only_one_perimeter_top for arachne (& not over bridges from orca)

from pr by vovodroid from orca from SuSi
#4022

src/libslic3r/ClipperUtils.cpp

@@ -59,8 +59,124 @@ bool export_clipper_input_polygons_bin(const char *path, const ClipperLib::Paths
 namespace ClipperUtils {
     Points EmptyPathsProvider::s_empty_points;
     Points SinglePathProvider::s_end;
+
+
+    // Clip source polygon to be used as a clipping polygon with a bouding box around the source (to be clipped)
+    // polygon. Useful as an optimization for expensive ClipperLib operations, for example when clipping source
+    // polygons one by one with a set of polygons covering the whole layer below.
+    template<typename PointsType>
+    inline void clip_clipper_polygon_with_subject_bbox_templ(const PointsType & src,
+                                                             const BoundingBox &bbox,
+                                                             PointsType &       out)
+    {
+        using PointType = typename PointsType::value_type;
+        out.clear();
+        const size_t cnt = src.size();
+        if (cnt < 3)
+            return;
+        enum class Side { Left = 1, Right = 2, Top = 4, Bottom = 8 };
+        auto sides = [bbox](const PointType &p) {
+            return int(p.x() < bbox.min.x()) * int(Side::Left) + int(p.x() > bbox.max.x()) * int(Side::Right) +
+                   int(p.y() < bbox.min.y()) * int(Side::Bottom) + int(p.y() > bbox.max.y()) * int(Side::Top);
+        };
+        int          sides_prev = sides(src.back());
+        int          sides_this = sides(src.front());
+        const size_t last       = cnt - 1;
+        for (size_t i = 0; i < last; ++i) {
+            int sides_next = sides(src[i + 1]);
+            if ( // This point is inside. Take it.
+                sides_this == 0 ||
+                // Either this point is outside and previous or next is inside, or
+                // the edge possibly cuts corner of the bounding box.
+                (sides_prev & sides_this & sides_next) == 0) {
+                out.emplace_back(src[i]);
+                sides_prev = sides_this;
+            } else {
+                // All the three points (this, prev, next) are outside at the same side.
+                // Ignore this point.
+            }
+            sides_this = sides_next;
+        }
+        // Never produce just a single point output polygon.
+        if (!out.empty())
+            if (int sides_next = sides(out.front());
+                // The last point is inside. Take it.
+                sides_this == 0 ||
+                // Either this point is outside and previous or next is inside, or
+                // the edge possibly cuts corner of the bounding box.
+                (sides_prev & sides_this & sides_next) == 0)
+                out.emplace_back(src.back());
+    }
+    void clip_clipper_polygon_with_subject_bbox(const Points &src, const BoundingBox &bbox, Points &out)
+    {
+        clip_clipper_polygon_with_subject_bbox_templ(src, bbox, out);
+    }
+    void clip_clipper_polygon_with_subject_bbox(const ZPoints &src, const BoundingBox &bbox, ZPoints &out)
+    {
+        clip_clipper_polygon_with_subject_bbox_templ(src, bbox, out);
+    }
+    template<typename PointsType>
+    [[nodiscard]] PointsType clip_clipper_polygon_with_subject_bbox_templ(const PointsType & src,
+                                                                          const BoundingBox &bbox)
+    {
+        PointsType out;
+        clip_clipper_polygon_with_subject_bbox(src, bbox, out);
+        return out;
+    }
+    [[nodiscard]] Points clip_clipper_polygon_with_subject_bbox(const Points &src, const BoundingBox &bbox)
+    {
+        return clip_clipper_polygon_with_subject_bbox_templ(src, bbox);
+    }
+    [[nodiscard]] ZPoints clip_clipper_polygon_with_subject_bbox(const ZPoints &src, const BoundingBox &bbox)
+    {
+        return clip_clipper_polygon_with_subject_bbox_templ(src, bbox);
+    }
+    void clip_clipper_polygon_with_subject_bbox(const Polygon &src, const BoundingBox &bbox, Polygon &out)
+    {
+        clip_clipper_polygon_with_subject_bbox(src.points, bbox, out.points);
+    }
+    [[nodiscard]] Polygon clip_clipper_polygon_with_subject_bbox(const Polygon &src, const BoundingBox &bbox)
+    {
+        Polygon out;
+        clip_clipper_polygon_with_subject_bbox(src.points, bbox, out.points);
+        return out;
+    }
+    [[nodiscard]] Polygons clip_clipper_polygons_with_subject_bbox(const Polygons &src, const BoundingBox &bbox)
+    {
+        Polygons out;
+        out.reserve(src.size());
+        for (const Polygon &p : src) out.emplace_back(clip_clipper_polygon_with_subject_bbox(p, bbox));
+        out.erase(std::remove_if(out.begin(), out.end(), [](const Polygon &polygon) { return polygon.empty(); }),
+                  out.end());
+        return out;
+    }
+    [[nodiscard]] Polygons clip_clipper_polygons_with_subject_bbox(const ExPolygon &src, const BoundingBox &bbox)
+    {
+        Polygons out;
+        out.reserve(src.num_contours());
+        out.emplace_back(clip_clipper_polygon_with_subject_bbox(src.contour, bbox));
+        for (const Polygon &p : src.holes) out.emplace_back(clip_clipper_polygon_with_subject_bbox(p, bbox));
+        out.erase(std::remove_if(out.begin(), out.end(), [](const Polygon &polygon) { return polygon.empty(); }),
+                  out.end());
+        return out;
+    }
+    [[nodiscard]] Polygons clip_clipper_polygons_with_subject_bbox(const ExPolygons &src, const BoundingBox &bbox)
+    {
+        Polygons out;
+        out.reserve(number_polygons(src));
+        for (const ExPolygon &p : src) {
+            Polygons temp = clip_clipper_polygons_with_subject_bbox(p, bbox);
+            out.insert(out.end(), temp.begin(), temp.end());
+        }
+
+        out.erase(std::remove_if(out.begin(), out.end(), [](const Polygon &polygon) { return polygon.empty(); }),
+                  out.end());
+        return out;
+    }
 }
 
