PrusaSlicer/src/libslic3r/Fill/FillPlanePath.cpp

#include "../ClipperUtils.hpp"
#include "../ShortestPath.hpp"
#include "../Surface.hpp"

#include "FillPlanePath.hpp"

namespace Slic3r {

void FillPlanePath::_fill_surface_single(
    const FillParams                &params, 
    unsigned int                     thickness_layers,
    const std::pair<float, Point>   &direction, 
    ExPolygon                       &expolygon, 
    Polylines                       &polylines_out)
{
    expolygon.rotate(- direction.first);

	coord_t distance_between_lines = coord_t(scale_(this->spacing) / params.density);
    
    // align infill across layers using the object's bounding box
    // Rotated bounding box of the whole object.
    BoundingBox bounding_box = this->bounding_box.rotated(- direction.first);
    
    Point shift = this->_centered() ? 
        bounding_box.center() :
        bounding_box.min;
    expolygon.translate(-shift.x(), -shift.y());
    bounding_box.translate(-shift.x(), -shift.y());

    Pointfs pts = _generate(
        coord_t(ceil(coordf_t(bounding_box.min.x()) / distance_between_lines)),
        coord_t(ceil(coordf_t(bounding_box.min.y()) / distance_between_lines)),
        coord_t(ceil(coordf_t(bounding_box.max.x()) / distance_between_lines)),
        coord_t(ceil(coordf_t(bounding_box.max.y()) / distance_between_lines)));

    Polylines polylines;
    if (pts.size() >= 2) {
        // Convert points to a polyline, upscale.
        polylines.push_back(Polyline());
        Polyline &polyline = polylines.back();
        polyline.points.reserve(pts.size());
        for (const Vec2d &pt : pts)
            polyline.points.push_back(Point(
                coord_t(floor(pt.x() * distance_between_lines + 0.5)), 
                coord_t(floor(pt.y() * distance_between_lines + 0.5))));
//      intersection(polylines_src, offset((Polygons)expolygon, scale_(0.02)), &polylines);
        polylines = intersection_pl(std::move(polylines), to_polygons(expolygon));
        Polylines chained;
        if (params.dont_connect || params.density > 0.5 || polylines.size() <= 1)
            chained = chain_polylines(std::move(polylines));
        else
            connect_infill(std::move(polylines), expolygon, chained, this->spacing, params);
        // paths must be repositioned and rotated back
        for (Polyline &pl : chained) {
            pl.translate(shift.x(), shift.y());
            pl.rotate(direction.first);
        }
        append(polylines_out, std::move(chained));
    }
}

// Follow an Archimedean spiral, in polar coordinates: r=a+b\theta
Pointfs FillArchimedeanChords::_generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y)
{
    // Radius to achieve.
    coordf_t rmax = std::sqrt(coordf_t(max_x)*coordf_t(max_x)+coordf_t(max_y)*coordf_t(max_y)) * std::sqrt(2.) + 1.5;
    // Now unwind the spiral.
    coordf_t a = 1.;
    coordf_t b = 1./(2.*M_PI);
    coordf_t theta = 0.;
    coordf_t r = 1;
    Pointfs out;
    //FIXME Vojtech: If used as a solid infill, there is a gap left at the center.
    out.emplace_back(0, 0);
    out.emplace_back(1, 0);
    while (r < rmax) {
        // Discretization angle to achieve a discretization error lower than RESOLUTION.
        theta += 2. * acos(1. - RESOLUTION / r);
        r = a + b * theta;
        out.emplace_back(r * cos(theta), r * sin(theta));
    }
    return out;
}

// Adapted from 
// http://cpansearch.perl.org/src/KRYDE/Math-PlanePath-122/lib/Math/PlanePath/HilbertCurve.pm
//
// state=0    3--2   plain
//               |
//            0--1
//
// state=4    1--2  transpose
//            |  |
//            0  3
//
// state=8
//
// state=12   3  0  rot180 + transpose
//            |  |
//            2--1
//
static inline Point hilbert_n_to_xy(const size_t n)
{
    static const int next_state[16] = { 4,0,0,12, 0,4,4,8, 12,8,8,4, 8,12,12,0 };
    static const int digit_to_x[16] = { 0,1,1,0, 0,0,1,1, 1,0,0,1, 1,1,0,0 };
    static const int digit_to_y[16] = { 0,0,1,1, 0,1,1,0, 1,1,0,0, 1,0,0,1 };

    // Number of 2 bit digits.
    size_t ndigits = 0;
    {
        size_t nc = n;
        while(nc > 0) {
            nc >>= 2;
            ++ ndigits;
        }
    }
    int state = (ndigits & 1) ? 4 : 0;
    coord_t x = 0;
    coord_t y = 0;
    for (int i = (int)ndigits - 1; i >= 0; -- i) {
        int digit = (n >> (i * 2)) & 3;
        state += digit;
        x |= digit_to_x[state] << i;
        y |= digit_to_y[state] << i;
        state = next_state[state];
    }
    return Point(x, y);
}

Pointfs FillHilbertCurve::_generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y)
{
    // Minimum power of two square to fit the domain.
    size_t sz = 2;
    size_t pw = 1;
    {
        size_t sz0 = std::max(max_x + 1 - min_x, max_y + 1 - min_y);
        while (sz < sz0) {
            sz = sz << 1;
            ++ pw;
        }
    }

    size_t sz2 = sz * sz;
    Pointfs line;
    line.reserve(sz2);
    for (size_t i = 0; i < sz2; ++ i) {
        Point p = hilbert_n_to_xy(i);
        line.emplace_back(p.x() + min_x, p.y() + min_y);
    }
    return line;
}

Pointfs FillOctagramSpiral::_generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y)
{
    // Radius to achieve.
    coordf_t rmax = std::sqrt(coordf_t(max_x)*coordf_t(max_x)+coordf_t(max_y)*coordf_t(max_y)) * std::sqrt(2.) + 1.5;
    // Now unwind the spiral.
    coordf_t r = 0;
    coordf_t r_inc = sqrt(2.);
    Pointfs out;
    out.emplace_back(0., 0.);
    while (r < rmax) {
        r += r_inc;
        coordf_t rx = r / sqrt(2.);
        coordf_t r2 = r + rx;
        out.emplace_back( r,  0.);
        out.emplace_back( r2, rx);
        out.emplace_back( rx, rx);
        out.emplace_back( rx, r2);
        out.emplace_back( 0.,  r);
        out.emplace_back(-rx, r2);
        out.emplace_back(-rx, rx);
        out.emplace_back(-r2, rx);
        out.emplace_back(- r, 0.);
        out.emplace_back(-r2, -rx);
        out.emplace_back(-rx, -rx);
        out.emplace_back(-rx, -r2);
        out.emplace_back( 0., -r);
        out.emplace_back( rx, -r2);
        out.emplace_back( rx, -rx);
        out.emplace_back( r2+r_inc, -rx);
    }
    return out;
}

} // namespace Slic3r