C++ Clipper::Clear方法代码示例

void _clipper_do(const ClipperLib::ClipType clipType, const Slic3r::Polygons &subject, 
    const Slic3r::Polygons &clip, T &retval, const ClipperLib::PolyFillType fillType, const bool safety_offset_)
{
    // read input
    ClipperLib::Paths* input_subject = new ClipperLib::Paths();
    ClipperLib::Paths* input_clip    = new ClipperLib::Paths();
    Slic3rMultiPoints_to_ClipperPaths(subject, *input_subject);
    Slic3rMultiPoints_to_ClipperPaths(clip,    *input_clip);
    
    // perform safety offset
    if (safety_offset_) {
        if (clipType == ClipperLib::ctUnion) {
            safety_offset(input_subject);
        } else {
            safety_offset(input_clip);
        }
    }
    
    // init Clipper
    ClipperLib::Clipper clipper;
    clipper.Clear();
    
    // add polygons
    clipper.AddPaths(*input_subject, ClipperLib::ptSubject, true);
    delete input_subject;
    clipper.AddPaths(*input_clip, ClipperLib::ptClip, true);
    delete input_clip;
    
    // perform operation
    clipper.Execute(clipType, retval, fillType, fillType);
}

// Fix of #117: A large fractal pyramid takes ages to slice
// The Clipper library has difficulties processing overlapping polygons.
// Namely, the function Clipper::JoinCommonEdges() has potentially a terrible time complexity if the output
// of the operation is of the PolyTree type.
// This function implmenets a following workaround:
// 1) Peform the Clipper operation with the output to Paths. This method handles overlaps in a reasonable time.
// 2) Run Clipper Union once again to extract the PolyTree from the result of 1).
inline ClipperLib::PolyTree _clipper_do_polytree2(const ClipperLib::ClipType clipType, const Polygons &subject, 
    const Polygons &clip, const ClipperLib::PolyFillType fillType, const bool safety_offset_)
{
    // read input
    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
    ClipperLib::Paths input_clip    = Slic3rMultiPoints_to_ClipperPaths(clip);
    
    // perform safety offset
    if (safety_offset_)
        safety_offset((clipType == ClipperLib::ctUnion) ? &input_subject : &input_clip);
    
    ClipperLib::Clipper clipper;
    clipper.AddPaths(input_subject, ClipperLib::ptSubject, true);
    clipper.AddPaths(input_clip,    ClipperLib::ptClip,    true);
    // Perform the operation with the output to input_subject.
    // This pass does not generate a PolyTree, which is a very expensive operation with the current Clipper library
    // if there are overapping edges.
    clipper.Execute(clipType, input_subject, fillType, fillType);
    // Perform an additional Union operation to generate the PolyTree ordering.
    clipper.Clear();
    clipper.AddPaths(input_subject, ClipperLib::ptSubject, true);
    ClipperLib::PolyTree retval;
    clipper.Execute(ClipperLib::ctUnion, retval, fillType, fillType);
    return retval;
}

void _clipper_do(const ClipperLib::ClipType clipType, const Slic3r::Polylines &subject, 
    const Slic3r::Polygons &clip, ClipperLib::PolyTree* retval, const ClipperLib::PolyFillType fillType,
    const bool safety_offset_)
{
    PROFILE_BLOCK(_clipper_do_polylines);

    // read input
    ClipperLib::Paths input_subject, input_clip;
    Slic3rMultiPoints_to_ClipperPaths(subject, &input_subject);
    Slic3rMultiPoints_to_ClipperPaths(clip,    &input_clip);
    
    // perform safety offset
    if (safety_offset_) safety_offset(&input_clip);
    
    // init Clipper
    ClipperLib::Clipper clipper;
    clipper.Clear();
    
    // add polygons
    {
        PROFILE_BLOCK(_clipper_do_polylines_AddPaths);
        clipper.AddPaths(input_subject, ClipperLib::ptSubject, false);
        clipper.AddPaths(input_clip,    ClipperLib::ptClip,    true);
    }
    
    // perform operation
    {
        PROFILE_BLOCK(_clipper_do_polylines_Execute);
        clipper.Execute(clipType, *retval, fillType, fillType);
    }
}

