Elephant foot compensation: Refactored / simplified,
fixed an error for variable ExPolygon expansion (not used in production code yet), fixed asserts when expanding a hole produces a hole in hole, which is a valid situation.
This commit is contained in:
Vojtech Bubnik
parent
54db40eae2
commit
bd301d2a85
2 changed files with 139 additions and 131 deletions
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@ -1,6 +1,7 @@
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#include "ClipperUtils.hpp"
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#include "Geometry.hpp"
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#include "ShortestPath.hpp"
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#include "Utils.hpp"
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// #define CLIPPER_UTILS_DEBUG
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@ -1167,34 +1168,45 @@ ClipperLib::Path mittered_offset_path_scaled(const Points &contour, const std::v
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return out;
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}
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Polygons variable_offset_inner(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit)
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static void variable_offset_inner_raw(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit, ClipperLib::Paths &contours, ClipperLib::Paths &holes)
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{
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#ifndef NDEBUG
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// Verify that the deltas are all non positive.
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for (const std::vector<float> &ds : deltas)
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for (float delta : ds)
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assert(delta <= 0.);
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assert(expoly.holes.size() + 1 == deltas.size());
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// Verify that the deltas are all non positive.
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for (const std::vector<float> &ds : deltas)
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for (float delta : ds)
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assert(delta <= 0.);
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assert(expoly.holes.size() + 1 == deltas.size());
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assert(ClipperLib::Area(expoly.contour.points) > 0.);
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for (auto &h : expoly.holes)
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assert(ClipperLib::Area(h.points) < 0.);
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#endif /* NDEBUG */
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// 1) Offset the outer contour.
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ClipperLib::Paths contours = fix_after_inner_offset(mittered_offset_path_scaled(expoly.contour.points, deltas.front(), miter_limit), ClipperLib::pftNegative, true);
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#ifndef NDEBUG
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for (auto &c : contours)
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assert(ClipperLib::Area(c) > 0.);
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// 1) Offset the outer contour.
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contours = fix_after_inner_offset(mittered_offset_path_scaled(expoly.contour.points, deltas.front(), miter_limit), ClipperLib::pftNegative, true);
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#ifndef NDEBUG
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// Shrinking a contour may split it into pieces, but never create a new hole inside the contour.
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for (auto &c : contours)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 2) Offset the holes one by one, collect the results.
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ClipperLib::Paths holes;
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holes.reserve(expoly.holes.size());
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for (const Polygon& hole : expoly.holes)
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append(holes, fix_after_outer_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftNegative, false));
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#ifndef NDEBUG
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for (auto &c : holes)
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assert(ClipperLib::Area(c) > 0.);
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// 2) Offset the holes one by one, collect the results.
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holes.reserve(expoly.holes.size());
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for (const Polygon &hole : expoly.holes)
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append(holes, fix_after_outer_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftNegative, false));
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#ifndef NDEBUG
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// Offsetting a hole curve of a C shape may close the C into a ring with a new hole inside, thus creating a hole inside a hole shape, thus a hole will be created with negative area
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// and the following test will fail.
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// for (auto &c : holes)
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// assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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}
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// 3) Subtract holes from the contours.
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Polygons variable_offset_inner(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit)
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{
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ClipperLib::Paths contours, holes;
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variable_offset_inner_raw(expoly, deltas, miter_limit, contours, holes);
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// Subtract holes from the contours.
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ClipperLib::Paths output;
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if (holes.empty())
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output = std::move(contours);
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@ -1202,6 +1214,8 @@ Polygons variable_offset_inner(const ExPolygon &expoly, const std::vector<std::v
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ClipperLib::Clipper clipper;
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clipper.Clear();
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clipper.AddPaths(contours, ClipperLib::ptSubject, true);
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// Holes may contain holes in holes produced by expanding a C hole shape.
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// The situation is processed correctly by Clipper diff operation.
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clipper.AddPaths(holes, ClipperLib::ptClip, true);
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clipper.Execute(ClipperLib::ctDifference, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
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}
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@ -1209,129 +1223,120 @@ Polygons variable_offset_inner(const ExPolygon &expoly, const std::vector<std::v
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return to_polygons(std::move(output));
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}
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ExPolygons variable_offset_inner_ex(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit)
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{
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ClipperLib::Paths contours, holes;
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variable_offset_inner_raw(expoly, deltas, miter_limit, contours, holes);
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// Subtract holes from the contours.
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ExPolygons output;
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if (holes.empty()) {
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output.reserve(contours.size());
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// Shrinking a CCW contour may only produce more CCW contours, but never new holes.
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for (ClipperLib::Path &path : contours)
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output.emplace_back(std::move(path));
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} else {
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ClipperLib::Clipper clipper;
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clipper.AddPaths(contours, ClipperLib::ptSubject, true);
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// Holes may contain holes in holes produced by expanding a C hole shape.