+
+
 static ExPolygons PolyTreeToExPolygons(ClipperLib::PolyTree &&polytree)
 {
     struct Inner {

src/libslic3r/ClipperUtils.hpp

@@ -297,7 +297,23 @@ namespace ClipperUtils {
         const SurfacesPtr &m_surfaces;
         size_t             m_size;
     };
-}
+
+    using ZPoint = Vec3i32;
+    using ZPoints = std::vector<Vec3i32>;
+
+    // Clip source polygon to be used as a clipping polygon with a bouding box around the source (to be clipped) polygon.
+    // Useful as an optimization for expensive ClipperLib operations, for example when clipping source polygons one by
+    // one with a set of polygons covering the whole layer below.
+    void clip_clipper_polygon_with_subject_bbox(const Points &src, const BoundingBox &bbox, Points &out);
+    void clip_clipper_polygon_with_subject_bbox(const ZPoints &src, const BoundingBox &bbox, ZPoints &out);
+    [[nodiscard]] Points  clip_clipper_polygon_with_subject_bbox(const Points &src, const BoundingBox &bbox);
+    [[nodiscard]] ZPoints clip_clipper_polygon_with_subject_bbox(const ZPoints &src, const BoundingBox &bbox);
+    void clip_clipper_polygon_with_subject_bbox(const Polygon &src, const BoundingBox &bbox, Polygon &out);
+    [[nodiscard]] Polygon  clip_clipper_polygon_with_subject_bbox(const Polygon &src, const BoundingBox &bbox);
+    [[nodiscard]] Polygons clip_clipper_polygons_with_subject_bbox(const Polygons &src, const BoundingBox &bbox);
+    [[nodiscard]] Polygons clip_clipper_polygons_with_subject_bbox(const ExPolygon &src, const BoundingBox &bbox);
+    [[nodiscard]] Polygons clip_clipper_polygons_with_subject_bbox(const ExPolygons &src, const BoundingBox &bbox);
+    }
 
 // Perform union of input polygons using the non-zero rule, convert to ExPolygons.
 ExPolygons ClipperPaths_to_Slic3rExPolygons(const ClipperLib::Paths &input, bool do_union = false);