ClipperLib::PolyTree
_clipper_do(const ClipperLib::ClipType clipType, const Polylines &subject, 
    const Polygons &clip, const ClipperLib::PolyFillType fillType,
    const bool safety_offset_)
{
    // read input
    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
    ClipperLib::Paths input_clip    = Slic3rMultiPoints_to_ClipperPaths(clip);
    
    // perform safety offset
    if (safety_offset_) safety_offset(&input_clip);
    
    // init Clipper
    ClipperLib::Clipper clipper;
    clipper.Clear();
    
    // add polygons
    clipper.AddPaths(input_subject, ClipperLib::ptSubject, false);
    clipper.AddPaths(input_clip,    ClipperLib::ptClip,    true);
    
    // perform operation
    ClipperLib::PolyTree retval;
    clipper.Execute(clipType, retval, fillType, fillType);
    return retval;
}

// This is a safe variant of the polygon offset, tailored for a single ExPolygon:
// a single polygon with multiple non-overlapping holes.
// Each contour and hole is offsetted separately, then the holes are subtracted from the outer contours.
ClipperLib::Paths _offset(const Slic3r::ExPolygon &expolygon, const float delta,
    ClipperLib::JoinType joinType, double miterLimit)
{
//    printf("new ExPolygon offset\n");
    // 1) Offset the outer contour.
    const float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
    ClipperLib::Paths contours;
    {
        ClipperLib::Path input = Slic3rMultiPoint_to_ClipperPath(expolygon.contour);
        scaleClipperPolygon(input);
        ClipperLib::ClipperOffset co;
        if (joinType == jtRound)
            co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
        else
            co.MiterLimit = miterLimit;
        co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
        co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
        co.Execute(contours, delta_scaled);
    }

    // 2) Offset the holes one by one, collect the results.
    ClipperLib::Paths holes;
    {
        holes.reserve(expolygon.holes.size());
        for (Polygons::const_iterator it_hole = expolygon.holes.begin(); it_hole != expolygon.holes.end(); ++ it_hole) {
            ClipperLib::Path input = Slic3rMultiPoint_to_ClipperPath_reversed(*it_hole);
            scaleClipperPolygon(input);
            ClipperLib::ClipperOffset co;
            if (joinType == jtRound)
                co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
            else
                co.MiterLimit = miterLimit;
            co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
            co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
            ClipperLib::Paths out;
            co.Execute(out, - delta_scaled);
            holes.insert(holes.end(), out.begin(), out.end());
        }
    }

    // 3) Subtract holes from the contours.
    ClipperLib::Paths output;
    if (holes.empty()) {
        output = std::move(contours);
    } else {
        ClipperLib::Clipper clipper;
        clipper.Clear();
        clipper.AddPaths(contours, ClipperLib::ptSubject, true);
        clipper.AddPaths(holes, ClipperLib::ptClip, true);
        clipper.Execute(ClipperLib::ctDifference, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
    }
    
    // 4) Unscale the output.
    unscaleClipperPolygons(output);
    return output;
}

ExPolygons
ClipperPaths_to_Slic3rExPolygons(const ClipperLib::Paths &input)
{
    // init Clipper
    ClipperLib::Clipper clipper;
    clipper.Clear();
    
    // perform union
    clipper.AddPaths(input, ClipperLib::ptSubject, true);
    ClipperLib::PolyTree polytree;
    clipper.Execute(ClipperLib::ctUnion, polytree, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);  // offset results work with both EvenOdd and NonZero
    
    // write to ExPolygons object
    return PolyTreeToExPolygons(polytree);
}

Polygons top_level_islands(const Slic3r::Polygons &polygons)
{
    // init Clipper
    ClipperLib::Clipper clipper;
    clipper.Clear();
    // perform union
    clipper.AddPaths(Slic3rMultiPoints_to_ClipperPaths(polygons), ClipperLib::ptSubject, true);
    ClipperLib::PolyTree polytree;
    clipper.Execute(ClipperLib::ctUnion, polytree, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd); 
    // Convert only the top level islands to the output.
    Polygons out;
    out.reserve(polytree.ChildCount());
    for (int i = 0; i < polytree.ChildCount(); ++i)
        out.emplace_back(ClipperPath_to_Slic3rPolygon(polytree.Childs[i]->Contour));
    return out;
}

void
ClipperPaths_to_Slic3rExPolygons(const ClipperLib::Paths &input, Slic3r::ExPolygons &output)
{
    // init Clipper
    ClipperLib::Clipper clipper;
    clipper.Clear();
    
