Slic3r::sla::ConcaveHull Class Reference

A fake concave hull that is constructed by connecting separate shapes with explicit bridges. Bridges are generated from each shape's centroid to the center of the "scene" which is the centroid calculated from the shape centroids (a star is created...) More...

#include <src/libslic3r/SLA/ConcaveHull.hpp>

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Public Member Functions
	ConcaveHull (const ExPolygons &polys, double merge_dist, ThrowOnCancel thr)
	ConcaveHull (const Polygons &polys, double mergedist, ThrowOnCancel thr)
const Polygons &	polygons () const
ExPolygons	to_expolygons () const

Private Member Functions
Points	calculate_centroids () const
void	merge_polygons ()
void	add_connector_rectangles (const Points &centroids, coord_t max_dist, ThrowOnCancel thr)

Static Private Member Functions
static Point	centroid (const Points &pp)
static Point	centroid (const Polygon &poly)

Private Attributes
Polygons	m_polys

Detailed Description

A fake concave hull that is constructed by connecting separate shapes with explicit bridges. Bridges are generated from each shape's centroid to the center of the "scene" which is the centroid calculated from the shape centroids (a star is created...)

Constructor & Destructor Documentation

ConcaveHull() [1/2]

Slic3r::sla::ConcaveHull::ConcaveHull ( const ExPolygons &  polys, double  merge_dist, ThrowOnCancel  thr  )

inline

        : ConcaveHull{to_polygons(polys), merge_dist, thr} {}

ConcaveHull() [2/2]

Slic3r::sla::ConcaveHull::ConcaveHull	(	const Polygons &	polys,
		double	mergedist,
		ThrowOnCancel	thr
	)

{
    if(polys.empty()) return;
 
    m_polys = polys;
    merge_polygons();
 
    if(m_polys.size() == 1) return;
 
    Points centroids = calculate_centroids();
 
    add_connector_rectangles(centroids, scaled(mergedist), thr);
 
    merge_polygons();
}

References add_connector_rectangles(), calculate_centroids(), m_polys, merge_polygons(), and Slic3r::scaled().

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Member Function Documentation

add_connector_rectangles()

void Slic3r::sla::ConcaveHull::add_connector_rectangles ( const Points &  centroids, coord_t  max_dist, ThrowOnCancel  thr  )

private

{
    // Centroid of the centroids of islands. This is where the additional
    // connector sticks are routed.
    Point cc = centroid(centroids);
 
    PointIndex ctrindex;
    unsigned  idx = 0;
    for(const Point &ct : centroids) ctrindex.insert(to_vec3(ct), idx++);
 
    m_polys.reserve(m_polys.size() + centroids.size());
 
    idx = 0;
    for (const Point &c : centroids) {
        thr();
 
        double dx = c.x() - cc.x(), dy = c.y() - cc.y();
        double l  = std::sqrt(dx * dx + dy * dy);
        double nx = dx / l, ny = dy / l;
 
        const Point &ct = centroids[idx];
 
        std::vector<PointIndexEl> result = ctrindex.nearest(to_vec3(ct), 2);
 
        double dist = max_dist;
        for (const PointIndexEl &el : result)
            if (el.second != idx) {
                dist = Line(to_vec2(el.first), ct).length();
                break;
            }
 
        idx++;
 
        if (dist >= max_dist) return;
 
        Polygon r;
        r.points.reserve(3);
        r.points.emplace_back(cc);
 
        Point n(scaled(nx), scaled(ny));
        r.points.emplace_back(c + Point(n.y(), -n.x()));
        r.points.emplace_back(c + Point(-n.y(), n.x()));
        offset(r, scaled<float>(1.));
 
        m_polys.emplace_back(r);
    }
}

References centroid(), Slic3r::sla::PointIndex::insert(), Slic3r::Line::length(), m_polys, Slic3r::sla::PointIndex::nearest(), Slic3r::offset(), Slic3r::MultiPoint::points, Slic3r::scaled(), Slic3r::sla::to_vec2(), and Slic3r::sla::to_vec3().

Referenced by ConcaveHull().

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calculate_centroids()

Points Slic3r::sla::ConcaveHull::calculate_centroids ( ) const

private

{
    // We get the centroids of all the islands in the 2D slice
    Points centroids;
    centroids.reserve(m_polys.size());
    std::transform(m_polys.begin(), m_polys.end(),
                   std::back_inserter(centroids),
                   [](const Polygon &poly) { return centroid(poly); });
 
    return centroids;
}

References m_polys.

Referenced by ConcaveHull().

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centroid() [1/2]

Point Slic3r::sla::ConcaveHull::centroid ( const Points &  pp )

staticprivate

{
    Point c;
    switch(pp.size()) {
    case 0: break;
    case 1: c = pp.front(); break;
    case 2: c = (pp[0] + pp[1]) / 2; break;
    default: {
        auto MAX = std::numeric_limits<Point::coord_type>::max();
        auto MIN = std::numeric_limits<Point::coord_type>::min();
        Point min = {MAX, MAX}, max = {MIN, MIN};
 
        for(auto& p : pp) {
            if(p(0) < min(0)) min(0) = p(0);
            if(p(1) < min(1)) min(1) = p(1);
            if(p(0) > max(0)) max(0) = p(0);
            if(p(1) > max(1)) max(1) = p(1);
        }
        c(0) = min(0) + (max(0) - min(0)) / 2;
        c(1) = min(1) + (max(1) - min(1)) / 2;
        break;
    }
    }
 
    return c;
}

References MAX, and MIN.

Referenced by add_connector_rectangles().

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centroid() [2/2]

static Point Slic3r::sla::ConcaveHull::centroid ( const Polygon &  poly )

inlinestaticprivate

{ return poly.centroid(); }

References Slic3r::Polygon::centroid().

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merge_polygons()

void Slic3r::sla::ConcaveHull::merge_polygons ( )

private

{ m_polys = get_contours(union_ex(m_polys)); }

References Slic3r::sla::get_contours(), m_polys, and Slic3r::union_ex().

Referenced by ConcaveHull().

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polygons()

const Polygons & Slic3r::sla::ConcaveHull::polygons ( ) const

inline

{ return m_polys; }

References m_polys.

Referenced by Slic3r::sla::offset_waffle_style().

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to_expolygons()

ExPolygons Slic3r::sla::ConcaveHull::to_expolygons

(

)

const

{
    auto ret = reserve_vector<ExPolygon>(m_polys.size());
    for (const Polygon &p : m_polys) ret.emplace_back(ExPolygon(p));
    return ret;
}

References m_polys.

Member Data Documentation

m_polys

Polygons Slic3r::sla::ConcaveHull::m_polys

private

Referenced by ConcaveHull(), add_connector_rectangles(), calculate_centroids(), merge_polygons(), polygons(), and to_expolygons().

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The documentation for this class was generated from the following files:

• src/libslic3r/SLA/ConcaveHull.hpp
• src/libslic3r/SLA/ConcaveHull.cpp