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A few test cases for Voronoi diagrams.

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A few test cases collected from multi-material segmentation. All new test cases are suppressed not to fail a building process.
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Lukáš Hejl 2021-04-05 16:47:00 +02:00
parent 04526d5c28
commit 7bd412a2ca
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237
tests/libslic3r/test_voronoi.cpp
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@ -7,6 +7,7 @@
#include <libslic3r/Geometry.hpp> #include <libslic3r/Geometry.hpp>
#include <libslic3r/VoronoiOffset.hpp> #include <libslic3r/VoronoiOffset.hpp>
#include <libslic3r/VoronoiVisualUtils.hpp>
#include <numeric> #include <numeric>
@ -1922,3 +1923,239 @@ TEST_CASE("Voronoi skeleton", "[VoronoiSkeleton]")
REQUIRE(! skeleton_edges.empty()); REQUIRE(! skeleton_edges.empty());
} }
// Simple detection with complexity N^2 if there is any point in the input polygons that doesn't have Voronoi vertex.
[[maybe_unused]] static bool has_missing_voronoi_vertices(const Polygons &polygons, const VD &vd)
{
auto are_equal = [](const VD::vertex_type v, const Point &p) { return (Vec2d(v.x(), v.y()) - p.cast<double>()).norm() <= SCALED_EPSILON; };
Points poly_points = to_points(polygons);
std::vector<bool> found_vertices(poly_points.size());
for (const Point &point : poly_points)
for (const auto &vertex : vd.vertices())
if (are_equal(vertex, point)) {
found_vertices[&point - &poly_points.front()] = true;
break;
}
return std::find(found_vertices.begin(), found_vertices.end(), false) != found_vertices.end();
}
// This case is composed of one square polygon, and one of the edges is divided into two parts by a point that lies on this edge.
// In some applications, this point is unnecessary and can be removed (merge two parts to one edge). But for the case of
// multi-material segmentation, these points are necessary. In this case, Voronoi vertex for the point, which divides the edge
// into two parts. Even we add more points to the edge, and then for these points, the Voronoin vertex is also missing. An
// infinity-edge passes through the missing Voronoi vertex. Therefore, this missing Voronoi vertex and edge can be reconstructed
// using the intersection between the infinity-edge with the input polygon.
// Rotation of the polygon solves this problem.
TEST_CASE("Voronoi missing vertex 1", "[VoronoiMissingVertex1]")
{
REQUIRE(false);
Polygon poly = {
{ 25000000, 25000000},
{-25000000, 25000000},
{-25000000, -25000000},
{-12412500, -25000000},
// {- 1650000, -25000000},
{ 25000000, -25000000}
};
// poly.rotate(PI / 6);
REQUIRE(poly.area() > 0.);
REQUIRE(intersecting_edges({poly}).empty());
VD vd;
Lines lines = to_lines(poly);
construct_voronoi(lines.begin(), lines.end(), &vd);
#ifdef VORONOI_DEBUG_OUT
dump_voronoi_to_svg(debug_out_path("voronoi-missing-vertex1-out.svg").c_str(), vd, Points(), lines);
#endif
// REQUIRE(!has_missing_voronoi_vertices({poly}, vd));
}
// This case is composed of two square polygons (contour and hole), and again one of the edges is divided into two parts by a
// point that lies on this edge, and for this point is Voronoi vertex missing. A difference between the previous and this case is
// that for this case, through the missing Voronoi vertex is passing a finite edge between two internal Voronoin vertices.
// Therefore, this missing Voronoi vertex and edge can be reconstructed using the intersection between the finite edge with the
// input polygon.
// Rotation of the polygons solves this problem.
TEST_CASE("Voronoi missing vertex 2", "[VoronoiMissingVertex2]")
{
Polygons poly = {
Polygon {
{ 50000000, 50000000},
{-50000000, 50000000},
{-50000000, -50000000},
{ 50000000, -50000000},
},
Polygon {
{-45000000, -45000000},
{-45000000, 45000000},
{ 45000000, 45000000},
{ 45000000, 8280000},
{ 45000000, -45000000},
}
};
// polygons_rotate(poly, PI / 6);
double area = std::accumulate(poly.begin(), poly.end(), 0., [](double a, auto &poly) { return a + poly.area(); });
REQUIRE(area > 0.);
REQUIRE(intersecting_edges(poly).empty());
VD vd;
Lines lines = to_lines(poly);
construct_voronoi(lines.begin(), lines.end(), &vd);
#ifdef VORONOI_DEBUG_OUT
dump_voronoi_to_svg(debug_out_path("voronoi-missing-vertex2-out.svg").c_str(), vd, Points(), lines);
#endif
// REQUIRE(!has_missing_voronoi_vertices(poly, vd));
}
// This case is composed of two polygons, and again one of the edges is divided into two parts by a point that lies on this edge,
// and for this point is Voronoi vertex missing. A difference between the previous cases and this case through the missing
// Voronoi vertex is passing finite edge between one inner Voronoi vertex and one outer Voronoi vertex.
// Rotating the polygon also help solve this problem.
