_t input_index)->bool {
-        bool is_first    = points.empty();
         auto change_item = wide_tiny_changes.find(index);
         while (change_item != wide_tiny_changes.end()) {
             const WideTinyChanges &changes = change_item->second;
             assert(!changes.empty());
             size_t change_index = 0;
-            if (!is_first) {
+            if (!points.empty()) { // Not first point, could lead to termination
-                const Point &           last_point = points.back();
+                const Point &last_point = points.back();
                 LineUtils::SortFromAToB pred(lines[index]);
-                bool                    no_change = false;
+                bool no_change = false;
                 while (pred.compare(changes[change_index].new_b, last_point)) {
                     ++change_index;
                     if (change_index >= changes.size()) {
@@ -1445,7 +1596,7 @@ SampleIslandUtils::Field SampleIslandUtils::create_field(
     outline_indexes.reserve(field_line_indexes.size());
     size_t input_index1 = tiny_wide_neighbor->edge->cell()->source_index();
     size_t input_index2 = tiny_wide_neighbor->edge->twin()->cell()->source_index();
-    size_t input_index  = std::min(input_index1, input_index2);
+    size_t input_index  = std::min(input_index1, input_index2); // Why select min index?
     size_t outline_index = input_index;
     std::set<size_t> done_indexes;
     do {
@@ -1778,13 +1929,10 @@ bool SampleIslandUtils::is_visualization_disabled()
 #ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_INITIAL_SAMPLE_POSITION_TO_SVG
     return false;
 #endif
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGNE_VD_TO_SVG
-    return false;
-#endif
 #ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_FIELD_TO_SVG
     return false;
 #endif
-#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG
+#ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGN_ONCE_TO_SVG_PATH
     return false;
 #endif
 #ifdef SLA_SAMPLE_ISLAND_UTILS_STORE_ALIGNED_TO_SVG

src/libslic3r/SLA/SupportIslands/SampleIslandUtils.hpp

@@ -24,6 +24,16 @@ class SampleIslandUtils
 public:
     SampleIslandUtils() = delete;
 
+    /// <summary>
+    /// Main entry for sample island
+    /// </summary>
+    /// <param name="island">Shape of island</param>
+    /// <param name="config">Configuration for sampler</param>
+    /// <returns>List of support points</returns>
+    static SupportIslandPoints uniform_cover_island(
+        const ExPolygon &island, const SampleConfig &config
+    );
+
     /// <summary>
     /// Uniform sample expolygon area by points inside Equilateral triangle center
     /// </summary>

src/libslic3r/SLA/SupportPointGenerator.cpp

@@ -9,6 +9,10 @@
 #include "libslic3r/Execution/Execution.hpp"
 #include "libslic3r/KDTreeIndirect.hpp"
 
+// SupportIslands
+#include "libslic3r/SLA/SupportIslands/SampleConfigFactory.hpp"
+#include "libslic3r/SLA/SupportIslands/SampleIslandUtils.hpp"
+
 using namespace Slic3r;
 using namespace Slic3r::sla;
 
@@ -183,14 +187,14 @@ Point intersection(const Point &p1, const Point &p2, const Point &cnt, double r2
 /// <param name="part">Current layer part to process</param>
 /// <param name="prev_grids">Grids which will be moved to current grid</param>
 /// <returns>Grid for given part</returns>
-NearPoints create_part_grid(
+NearPoints create_near_points(
     const LayerParts &prev_layer_parts,
     const LayerPart &part,
     std::vector<NearPoints> &prev_grids
 ) {
     const LayerParts::const_iterator &prev_part_it = part.prev_parts.front().part_it;
     size_t index_of_prev_part = prev_part_it - prev_layer_parts.begin();
-    NearPoints part_grid = (prev_part_it->next_parts.size() == 1)?
+    NearPoints near_points = (prev_part_it->next_parts.size() == 1)?
         std::move(prev_grids[index_of_prev_part]) :
         // Need a copy there are multiple parts above previus one
         prev_grids[index_of_prev_part]; // copy    
@@ -200,27 +204,27 @@ NearPoints create_part_grid(
         const LayerParts::const_iterator &prev_part_it = part.prev_parts[i].part_it;
         size_t index_of_prev_part = prev_part_it - prev_layer_parts.begin();
         if (prev_part_it->next_parts.size() == 1) {
-            part_grid.merge(std::move(prev_grids[index_of_prev_part]));
+            near_points.merge(std::move(prev_grids[index_of_prev_part]));
         } else { // Need a copy there are multiple parts above previus one
             NearPoints grid_ = prev_grids[index_of_prev_part]; // copy
-            part_grid.merge(std::move(grid_));
+            near_points.merge(std::move(grid_));
         }
     }
-    return part_grid;
+    return near_points;
 }
 