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// The situation is processed correctly by Clipper diff operation, producing concentric expolygons.
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clipper.AddPaths(holes, ClipperLib::ptClip, true);
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ClipperLib::PolyTree polytree;
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clipper.Execute(ClipperLib::ctDifference, polytree, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
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output = PolyTreeToExPolygons(std::move(polytree));
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}
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return output;
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}
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static void variable_offset_outer_raw(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit, ClipperLib::Paths &contours, ClipperLib::Paths &holes)
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{
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#ifndef NDEBUG
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// Verify that the deltas are all non positive.
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for (const std::vector<float> &ds : deltas)
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for (float delta : ds)
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assert(delta >= 0.);
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assert(expoly.holes.size() + 1 == deltas.size());
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assert(ClipperLib::Area(expoly.contour.points) > 0.);
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for (auto &h : expoly.holes)
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assert(ClipperLib::Area(h.points) < 0.);
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#endif /* NDEBUG */
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// 1) Offset the outer contour.
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contours = fix_after_outer_offset(mittered_offset_path_scaled(expoly.contour.points, deltas.front(), miter_limit), ClipperLib::pftPositive, false);
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// Inflating a contour must not remove it.
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assert(contours.size() >= 1);
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#ifndef NDEBUG
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// Offsetting a positive curve of a C shape may close the C into a ring with hole shape, thus a hole will be created with negative area
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// and the following test will fail.
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// for (auto &c : contours)
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// assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 2) Offset the holes one by one, collect the results.
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holes.reserve(expoly.holes.size());
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for (const Polygon& hole : expoly.holes)
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append(holes, fix_after_inner_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftPositive, true));
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#ifndef NDEBUG
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// Shrinking a hole may split it into pieces, but never create a new hole inside a hole.
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for (auto &c : holes)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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}
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Polygons variable_offset_outer(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit)
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{
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#ifndef NDEBUG
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// Verify that the deltas are all non positive.
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for (const std::vector<float>& ds : deltas)
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for (float delta : ds)
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assert(delta >= 0.);
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assert(expoly.holes.size() + 1 == deltas.size());
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#endif /* NDEBUG */
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ClipperLib::Paths contours, holes;
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variable_offset_outer_raw(expoly, deltas, miter_limit, contours, holes);
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// 1) Offset the outer contour.
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ClipperLib::Paths contours = fix_after_outer_offset(mittered_offset_path_scaled(expoly.contour.points, deltas.front(), miter_limit), ClipperLib::pftPositive, false);
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#ifndef NDEBUG
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for (auto &c : contours)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// Subtract holes from the contours.
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ClipperLib::Paths output;
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if (holes.empty())
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output = std::move(contours);
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else {
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//FIXME the difference is not needed as the holes may never intersect with other holes.
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ClipperLib::Clipper clipper;
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clipper.Clear();
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clipper.AddPaths(contours, ClipperLib::ptSubject, true);
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clipper.AddPaths(holes, ClipperLib::ptClip, true);
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clipper.Execute(ClipperLib::ctDifference, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
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}
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// 2) Offset the holes one by one, collect the results.
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ClipperLib::Paths holes;
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holes.reserve(expoly.holes.size());
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for (const Polygon& hole : expoly.holes)
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append(holes, fix_after_inner_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftPositive, true));
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#ifndef NDEBUG
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for (auto &c : holes)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 3) Subtract holes from the contours.
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ClipperLib::Paths output;
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if (holes.empty())
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output = std::move(contours);
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else {
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ClipperLib::Clipper clipper;
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clipper.Clear();
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clipper.AddPaths(contours, ClipperLib::ptSubject, true);
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clipper.AddPaths(holes, ClipperLib::ptClip, true);
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clipper.Execute(ClipperLib::ctDifference, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
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}
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return to_polygons(std::move(output));
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return to_polygons(std::move(output));
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}
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ExPolygons variable_offset_outer_ex(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit)
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{
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#ifndef NDEBUG
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// Verify that the deltas are all non positive.
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for (const std::vector<float>& ds : deltas)
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for (float delta : ds)
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assert(delta >= 0.);
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assert(expoly.holes.size() + 1 == deltas.size());
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#endif /* NDEBUG */
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ClipperLib::Paths contours, holes;
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variable_offset_outer_raw(expoly, deltas, miter_limit, contours, holes);
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// 1) Offset the outer contour.
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ClipperLib::Paths contours = fix_after_outer_offset(mittered_offset_path_scaled(expoly.contour.points, deltas.front(), miter_limit), ClipperLib::pftPositive, false);
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#ifndef NDEBUG
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for (auto &c : contours)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 2) Offset the holes one by one, collect the results.
