7d4b3f2992
Fixes Solid infill where there should be none #6482 Also the safety offsetting was revised to be enabled only where needed, the "do safety offset" is now easy to discover by a new ApplySafetyOffset::Yes enum, and safety offset over union, which is better done by offset() / offset_ex() has been replaced with new union_safety_offset() / union_safety_offset_ex() functions, which better convey their meaning and which could be better optimized than union() with the safety offset applied.
382 lines
15 KiB
C++
382 lines
15 KiB
C++
#include "BridgeDetector.hpp"
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#include "ClipperUtils.hpp"
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#include "Geometry.hpp"
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#include <algorithm>
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namespace Slic3r {
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BridgeDetector::BridgeDetector(
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ExPolygon _expolygon,
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const ExPolygons &_lower_slices,
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coord_t _spacing) :
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// The original infill polygon, not inflated.
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expolygons(expolygons_owned),
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// All surfaces of the object supporting this region.
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lower_slices(_lower_slices),
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spacing(_spacing)
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{
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this->expolygons_owned.push_back(std::move(_expolygon));
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initialize();
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}
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BridgeDetector::BridgeDetector(
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const ExPolygons &_expolygons,
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const ExPolygons &_lower_slices,
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coord_t _spacing) :
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// The original infill polygon, not inflated.
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expolygons(_expolygons),
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// All surfaces of the object supporting this region.
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lower_slices(_lower_slices),
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spacing(_spacing)
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{
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initialize();
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}
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void BridgeDetector::initialize()
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{
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// 5 degrees stepping
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this->resolution = PI/36.0;
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// output angle not known
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this->angle = -1.;
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// Outset our bridge by an arbitrary amout; we'll use this outer margin for detecting anchors.
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Polygons grown = offset(this->expolygons, float(this->spacing));
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// Detect possible anchoring edges of this bridging region.
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// Detect what edges lie on lower slices by turning bridge contour and holes
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// into polylines and then clipping them with each lower slice's contour.
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// Currently _edges are only used to set a candidate direction of the bridge (see bridge_direction_candidates()).
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Polygons contours;
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contours.reserve(this->lower_slices.size());
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for (const ExPolygon &expoly : this->lower_slices)
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contours.push_back(expoly.contour);
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this->_edges = intersection_pl(to_polylines(grown), contours);
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#ifdef SLIC3R_DEBUG
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printf(" bridge has %zu support(s)\n", this->_edges.size());
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#endif
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// detect anchors as intersection between our bridge expolygon and the lower slices
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// safety offset required to avoid Clipper from detecting empty intersection while Boost actually found some edges
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this->_anchor_regions = intersection_ex(grown, union_safety_offset(this->lower_slices));
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/*
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if (0) {
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require "Slic3r/SVG.pm";
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Slic3r::SVG::output("bridge.svg",
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expolygons => [ $self->expolygon ],
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red_expolygons => $self->lower_slices,
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polylines => $self->_edges,
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);
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}
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*/
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}
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bool BridgeDetector::detect_angle(double bridge_direction_override)
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{
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if (this->_edges.empty() || this->_anchor_regions.empty())
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// The bridging region is completely in the air, there are no anchors available at the layer below.
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return false;
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std::vector<BridgeDirection> candidates;
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if (bridge_direction_override == 0.) {
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std::vector<double> angles = bridge_direction_candidates();
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candidates.reserve(angles.size());
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for (size_t i = 0; i < angles.size(); ++ i)
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candidates.emplace_back(BridgeDirection(angles[i]));
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} else
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candidates.emplace_back(BridgeDirection(bridge_direction_override));
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/* Outset the bridge expolygon by half the amount we used for detecting anchors;
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we'll use this one to clip our test lines and be sure that their endpoints
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are inside the anchors and not on their contours leading to false negatives. */
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Polygons clip_area = offset(this->expolygons, 0.5f * float(this->spacing));
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/* we'll now try several directions using a rudimentary visibility check:
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bridge in several directions and then sum the length of lines having both
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endpoints within anchors */
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bool have_coverage = false;
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for (size_t i_angle = 0; i_angle < candidates.size(); ++ i_angle)
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{
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const double angle = candidates[i_angle].angle;
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Lines lines;
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{
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// Get an oriented bounding box around _anchor_regions.
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BoundingBox bbox = get_extents_rotated(this->_anchor_regions, - angle);
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// Cover the region with line segments.
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lines.reserve((bbox.max(1) - bbox.min(1) + this->spacing) / this->spacing);
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double s = sin(angle);
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double c = cos(angle);
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//FIXME Vojtech: The lines shall be spaced half the line width from the edge, but then
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// some of the test cases fail. Need to adjust the test cases then?
