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Fix self-intersecting output in clean_extreme_slopes_outer/inner #37

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Merged
fontanf merged 1 commit into from
Jun 30, 2026
Merged

Fix self-intersecting output in clean_extreme_slopes_outer/inner #37

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43 changes: 43 additions & 0 deletions data/tests/clean/clean_extreme_slopes_inner/0.json
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,43 @@
{
"shape": {
"elements": [
{
"end": {
"x": 29.641303008447174,
"y": 48.08931284909132
},
"start": {
"x": 29.773738644876477,
"y": 12.823728609920455
},
"type": "LineSegment"
},
{
"end": {
"x": 29.640719144732877,
"y": 48.089310656461755
},
"start": {
"x": 29.641303008447174,
"y": 48.08931284909132
},
"type": "LineSegment"
},
{
"end": {
"x": 29.773738644876477,
"y": 12.823728609920455
},
"start": {
"x": 29.640719144732877,
"y": 48.089310656461755
},
"type": "LineSegment"
}
],
"is_path": false,
"type": "general"
},
"expected_output": [
]
}
94 changes: 80 additions & 14 deletions src/clean.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,8 +5,10 @@
#include "shape/elements_intersections.hpp"
#include "shape/equalize.hpp"
#include "shape/boolean_operations.hpp"
#include "shape/shapes_intersections.hpp"
#ifdef CLEAN_ENABLE_DEBUG
#include "shape/writer.hpp"
#include <fstream>
#endif

//#include <iostream>
Expand Down Expand Up @@ -282,7 +284,8 @@ namespace
{

Shape clean_extreme_slopes_outer_1(
Shape shape_orig)
Shape shape_orig,
std::vector<Shape>& triangles_added)
{
Shape shape = shape_orig;

Expand Down Expand Up @@ -344,9 +347,8 @@ Shape clean_extreme_slopes_outer_1(
shape_new.elements.push_back(element_cur);
start = element_cur.end;
} else {
//std::cout << "remove" << std::endl;
//std::cout << "element_cur: " << element_cur.to_string() << std::endl;
//std::cout << "element_next: " << element_next.to_string() << std::endl;
triangles_added.push_back(build_triangle(
start, element_cur.end, element_next.end));
}
}
shape_new.elements[0].start = start;
Expand Down Expand Up @@ -414,9 +416,8 @@ Shape clean_extreme_slopes_outer_1(
shape_new.elements.push_back(element_cur);
end = element_cur.start;
} else {
//std::cout << "remove" << std::endl;
//std::cout << "element_cur: " << element_cur.to_string() << std::endl;
//std::cout << "element_prev: " << element_prev.to_string() << std::endl;
triangles_added.push_back(build_triangle(
element_prev.start, element_cur.start, end));
}
}
shape_new.elements[0].end = end;
Expand All @@ -428,7 +429,8 @@ Shape clean_extreme_slopes_outer_1(
}

Shape clean_extreme_slopes_inner_1(
const Shape& shape_orig)
const Shape& shape_orig,
std::vector<Shape>& triangles_removed)
{
Shape shape = shape_orig;

Expand Down Expand Up @@ -489,6 +491,9 @@ Shape clean_extreme_slopes_inner_1(
if (!remove) {
shape_new.elements.push_back(element_cur);
start = element_cur.end;
} else {
triangles_removed.push_back(build_triangle(
start, element_cur.end, element_next.end));
}
}
shape_new.elements[0].start = start;
Expand Down Expand Up @@ -552,6 +557,9 @@ Shape clean_extreme_slopes_inner_1(
if (!remove) {
shape_new.elements.push_back(element_cur);
end = element_cur.start;
} else {
triangles_removed.push_back(build_triangle(
element_prev.start, element_cur.start, end));
}
}
shape_new.elements[0].end = end;
Expand All @@ -563,7 +571,8 @@ Shape clean_extreme_slopes_inner_1(
}