    // perform union
    clipper.AddPaths(input, ClipperLib::ptSubject, true);
    ClipperLib::PolyTree* polytree = new ClipperLib::PolyTree();
    clipper.Execute(ClipperLib::ctUnion, *polytree, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);  // offset results work with both EvenOdd and NonZero
    
    // write to ExPolygons object
    output.clear();
    PolyTreeToExPolygons(*polytree, output);
    
    delete polytree;
}

GeometryCollection fixupPolygons(const GeometryCollection& rings) {
    ClipperLib::Clipper clipper;
    clipper.StrictlySimple(true);

    for (const auto& ring : rings) {
        clipper.AddPath(toClipperPath(ring), ClipperLib::ptSubject, true);
    }

    ClipperLib::PolyTree polygons;
    clipper.Execute(ClipperLib::ctUnion, polygons, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);
    clipper.Clear();

    GeometryCollection result;
    for (auto * polynode : polygons.Childs) {
        processPolynodeBranch(polynode, result);
    }
    return result;
}

// This is a safe variant of the polygon offset, tailored for a single ExPolygon:
// a single polygon with multiple non-overlapping holes.
// Each contour and hole is offsetted separately, then the holes are subtracted from the outer contours.
void offset(const Slic3r::ExPolygons &expolygons, ClipperLib::Paths* retval, const float delta,
    ClipperLib::JoinType joinType, double miterLimit)
{
//    printf("new ExPolygon offset\n");
    const float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
    ClipperLib::Paths contours;
    ClipperLib::Paths holes;
    contours.reserve(expolygons.size());
    {
        size_t n_holes = 0;
        for (size_t i = 0; i < expolygons.size(); ++ i)
            n_holes += expolygons[i].holes.size();
        holes.reserve(n_holes);
    }

    for (Slic3r::ExPolygons::const_iterator it_expoly = expolygons.begin(); it_expoly != expolygons.end(); ++ it_expoly) {
        // 1) Offset the outer contour.
        {
            ClipperLib::Path input;
            Slic3rMultiPoint_to_ClipperPath(it_expoly->contour, &input);
            scaleClipperPolygon(input);
            ClipperLib::ClipperOffset co;
            if (joinType == jtRound)
                co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
            else
                co.MiterLimit = miterLimit;
            co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
            ClipperLib::Paths out;
            co.Execute(out, delta_scaled);
            contours.insert(contours.end(), out.begin(), out.end());
        }

        // 2) Offset the holes one by one, collect the results.
        {
            for (Polygons::const_iterator it_hole = it_expoly->holes.begin(); it_hole != it_expoly->holes.end(); ++ it_hole) {
                ClipperLib::Path input;
                Slic3rMultiPoint_to_ClipperPath_reversed(*it_hole, &input);
                scaleClipperPolygon(input);
                ClipperLib::ClipperOffset co;
                if (joinType == jtRound)
                    co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
                else
                    co.MiterLimit = miterLimit;
                co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
                ClipperLib::Paths out;
                co.Execute(out, - delta_scaled);
                holes.insert(holes.end(), out.begin(), out.end());
            }
        }
    }

    // 3) Subtract holes from the contours.
    ClipperLib::Paths output;
    {
        ClipperLib::Clipper clipper;
        clipper.Clear();
        clipper.AddPaths(contours, ClipperLib::ptSubject, true);
        clipper.AddPaths(holes, ClipperLib::ptClip, true);
        clipper.Execute(ClipperLib::ctDifference, *retval, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
    }
    