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// for (coord_t y = bbox.min(1) + this->spacing / 2; y <= bbox.max(1); y += this->spacing)
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for (coord_t y = bbox.min(1); y <= bbox.max(1); y += this->spacing)
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lines.push_back(Line(
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Point((coord_t)round(c * bbox.min(0) - s * y), (coord_t)round(c * y + s * bbox.min(0))),
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Point((coord_t)round(c * bbox.max(0) - s * y), (coord_t)round(c * y + s * bbox.max(0)))));
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}
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double total_length = 0;
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double max_length = 0;
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{
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Lines clipped_lines = intersection_ln(lines, clip_area);
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for (size_t i = 0; i < clipped_lines.size(); ++i) {
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const Line &line = clipped_lines[i];
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if (expolygons_contain(this->_anchor_regions, line.a) && expolygons_contain(this->_anchor_regions, line.b)) {
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// This line could be anchored.
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double len = line.length();
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total_length += len;
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max_length = std::max(max_length, len);
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}
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}
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}
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if (total_length == 0.)
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continue;
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have_coverage = true;
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// Sum length of bridged lines.
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candidates[i_angle].coverage = total_length;
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/* The following produces more correct results in some cases and more broken in others.
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TODO: investigate, as it looks more reliable than line clipping. */
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// $directions_coverage{$angle} = sum(map $_->area, @{$self->coverage($angle)}) // 0;
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// max length of bridged lines
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candidates[i_angle].max_length = max_length;
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}
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// if no direction produced coverage, then there's no bridge direction
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if (! have_coverage)
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return false;
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// sort directions by coverage - most coverage first
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std::sort(candidates.begin(), candidates.end());
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// if any other direction is within extrusion width of coverage, prefer it if shorter
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// TODO: There are two options here - within width of the angle with most coverage, or within width of the currently perferred?
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size_t i_best = 0;
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for (size_t i = 1; i < candidates.size() && candidates[i_best].coverage - candidates[i].coverage < this->spacing; ++ i)
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if (candidates[i].max_length < candidates[i_best].max_length)
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i_best = i;
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this->angle = candidates[i_best].angle;
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if (this->angle >= PI)
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this->angle -= PI;
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#ifdef SLIC3R_DEBUG
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printf(" Optimal infill angle is %d degrees\n", (int)Slic3r::Geometry::rad2deg(this->angle));
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#endif
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return true;
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}
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std::vector<double> BridgeDetector::bridge_direction_candidates() const
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{
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// we test angles according to configured resolution
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std::vector<double> angles;
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for (int i = 0; i <= PI/this->resolution; ++i)
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angles.push_back(i * this->resolution);
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// we also test angles of each bridge contour
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{
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Lines lines = to_lines(this->expolygons);
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for (Lines::const_iterator line = lines.begin(); line != lines.end(); ++line)
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angles.push_back(line->direction());
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}
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/* we also test angles of each open supporting edge
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(this finds the optimal angle for C-shaped supports) */
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for (const Polyline &edge : this->_edges)
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if (edge.first_point() != edge.last_point())
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angles.push_back(Line(edge.first_point(), edge.last_point()).direction());
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// remove duplicates
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double min_resolution = PI/180.0; // 1 degree
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std::sort(angles.begin(), angles.end());
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for (size_t i = 1; i < angles.size(); ++i) {
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if (Slic3r::Geometry::directions_parallel(angles[i], angles[i-1], min_resolution)) {
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angles.erase(angles.begin() + i);
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--i;
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}
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}
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/* compare first value with last one and remove the greatest one (PI)
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in case they are parallel (PI, 0) */
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if (Slic3r::Geometry::directions_parallel(angles.front(), angles.back(), min_resolution))
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angles.pop_back();
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return angles;
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}
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/*
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static void get_trapezoids(const ExPolygon &expoly, Polygons* polygons) const
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{
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ExPolygons expp;
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expp.push_back(expoly);
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boost::polygon::get_trapezoids(*polygons, expp);
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}
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void ExPolygon::get_trapezoids(ExPolygon clone, Polygons* polygons, double angle) const
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{
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clone.rotate(PI/2 - angle, Point(0,0));
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clone.get_trapezoids(polygons);
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for (Polygons::iterator polygon = polygons->begin(); polygon != polygons->end(); ++polygon)
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polygon->rotate(-(PI/2 - angle), Point(0,0));
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}
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*/
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// This algorithm may return more trapezoids than necessary
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// (i.e. it may break a single trapezoid in several because
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// other parts of the object have x coordinates in the middle)
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static void get_trapezoids2(const ExPolygon& expoly, Polygons* polygons)
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{
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Polygons src_polygons = to_polygons(expoly);
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// get all points of this ExPolygon
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const Points pp = to_points(src_polygons);
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// build our bounding box
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BoundingBox bb(pp);
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// get all x coordinates
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std::vector<coord_t> xx;
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xx.reserve(pp.size());
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for (Points::const_iterator p = pp.begin(); p != pp.end(); ++p)
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xx.push_back(p->x());
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std::sort(xx.begin(), xx.end());
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// find trapezoids by looping from first to next-to-last coordinate
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Polygons rectangle;
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rectangle.emplace_back(Polygon());
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for (std::vector<coord_t>::const_iterator x = xx.begin(); x != xx.end()-1; ++x) {
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coord_t next_x = *(x + 1);
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if (*x != next_x) {
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// intersect with rectangle
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// append results to return value
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rectangle.front() = { { *x, bb.min.y() }, { next_x, bb.min.y() }, { next_x, bb.max.y() }, { *x, bb.max.y() } };
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polygons_append(*polygons, intersection(rectangle, src_polygons));
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}
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}
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}
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static void get_trapezoids2(const ExPolygon &expoly, Polygons* polygons, double angle)
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{
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ExPolygon clone = expoly;
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clone.rotate(PI/2 - angle, Point(0,0));
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get_trapezoids2(clone, polygons);
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for (Polygon &polygon : *polygons)
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polygon.rotate(-(PI/2 - angle), Point(0,0));
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}
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// Coverage is currently only used by the unit tests. It is extremely slow and unreliable!