Shape clean_extreme_slopes_outer_2(
const Shape& shape_orig)
const Shape& shape_orig,
std::vector<Shape>& triangles_added)
{
if (!shape_orig.check()) {
throw std::invalid_argument(
Expand Down Expand Up @@ -594,6 +603,8 @@ Shape clean_extreme_slopes_outer_2(
element_prev.start, element_prev.end,
{element_cur.end.x, element_cur.start.y}, element_cur.end);
if (p.first) {
triangles_added.push_back(build_triangle(
element_prev.start, element_cur.start, element_cur.end));
element_prev.end = p.second;
element_cur.start = p.second;
}
Expand All @@ -608,6 +619,8 @@ Shape clean_extreme_slopes_outer_2(
element_prev.start, element_prev.end,
{element_cur.start.x, element_cur.end.y}, element_cur.end);
if (p.first) {
triangles_added.push_back(build_triangle(
element_prev.start, element_cur.start, element_cur.end));
element_prev.end = p.second;
element_cur.start = p.second;
}
Expand Down Expand Up @@ -637,6 +650,8 @@ Shape clean_extreme_slopes_outer_2(
element_cur.start, {element_cur.start.x, element_cur.end.y},
element_next.start, element_next.end);
if (p.first) {
triangles_added.push_back(build_triangle(
element_cur.start, element_cur.end, element_next.end));
element_cur.end = p.second;
element_next.start = p.second;
}
Expand All @@ -651,6 +666,8 @@ Shape clean_extreme_slopes_outer_2(
element_cur.start, {element_cur.end.x, element_cur.start.y},
element_next.start, element_next.end);
if (p.first) {
triangles_added.push_back(build_triangle(
element_cur.start, element_cur.end, element_next.end));
element_cur.end = p.second;
element_next.start = p.second;
}
Expand All @@ -664,7 +681,8 @@ Shape clean_extreme_slopes_outer_2(
}

Shape clean_extreme_slopes_inner_2(
const Shape& shape_orig)
const Shape& shape_orig,
std::vector<Shape>& triangles_removed)
{
Shape shape = shape_orig;
ElementPos element_prev_pos = shape.elements.size() - 1;
Expand All @@ -691,6 +709,8 @@ Shape clean_extreme_slopes_inner_2(
element_prev.start, element_prev.end,
{element_cur.end.x, element_cur.start.y}, element_cur.end);
if (p.first) {
triangles_removed.push_back(build_triangle(
element_prev.start, element_cur.start, element_cur.end));
element_prev.end = p.second;
element_cur.start = p.second;
}
Expand All @@ -705,6 +725,8 @@ Shape clean_extreme_slopes_inner_2(
element_prev.start, element_prev.end,
{element_cur.start.x, element_cur.end.y}, element_cur.end);
if (p.first) {
triangles_removed.push_back(build_triangle(
element_prev.start, element_cur.start, element_cur.end));
element_prev.end = p.second;
element_cur.start = p.second;
}
Expand Down Expand Up @@ -737,6 +759,8 @@ Shape clean_extreme_slopes_inner_2(
element_cur.start, {element_cur.start.x, element_cur.end.y},
element_next.start, element_next.end);
if (p.first) {
triangles_removed.push_back(build_triangle(
element_cur.start, element_cur.end, element_next.end));
element_cur.end = p.second;
element_next.start = p.second;
}
Expand All @@ -751,6 +775,8 @@ Shape clean_extreme_slopes_inner_2(
element_cur.start, {element_cur.end.x, element_cur.start.y},
element_next.start, element_next.end);
if (p.first) {
triangles_removed.push_back(build_triangle(
element_cur.start, element_cur.end, element_next.end));
element_cur.end = p.second;
element_next.start = p.second;
}
Expand All @@ -775,23 +801,38 @@ ShapeWithHoles shape::clean_extreme_slopes_outer(
}

Shape shape = shape_orig;
std::vector<Shape> triangles_added;

shape = equalize_shape(shape);
shape = remove_redundant_vertices(shape).second;
shape = remove_aligned_vertices(shape).second;

shape = clean_extreme_slopes_outer_1(shape);
shape = clean_extreme_slopes_outer_1(shape, triangles_added);

shape = equalize_shape(shape);
shape = remove_redundant_vertices(shape).second;
shape = remove_aligned_vertices(shape).second;

shape = clean_extreme_slopes_outer_2(shape);
shape = clean_extreme_slopes_outer_2(shape, triangles_added);

shape = equalize_shape(shape);
shape = remove_redundant_vertices(shape).second;
shape = remove_aligned_vertices(shape).second;

if (!triangles_added.empty() && intersect(shape)) {
// The naive in-place mutations performed by clean_extreme_slopes_outer_1
// and clean_extreme_slopes_outer_2 can produce a self-intersecting
// shape. When that happens, fall back to a robust reconstruction:
// union the corner triangles identified by those two passes with the
// original shape, the same approach used by simplify() to recover
// from invalid in-place simplifications.
std::vector<ShapeWithHoles> shapes_to_union = {{shape_orig}};
for (const Shape& triangle: triangles_added)
shapes_to_union.push_back({triangle});
std::vector<ShapeWithHoles> u = compute_union(shapes_to_union);
return u.front();
}

if (!shape.check()) {
throw std::invalid_argument(
FUNC_SIGNATURE + ": "
Expand All @@ -810,26 +851,51 @@ std::vector<Shape> shape::clean_extreme_slopes_inner(
}