TEST_CASE("Voronoi missing vertex 3", "[VoronoiMissingVertex3]")
{
Polygons poly = {
Polygon {
{-29715088, -29310899},
{-29022573, -28618384},
{-27771147, -27366958},
{-28539221, -26519393},
{-30619013, -28586348},
{-29812018, -29407830},
},
Polygon {
{-27035112, -28071875},
{-27367482, -27770679},
{-28387008, -28790205},
{-29309438, -29712635},
{-29406319, -29809515},
{-29032985, -30179156},
}
};
double area = std::accumulate(poly.begin(), poly.end(), 0., [](double a, auto &poly){ return a + poly.area(); });
REQUIRE(area > 0.);
REQUIRE(intersecting_edges(poly).empty());
// polygons_rotate(poly, PI/180);
// polygons_rotate(poly, PI/6);
VD vd;
Lines lines = to_lines(poly);
construct_voronoi(lines.begin(), lines.end(), &vd);
#ifdef VORONOI_DEBUG_OUT
dump_voronoi_to_svg(debug_out_path("voronoi-missing-vertex3-out.svg").c_str(), vd, Points(), lines);
#endif
// REQUIRE(!has_missing_voronoi_vertices(poly, vd));
}
// In this case, the Voronoi vertex (146873, -146873) is included twice.
// Also, near to those duplicate Voronoi vertices is another Voronoi vertex (146872, -146872).
// Rotating the polygon will help solve this problem, but then there arise three very close Voronoi vertices.
// Rotating of the input polygon will help solve this problem.
TEST_CASE("Duplicate Voronoi vertices", "[Voronoi]")
{
Polygon poly = {
{ 25000000, 25000000},
{-25000000, 25000000},
{-25000000, -25000000},
{ 146872, -25000000},
{ 9912498, -25000000},
{ 25000000, -25000000},
{ 25000000, - 8056252},
{ 25000000, - 146873},
{ 25000000, 10790627},
};
// poly.rotate(PI / 6);
REQUIRE(poly.area() > 0.);
REQUIRE(intersecting_edges({poly}).empty());
VD vd;
Lines lines = to_lines(poly);
construct_voronoi(lines.begin(), lines.end(), &vd);
#ifdef VORONOI_DEBUG_OUT
dump_voronoi_to_svg(debug_out_path("voronoi-duplicate-vertices-out.svg").c_str(), vd, Points(), lines);
#endif
[[maybe_unused]] auto has_duplicate_vertices = [](const VD &vd) -> bool {
std::vector<Vec2d> vertices;
for (const auto &vertex : vd.vertices())
vertices.emplace_back(Vec2d(vertex.x(), vertex.y()));
std::sort(vertices.begin(), vertices.end(), [](const Vec2d &l, const Vec2d &r) { return l.x() < r.x() || (l.x() == r.x() && l.y() < r.y()); });
return std::unique(vertices.begin(), vertices.end()) != vertices.end();
};
// REQUIRE(!has_duplicate_vertices(vd));
}
// In this case, there are three very close Voronoi vertices like in the previous test case after rotation. There is also one
// missing Voronoi vertex. One infinity-edge (after clip [(146872, -70146871), (146872, -146871)]) passes through this missing
// Voronoi vertex. This infinite edge [(146872, -70146871), (146872, -146871)] and edge [(146873, -146873), (0, 0)] are intersecting.
// They intersect probably because the three points are very close to each other, with a combination of the missing Voronoi vertex.
// Rotating of the input polygon will help solve this problem.
TEST_CASE("Intersecting Voronoi edges", "[Voronoi]")
{
Polygon poly = {
{ 25000000, 25000000},
{-25000000, 25000000},
{-25000000, -25000000},
{ 146872, -25000000},
{ 25000000, -25000000},
{ 25000000, - 146873},
};
// poly.rotate(PI / 6);
REQUIRE(poly.area() > 0.);
REQUIRE(intersecting_edges({poly}).empty());
VD vd;
Lines lines = to_lines(poly);
construct_voronoi(lines.begin(), lines.end(), &vd);
#ifdef VORONOI_DEBUG_OUT
dump_voronoi_to_svg(debug_out_path("voronoi-intersecting-edges-out.svg").c_str(), vd, Points(), lines);
#endif
[[maybe_unused]] auto has_intersecting_edges = [](const Polygon &poly, const VD &vd) -> bool {
BoundingBox bbox = get_extents(poly);
const double bbox_dim_max = double(std::max(bbox.size().x(), bbox.size().y()));
std::vector<Voronoi::Internal::segment_type> segments;
for (const Line &line : to_lines(poly))
segments.emplace_back(Voronoi::Internal::point_type(double(line.a.x()), double(line.a.y())),
Voronoi::Internal::point_type(double(line.b.x()), double(line.b.y())));
Lines edges;
for (const auto &edge : vd.edges())
if (edge.cell()->source_index() < edge.twin()->cell()->source_index()) {
if (edge.is_finite()) {
edges.emplace_back(Point(coord_t(edge.vertex0()->x()), coord_t(edge.vertex0()->y())),
Point(coord_t(edge.vertex1()->x()), coord_t(edge.vertex1()->y())));
} else if (edge.is_infinite()) {
std::vector<Voronoi::Internal::point_type> samples;
Voronoi::Internal::clip_infinite_edge(poly.points, segments, edge, bbox_dim_max, &samples);
if (!samples.empty())
edges.emplace_back(Point(coord_t(samples[0].x()), coord_t(samples[0].y())), Point(coord_t(samples[1].x()), coord_t(samples[1].y())));
}
}
Point intersect_point;
for (auto first_it = edges.begin(); first_it != edges.end(); ++first_it)
for (auto second_it = first_it + 1; second_it != edges.end(); ++second_it)
if (first_it->intersection(*second_it, &intersect_point) && first_it->a != intersect_point && first_it->b != intersect_point)
return true;
return false;
};
// REQUIRE(!has_intersecting_edges(poly, vd));
}