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Polygons BridgeDetector::coverage(double angle) const
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{
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if (angle == -1)
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angle = this->angle;
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Polygons covered;
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if (angle != -1) {
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// Get anchors, convert them to Polygons and rotate them.
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Polygons anchors = to_polygons(this->_anchor_regions);
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polygons_rotate(anchors, PI/2.0 - angle);
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for (ExPolygon expolygon : this->expolygons) {
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// Clone our expolygon and rotate it so that we work with vertical lines.
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expolygon.rotate(PI/2.0 - angle);
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// Outset the bridge expolygon by half the amount we used for detecting anchors;
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// we'll use this one to generate our trapezoids and be sure that their vertices
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// are inside the anchors and not on their contours leading to false negatives.
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for (ExPolygon &expoly : offset_ex(expolygon, 0.5f * float(this->spacing))) {
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// Compute trapezoids according to a vertical orientation
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Polygons trapezoids;
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get_trapezoids2(expoly, &trapezoids, PI/2.0);
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for (const Polygon &trapezoid : trapezoids) {
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// not nice, we need a more robust non-numeric check
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size_t n_supported = 0;
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for (const Line &supported_line : intersection_ln(trapezoid.lines(), anchors))
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if (supported_line.length() >= this->spacing)
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++ n_supported;
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if (n_supported >= 2)
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covered.push_back(std::move(trapezoid));
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}
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}
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}
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// Unite the trapezoids before rotation, as the rotation creates tiny gaps and intersections between the trapezoids
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// instead of exact overlaps.
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covered = union_(covered);
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// Intersect trapezoids with actual bridge area to remove extra margins and append it to result.
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polygons_rotate(covered, -(PI/2.0 - angle));
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covered = intersection(this->expolygons, covered);
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#if 0
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{
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my @lines = map @{$_->lines}, @$trapezoids;
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$_->rotate(-(PI/2 - $angle), [0,0]) for @lines;
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require "Slic3r/SVG.pm";
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Slic3r::SVG::output(
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"coverage_" . rad2deg($angle) . ".svg",
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expolygons => [$self->expolygon],
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green_expolygons => $self->_anchor_regions,
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red_expolygons => $coverage,
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lines => \@lines,
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);
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}
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#endif
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}
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return covered;
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}
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/* This method returns the bridge edges (as polylines) that are not supported
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but would allow the entire bridge area to be bridged with detected angle
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if supported too */
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void
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BridgeDetector::unsupported_edges(double angle, Polylines* unsupported) const
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{
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if (angle == -1) angle = this->angle;
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if (angle == -1) return;
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Polygons grown_lower = offset(this->lower_slices, float(this->spacing));
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for (ExPolygons::const_iterator it_expoly = this->expolygons.begin(); it_expoly != this->expolygons.end(); ++ it_expoly) {
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// get unsupported bridge edges (both contour and holes)
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Lines unsupported_lines = to_lines(diff_pl(to_polylines(*it_expoly), grown_lower));
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/* Split into individual segments and filter out edges parallel to the bridging angle
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TODO: angle tolerance should probably be based on segment length and flow width,
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so that we build supports whenever there's a chance that at least one or two bridge
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extrusions would be anchored within such length (i.e. a slightly non-parallel bridging
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direction might still benefit from anchors if long enough)
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double angle_tolerance = PI / 180.0 * 5.0; */
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for (const Line &line : unsupported_lines)
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if (! Slic3r::Geometry::directions_parallel(line.direction(), angle)) {
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unsupported->emplace_back(Polyline());
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unsupported->back().points.emplace_back(line.a);
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unsupported->back().points.emplace_back(line.b);
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}
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}
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/*
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if (0) {
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require "Slic3r/SVG.pm";
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Slic3r::SVG::output(
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"unsupported_" . rad2deg($angle) . ".svg",
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expolygons => [$self->expolygon],
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green_expolygons => $self->_anchor_regions,
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red_expolygons => union_ex($grown_lower),
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no_arrows => 1,
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polylines => \@bridge_edges,
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red_polylines => $unsupported,
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);
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}
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*/
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}
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Polylines
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BridgeDetector::unsupported_edges(double angle) const
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{
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Polylines pp;
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this->unsupported_edges(angle, &pp);
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return pp;
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}
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}
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