    // 4) Unscale the output.
    unscaleClipperPolygons(*retval);
}

    bool validate() const
    {
        mapnik::geometry::geometry<double> geom;
        if (!mapnik::from_wkt(wkt_in_, geom))
        {
            throw std::runtime_error("Failed to parse WKT");
        }
        if (mapnik::geometry::is_empty(geom))
        {
            std::clog << "empty geom!\n";
            return false;
        }
        if (!geom.is<mapnik::geometry::polygon<double> >())
        {
            std::clog << "not a polygon!\n";
            return false;
        }
        mapnik::geometry::polygon<double> & poly = mapnik::util::get<mapnik::geometry::polygon<double> >(geom);
        mapnik::geometry::correct(poly);
        ClipperLib::Clipper clipper;

        mapnik::geometry::line_string<std::int64_t> path;
        for (auto const& pt : poly.exterior_ring)
        {
            double x = pt.x;
            double y = pt.y;
            path.emplace_back(static_cast<ClipperLib::cInt>(x),static_cast<ClipperLib::cInt>(y));
        }
        if (!clipper.AddPath(path, ClipperLib::ptSubject, true))
        {
            std::clog << "ptSubject ext failed!\n";
        }
        for (auto const& ring : poly.interior_rings)
        {
            path.clear();
            for (auto const& pt : ring)
            {
                double x = pt.x;
                double y = pt.y;
                path.emplace_back(static_cast<ClipperLib::cInt>(x),static_cast<ClipperLib::cInt>(y));
            }
            if (!clipper.AddPath(path, ClipperLib::ptSubject, true))
            {
                std::clog << "ptSubject ext failed!\n";
            }
        }
        std::cerr << "path size=" << path.size() << std::endl;
        mapnik::geometry::line_string<std::int64_t> clip_box;
        clip_box.emplace_back(static_cast<ClipperLib::cInt>(extent_.minx()),static_cast<ClipperLib::cInt>(extent_.miny()));
        clip_box.emplace_back(static_cast<ClipperLib::cInt>(extent_.maxx()),static_cast<ClipperLib::cInt>(extent_.miny()));
        clip_box.emplace_back(static_cast<ClipperLib::cInt>(extent_.maxx()),static_cast<ClipperLib::cInt>(extent_.maxy()));
        clip_box.emplace_back(static_cast<ClipperLib::cInt>(extent_.minx()),static_cast<ClipperLib::cInt>(extent_.maxy()));
        clip_box.emplace_back(static_cast<ClipperLib::cInt>(extent_.minx()),static_cast<ClipperLib::cInt>(extent_.miny()));

        if (!clipper.AddPath( clip_box, ClipperLib::ptClip, true ))
        {
            std::clog << "ptClip failed!\n";
        }

        ClipperLib::PolyTree polygons;
        clipper.Execute(ClipperLib::ctIntersection, polygons, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
        clipper.Clear();
        ClipperLib::PolyNode* polynode = polygons.GetFirst();
        mapnik::geometry::multi_polygon<double> mp;
        mp.emplace_back();
        bool first = true;
        while (polynode)
        {
            if (!polynode->IsHole())
            {
                if (first) first = false;
                else mp.emplace_back(); // start new polygon
                for (auto const& pt : polynode->Contour)
                {
                    mp.back().exterior_ring.add_coord(pt.x, pt.y);
                }
                // childrens are interior rings
                for (auto const* ring : polynode->Childs)
                {
                    mapnik::geometry::linear_ring<double> hole;
                    for (auto const& pt : ring->Contour)
                    {
                        hole.add_coord(pt.x, pt.y);
                    }
                    mp.back().add_hole(std::move(hole));
                }
            }
            polynode = polynode->GetNext();
        }
        std::string expect = expected_+".png";
        std::string actual = expected_+"_actual.png";
        mapnik::geometry::geometry<double> geom2(mp);
        auto env = mapnik::geometry::envelope(geom2);
        if (!mapnik::util::exists(expect) || (std::getenv("UPDATE") != nullptr))
        {
            std::clog << "generating expected image: " << expect << "\n";
            render(mp,env,expect);
        }
        render(mp,env,actual);
        return benchmark::compare_images(actual,expect);
//.........这里部分代码省略.........