 /// <summary>
-/// Add support point to part_grid when it is neccessary
+/// Add support point to near_points when it is neccessary
 /// </summary>
 /// <param name="part">Current part - keep samples</param>
 /// <param name="config">Configuration to sample</param>
-/// <param name="part_grid">Keep previous sampled suppport points</param>
+/// <param name="near_points">Keep previous sampled suppport points</param>
 /// <param name="part_z">current z coordinate of part</param>
 /// <param name="maximal_radius">Max distance to seach support for sample</param>
 void support_part_overhangs(
     const LayerPart &part,
     const SupportPointGeneratorConfig &config,
-    NearPoints &part_grid,
+    NearPoints &near_points,
     float part_z,
     coord_t maximal_radius
 ) {
@@ -239,9 +243,9 @@ void support_part_overhangs(
     };
 
     for (const Point &p : part.samples) {
-        if (!part_grid.exist_true_in_radius(p, maximal_radius, is_supported)) {
+        if (!near_points.exist_true_in_radius(p, maximal_radius, is_supported)) {
             // not supported sample, soo create new support point
-            part_grid.add(LayerSupportPoint{
+            near_points.add(LayerSupportPoint{
                 SupportPoint{
                     Vec3f{unscale<float>(p.x()), unscale<float>(p.y()), part_z},
                     /* head_front_radius */ 0.4f,
@@ -256,30 +260,31 @@ void support_part_overhangs(
     }
 }
 
-Points uniformly_sample(const ExPolygon &island, const SupportPointGeneratorConfig &cfg) {
-    // TODO: Implement it
-    return Points{island.contour.centroid()};
-}
-
 /// <summary>
 /// Sample part as Island
 /// Result store to grid
 /// </summary>
 /// <param name="part">Island to support</param>
-/// <param name="part_grid">OUT place to store new supports</param>
+/// <param name="near_points">OUT place to store new supports</param>
 /// <param name="part_z">z coordinate of part</param>
 /// <param name="cfg"></param>
-void support_island(const LayerPart &part, NearPoints& part_grid, float part_z,
+void support_island(const LayerPart &part, NearPoints& near_points, float part_z,
-    const SupportPointGeneratorConfig &cfg) {
+    const SupportPointGeneratorConfig &cfg) { 
-    Points pts = uniformly_sample(*part.shape, cfg);
+    SampleConfig sample_cfg = SampleConfigFactory::create(cfg);
-    for (const Point &pt : pts)
+    SupportIslandPoints samples = SampleIslandUtils::uniform_cover_island(*part.shape, sample_cfg);
-        part_grid.add(LayerSupportPoint{
+    //samples = {std::make_unique<SupportIslandPoint>(island.contour.centroid())};
+    for (const SupportIslandPointPtr &sample : samples)
+        near_points.add(LayerSupportPoint{
             SupportPoint{
-                Vec3f{unscale<float>(pt.x()), unscale<float>(pt.y()), part_z},
+                Vec3f{
+                    unscale<float>(sample->point.x()), 
+                    unscale<float>(sample->point.y()), 
+                    part_z
+                },
                 /* head_front_radius */ 0.4f,
                 SupportPointType::island
             },
-            /* position_on_layer */ pt,
+            /* position_on_layer */ sample->point,
             /* direction_to_mass */ Point(0,0), // direction from bottom
             /* radius_curve_index */ 0,
             /* current_radius */ static_cast<coord_t>(scale_(cfg.support_curve.front().x()))
@@ -471,15 +476,15 @@ void prepare_supports_for_layer(LayerSupportPoints &supports, float layer_z,
 /// Due to be able support in same area again(overhang above another overhang)
 /// Wanted Side effect, it supports thiny part of overhangs
 /// </summary>
-/// <param name="part_grid"></param>
+/// <param name="near_points"></param>
 /// <param name="part"></param>
-void remove_supports_out_of_part(NearPoints& part_grid, const LayerPart &part) { 
+void remove_supports_out_of_part(NearPoints& near_points, const LayerPart &part) { 
     
     // Must be greater than surface texture and lower than self supporting area
     // May be use maximal island distance
     float delta = scale_(5.);
     ExPolygons extend_shape = offset_ex(*part.shape, delta, ClipperLib::jtSquare);
-    part_grid.remove_out_of(extend_shape);
+    near_points.remove_out_of(extend_shape);
 }
 
 } // namespace
@@ -651,10 +656,10 @@ LayerSupportPoints Slic3r::sla::generate_support_points(
                 // first layer should have empty prev_part
                 assert(layer_id != 0);
                 const LayerParts &prev_layer_parts = layers[layer_id - 1].parts;
-                NearPoints part_grid = create_part_grid(prev_layer_parts, part, prev_grids);
+                NearPoints near_points = create_near_points(prev_layer_parts, part, prev_grids);
-                remove_supports_out_of_part(part_grid, part);
+                remove_supports_out_of_part(near_points, part);
-                support_part_overhangs(part, config, part_grid, layer.print_z, maximal_radius);
+                support_part_overhangs(part, config, near_points, layer.print_z, maximal_radius);
-                grids.push_back(std::move(part_grid));
+                grids.push_back(std::move(near_points));
             }
         }
         prev_grids = std::move(grids);