Shape shape = shape_orig;
std::vector<Shape> triangles_removed;

shape = equalize_shape(shape);
shape = remove_redundant_vertices(shape).second;
shape = remove_aligned_vertices(shape).second;

shape = clean_extreme_slopes_inner_1(shape);
shape = clean_extreme_slopes_inner_1(shape, triangles_removed);

shape = equalize_shape(shape);
shape = remove_redundant_vertices(shape).second;
shape = remove_aligned_vertices(shape).second;

shape = clean_extreme_slopes_inner_2(shape);
shape = clean_extreme_slopes_inner_2(shape, triangles_removed);

shape = equalize_shape(shape);
shape = remove_redundant_vertices(shape).second;
shape = remove_aligned_vertices(shape).second;

if (!triangles_removed.empty() && intersect(shape)) {
// The naive in-place mutations performed by clean_extreme_slopes_inner_1
// and clean_extreme_slopes_inner_2 can produce a self-intersecting
// shape. When that happens, fall back to a robust reconstruction: cut
// the corner triangles identified by those two passes directly out of
// the original shape using a boolean difference, the same approach
// used by simplify() to recover from invalid in-place simplifications.
std::vector<ShapeWithHoles> triangles_removed_swh;
for (const Shape& triangle: triangles_removed)
triangles_removed_swh.push_back({triangle});
std::vector<ShapeWithHoles> difference = compute_difference(
{{shape_orig}},
triangles_removed_swh);

std::vector<Shape> output;
for (const ShapeWithHoles& shape_with_holes: difference)
output.push_back(shape_with_holes.shape);
return output;
}

if (!shape.check()) {
#ifdef CLEAN_ENABLE_DEBUG
Writer().add_shape(shape_orig).add_shape(shape).write_json("tmp.json");
std::ofstream file{"clean_extreme_slopes_inner_inputs.json"};
nlohmann::json json;
json["shape"] = shape_orig.to_json();
file << std::setw(4) << json << std::endl;
#endif
throw std::invalid_argument(
FUNC_SIGNATURE + ": "
Expand Down
79 changes: 79 additions & 0 deletions test/clean_test.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,85 @@ INSTANTIATE_TEST_SUITE_P(
});


struct CleanExtremeSlopesInnerTestParams
{
std::string name;
Shape shape;
std::vector<Shape> expected_output;


static CleanExtremeSlopesInnerTestParams read_json(
const std::string& file_path)
{
std::ifstream file(file_path);
if (!file.good()) {
throw std::runtime_error(
FUNC_SIGNATURE + ": "
"unable to open file \"" + file_path + "\".");
}

nlohmann::json json;
file >> json;
CleanExtremeSlopesInnerTestParams test_params;
test_params.name = file_path;
test_params.shape = Shape::from_json(json["shape"]);
for (auto& json_shape: json["expected_output"].items())
test_params.expected_output.emplace_back(Shape::from_json(json_shape.value()));
return test_params;
}
};

void PrintTo(const CleanExtremeSlopesInnerTestParams& params, std::ostream* os)
{
*os << "shape " << params.shape.to_string(2) << "\n";
*os << "expected_output\n";
for (const Shape& shape: params.expected_output)
*os << shape.to_string(2) << "\n";
}

class CleanExtremeSlopesInnerTest: public testing::TestWithParam<CleanExtremeSlopesInnerTestParams> { };

TEST_P(CleanExtremeSlopesInnerTest, CleanExtremeSlopesInner)
{
CleanExtremeSlopesInnerTestParams test_params = GetParam();
PrintTo(test_params, &std::cout);

std::vector<Shape> output = clean_extreme_slopes_inner(test_params.shape);
std::cout << "output" << std::endl;
for (const Shape& shape: output)
std::cout << shape.to_string(2) << std::endl;

ASSERT_EQ(output.size(), test_params.expected_output.size());
for (const Shape& expected_shape: test_params.expected_output) {
EXPECT_NE(std::find_if(
output.begin(),
output.end(),
[&expected_shape](const Shape& shape) { return equal(shape, expected_shape); }),
output.end());
}
}

INSTANTIATE_TEST_SUITE_P(
Shape,
CleanExtremeSlopesInnerTest,
testing::ValuesIn(std::vector<CleanExtremeSlopesInnerTestParams>{
{
"Square",
build_shape({{0, 0}, {1, 0}, {1, 1}, {0, 1}}),
{build_shape({{0, 0}, {1, 0}, {1, 1}, {0, 1}})},
}, {
"NearVerticalSpike",
build_shape({{0, 0}, {10, -10}, {10.1, -110}, {20, 0}}),
{build_shape({{0, 0}, {10.1, -110}, {20, 0}})},
},
CleanExtremeSlopesInnerTestParams::read_json(
(fs::path("data") / "tests" / "clean" / "clean_extreme_slopes_inner" / "0.json").string()),
}),
[](const testing::TestParamInfo<CleanExtremeSlopesInnerTest::ParamType>& info) {
return fs::path(info.param.name).stem().string();
});


struct FixSelfIntersectionsTestParams
{
std::string name;
Expand Down
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