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ClipperLib::Paths holes;
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holes.reserve(expoly.holes.size());
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for (const Polygon& hole : expoly.holes)
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append(holes, fix_after_inner_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftPositive, true));
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#ifndef NDEBUG
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for (auto &c : holes)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 3) Subtract holes from the contours.
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// Subtract holes from the contours.
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ExPolygons output;
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if (holes.empty()) {
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output.reserve(contours.size());
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for (ClipperLib::Path &path : contours)
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output.emplace_back(std::move(path));
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} else {
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ClipperLib::Clipper clipper;
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clipper.AddPaths(contours, ClipperLib::ptSubject, true);
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clipper.AddPaths(holes, ClipperLib::ptClip, true);
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ClipperLib::PolyTree polytree;
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clipper.Execute(ClipperLib::ctDifference, polytree, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
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output = PolyTreeToExPolygons(std::move(polytree));
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}
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return output;
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}
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ExPolygons variable_offset_inner_ex(const ExPolygon &expoly, const std::vector<std::vector<float>> &deltas, double miter_limit)
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{
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#ifndef NDEBUG
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// Verify that the deltas are all non positive.
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for (const std::vector<float>& ds : deltas)
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for (float delta : ds)
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assert(delta <= 0.);
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assert(expoly.holes.size() + 1 == deltas.size());
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#endif /* NDEBUG */
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// 1) Offset the outer contour.
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ClipperLib::Paths contours = fix_after_inner_offset(mittered_offset_path_scaled(expoly.contour.points, deltas.front(), miter_limit), ClipperLib::pftNegative, true);
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#ifndef NDEBUG
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for (auto &c : contours)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 2) Offset the holes one by one, collect the results.
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ClipperLib::Paths holes;
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holes.reserve(expoly.holes.size());
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for (const Polygon& hole : expoly.holes)
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append(holes, fix_after_outer_offset(mittered_offset_path_scaled(hole.points, deltas[1 + &hole - expoly.holes.data()], miter_limit), ClipperLib::pftNegative, false));
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#ifndef NDEBUG
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for (auto &c : holes)
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assert(ClipperLib::Area(c) > 0.);
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#endif /* NDEBUG */
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// 3) Subtract holes from the contours.
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ExPolygons output;
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if (holes.empty()) {
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output.reserve(contours.size());
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for (ClipperLib::Path &path : contours)
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output.emplace_back(std::move(path));
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output.reserve(1);
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if (contours.size() > 1) {
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// One expolygon with holes created by closing a C shape. Which is which?
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output.push_back({});
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ExPolygon &out = output.back();
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out.holes.reserve(contours.size() - 1);
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for (ClipperLib::Path &path : contours) {
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if (ClipperLib::Area(path) > 0) {
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// Only one contour with positive area is expected to be created by an outer offset of an ExPolygon.
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assert(out.contour.empty());
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out.contour.points = std::move(path);
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} else
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out.holes.push_back(Polygon{ std::move(path) });
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}
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} else {
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// Single contour must be CCW.
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assert(contours.size() == 1);
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assert(ClipperLib::Area(contours.front()) > 0);
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output.push_back(ExPolygon{ std::move(contours.front()) });
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}
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} else {
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//FIXME the difference is not needed as the holes may never intersect with other holes.
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ClipperLib::Clipper clipper;
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// Contours may have holes if they were created by closing a C shape.
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clipper.AddPaths(contours, ClipperLib::ptSubject, true);
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clipper.AddPaths(holes, ClipperLib::ptClip, true);
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ClipperLib::PolyTree polytree;
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@ -1339,6 +1344,7 @@ ExPolygons variable_offset_inner_ex(const ExPolygon &expoly, const std::vector<s
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output = PolyTreeToExPolygons(std::move(polytree));
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}
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assert(output.size() == 1);
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return output;
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}
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@ -597,7 +597,8 @@ ExPolygon elephant_foot_compensation(const ExPolygon &input_expoly, double min_c
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}
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ExPolygons out_vec = variable_offset_inner_ex(resampled, deltas, 2.);
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if (out_vec.size() == 1)
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if (out_vec.size() == 1 && out_vec.front().holes.size() == resampled.holes.size())
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// No contour of the original compensated expolygon was lost.
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out = std::move(out_vec.front());
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else {
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// Something went wrong, don't compensate.
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@ -610,6 +611,7 @@ ExPolygon elephant_foot_compensation(const ExPolygon &input_expoly, double min_c
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{ { out_vec }, { "gray", "black", "blue", coord_t(scale_(0.02)), 0.5f, "black", coord_t(scale_(0.05)) } } });
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}
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#endif /* TESTS_EXPORT_SVGS */
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// It may be that the source expolygons contained non-manifold vertices, for which the variable offset may not produce the same number of contours or holes.
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assert(out_vec.size() == 1);
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}
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}
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