ENH: new seam strategy from prusa2.5

As title. Thanks @Prusa

Signed-off-by: salt.wei <salt.wei@bambulab.com>
Change-Id: I2fa177e27ac53211952ea9b6c62e98182b8f05ce

src/libslic3r/AABBTreeLines.hpp

@@ -0,0 +1,112 @@
+#ifndef SRC_LIBSLIC3R_AABBTREELINES_HPP_
+#define SRC_LIBSLIC3R_AABBTREELINES_HPP_
+
+#include "libslic3r/Point.hpp"
+#include "libslic3r/EdgeGrid.hpp"
+#include "libslic3r/AABBTreeIndirect.hpp"
+#include "libslic3r/Line.hpp"
+
+namespace Slic3r {
+
+namespace AABBTreeLines {
+
+namespace detail {
+
+template<typename ALineType, typename ATreeType, typename AVectorType>
+struct IndexedLinesDistancer {
+    using LineType = ALineType;
+    using TreeType = ATreeType;
+    using VectorType = AVectorType;
+    using ScalarType = typename VectorType::Scalar;
+
+    const std::vector<LineType> &lines;
+    const TreeType &tree;
+
+    const VectorType origin;
+
+    inline VectorType closest_point_to_origin(size_t primitive_index,
+            ScalarType &squared_distance) {
+        VectorType nearest_point;
+        const LineType &line = lines[primitive_index];
+        squared_distance = line_alg::distance_to_squared(line, origin, &nearest_point);
+        return nearest_point;
+    }
+};
+
+}
+
+// Build a balanced AABB Tree over a vector of float lines, balancing the tree
+// on centroids of the lines.
+// Epsilon is applied to the bounding boxes of the AABB Tree to cope with numeric inaccuracies
+// during tree traversal.
+template<typename LineType>
+inline AABBTreeIndirect::Tree<2, typename LineType::Scalar> build_aabb_tree_over_indexed_lines(
+        const std::vector<LineType> &lines,
+        //FIXME do we want to apply an epsilon?
+        const float eps = 0)
+        {
+    using TreeType = AABBTreeIndirect::Tree<2, typename LineType::Scalar>;
+//    using              CoordType      = typename TreeType::CoordType;
+    using VectorType = typename TreeType::VectorType;
+    using BoundingBox = typename TreeType::BoundingBox;
+
+    struct InputType {
+        size_t idx() const {
+            return m_idx;
+        }
+        const BoundingBox& bbox() const {
+            return m_bbox;
+        }
+        const VectorType& centroid() const {
+            return m_centroid;
+        }
+
+        size_t m_idx;
+        BoundingBox m_bbox;
+        VectorType m_centroid;
+    };
+
+    std::vector<InputType> input;
+    input.reserve(lines.size());
+    const VectorType veps(eps, eps);
+    for (size_t i = 0; i < lines.size(); ++i) {
+        const LineType &line = lines[i];
+        InputType n;
+        n.m_idx = i;
+        n.m_centroid = (line.a + line.b) * 0.5;
+        n.m_bbox = BoundingBox(line.a, line.a);
+        n.m_bbox.extend(line.b);
+        n.m_bbox.min() -= veps;
+        n.m_bbox.max() += veps;
+        input.emplace_back(n);
+    }
+
+    TreeType out;
+    out.build(std::move(input));
+    return out;
+}
+
+// Finding a closest line, its closest point and squared distance to the closest point
+// Returns squared distance to the closest point or -1 if the input is empty.
+template<typename LineType, typename TreeType, typename VectorType>
+inline typename VectorType::Scalar squared_distance_to_indexed_lines(
+        const std::vector<LineType> &lines,
+        const TreeType &tree,
+        const VectorType &point,
+        size_t &hit_idx_out,
+        Eigen::PlainObjectBase<VectorType> &hit_point_out)
+        {
+    using Scalar = typename VectorType::Scalar;
+    auto distancer = detail::IndexedLinesDistancer<LineType, TreeType, VectorType>
+            { lines, tree, point };
+    return tree.empty() ?
+                          Scalar(-1) :
+                          AABBTreeIndirect::detail::squared_distance_to_indexed_primitives_recursive(distancer, size_t(0), Scalar(0),
+                                  std::numeric_limits<Scalar>::infinity(), hit_idx_out, hit_point_out);
+}
+
+}
+
+}
+
+#endif /* SRC_LIBSLIC3R_AABBTREELINES_HPP_ */