3DPrinting/PrusaSlicer-NonPlainar
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Fix of Layer::build_up_down_graph() for non-manifold inputs

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by shrinking the input expolygons before intersecting them.
GH #10150, #10158, SPE-1621, SPE-1612
This commit is contained in:
Vojtech Bubnik 2023-04-12 17:02:52 +02:00
parent d3d48e9895
commit bceed00ae8
1 changed files with 60 additions and 19 deletions
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79
src/libslic3r/Layer.cpp
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@ -60,7 +60,10 @@ void Layer::make_slices()
}
// used by Layer::build_up_down_graph()
[[nodiscard]] static ClipperLib_Z::Paths expolygons_to_zpaths(const ExPolygons &expolygons, coord_t isrc)
// Shrink source polygons one by one, so that they will be separated if they were touching
// at vertices (non-manifold situation).
// Then convert them to Z-paths with Z coordinate indicating index of the source expolygon.
[[nodiscard]] static ClipperLib_Z::Paths expolygons_to_zpaths_shrunk(const ExPolygons &expolygons, coord_t isrc)
{
size_t num_paths = 0;
for (const ExPolygon &expolygon : expolygons)
@ -69,14 +72,49 @@ void Layer::make_slices()
ClipperLib_Z::Paths out;
out.reserve(num_paths);
for (const ExPolygon &expolygon : expolygons) {
for (size_t icontour = 0; icontour < expolygon.num_contours(); ++ icontour) {
const Polygon &contour = expolygon.contour_or_hole(icontour);
out.emplace_back();
ClipperLib_Z::Path &path = out.back();
path.reserve(contour.size());
for (const Point &p : contour.points)
path.push_back({ p.x(), p.y(), isrc });
ClipperLib::Paths contours;
ClipperLib::Paths holes;
ClipperLib::Clipper clipper;
ClipperLib::ClipperOffset co;
ClipperLib::Paths out2;
static constexpr const float delta = ClipperSafetyOffset; // *10.f;
co.MiterLimit = scaled<double>(3.);
// Use the default zero edge merging distance. For this kind of safety offset the accuracy of normal direction is not important.
// co.ShortestEdgeLength = delta * ClipperOffsetShortestEdgeFactor;
for (const ExPolygon &expoly : expolygons) {
contours.clear();
co.Clear();
co.AddPath(expoly.contour.points, ClipperLib::jtMiter, ClipperLib::etClosedPolygon);
co.Execute(contours, - delta);
if (! contours.empty()) {
holes.clear();
for (const Polygon &hole : expoly.holes) {
co.Clear();
co.AddPath(hole.points, ClipperLib::jtMiter, ClipperLib::etClosedPolygon);
// Execute reorients the contours so that the outer most contour has a positive area. Thus the output
// contours will be CCW oriented even though the input paths are CW oriented.
// Offset is applied after contour reorientation, thus the signum of the offset value is reversed.
out2.clear();
co.Execute(out2, delta);
append(holes, std::move(out2));
}
// Subtract holes from the contours.
if (! holes.empty()) {
clipper.Clear();
clipper.AddPaths(contours, ClipperLib::ptSubject, true);
clipper.AddPaths(holes, ClipperLib::ptClip, true);
contours.clear();
clipper.Execute(ClipperLib::ctDifference, contours, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
}
for (const auto &contour : contours) {
out.emplace_back();
ClipperLib_Z::Path &path = out.back();
path.reserve(contour.size());
for (const Point &p : contour)
path.push_back({ p.x(), p.y(), isrc });
}
}
++ isrc;
}
@ -183,6 +221,10 @@ static void connect_layer_slices(
break;
}
}
//FIXME remove the following block one day, it should not be needed.
// The following shall not happen now as the source expolygons are being shrunk a bit before intersecting,
// thus each point of each intersection polygon should fit completely inside one of the original (unshrunk) expolygons.
assert(found);
if (!found) {
// The check above might sometimes fail when the polygons overlap only on points, which causes the clipper to detect no intersection.
// The problem happens rarely, mostly on simple polygons (in terms of number of points), but regardless of size!
@ -191,10 +233,7 @@ static void connect_layer_slices(
// layer B = Polygon{(-24877897,-11100524),(-22504249,-8726874),(-22504249,11477151),(-23244827,12218916),(-23752371,12727276),(-25002495,12727276),(-27502745,10227026),(-27502745,-12727274),(-26504645,-12727274)}
// note that first point is not identical, and the check above picks (-24877897,-11100524) as the first contour point (polynode.Contour.front()).
// that point is sadly slightly outisde of the layer A, so no link is detected, eventhough they are overlaping "completely"
Polygon contour_poly;
for (const auto& p : polynode.Contour) {
contour_poly.points.emplace_back(p.x(), p.y());
}
Polygon contour_poly(ClipperZUtils::from_zpath(polynode.Contour));
BoundingBox contour_aabb{contour_poly.points};
for (int l = int(m_above.lslices_ex.size()) - 1; l >= 0; --l) {
LayerSlice &lslice = m_above.lslices_ex[l];
@ -222,11 +261,11 @@ static void connect_layer_slices(
break;
}
}
//FIXME remove the following block one day, it should not be needed.
// The following shall not happen now as the source expolygons are being shrunk a bit before intersecting,
// thus each point of each intersection polygon should fit completely inside one of the original (unshrunk) expolygons.
if (!found) { // Explanation for aditional check is above.
Polygon contour_poly;
for (const auto &p : polynode.Contour) {
contour_poly.points.emplace_back(p.x(), p.y());
}
Polygon contour_poly(ClipperZUtils::from_zpath(polynode.Contour));
BoundingBox contour_aabb{contour_poly.points};
for (int l = int(m_below.lslices_ex.size()) - 1; l >= 0; --l) {
LayerSlice &lslice = m_below.lslices_ex[l];
@ -249,6 +288,8 @@ static void connect_layer_slices(
found = true;
}
if (found) {
assert(i >= 0 && i < m_below.lslices_ex.size());
assert(j >= 0 && j < m_above.lslices_ex.size());
// Subtract area of holes from the area of outer contour.
double area = ClipperLib_Z::Area(polynode.Contour);
for (int icontour = 0; icontour < polynode.ChildCount(); ++ icontour)
@ -340,9 +381,9 @@ static void connect_layer_slices(
void Layer::build_up_down_graph(Layer& below, Layer& above)
{
coord_t paths_below_offset = 0;
ClipperLib_Z::Paths paths_below = expolygons_to_zpaths(below.lslices, paths_below_offset);
ClipperLib_Z::Paths paths_below = expolygons_to_zpaths_shrunk(below.lslices, paths_below_offset);
coord_t paths_above_offset = paths_below_offset + coord_t(below.lslices.size());
ClipperLib_Z::Paths paths_above = expolygons_to_zpaths(above.lslices, paths_above_offset);
ClipperLib_Z::Paths paths_above = expolygons_to_zpaths_shrunk(above.lslices, paths_above_offset);
#ifndef NDEBUG
coord_t paths_end = paths_above_offset + coord_t(above.lslices.size());
#endif // NDEBUG