From 1b3689034f20545ea77e171218a0726bbb9f1ce7 Mon Sep 17 00:00:00 2001
From: jatoben <ben@dangerdevices.com>
Date: Sat, 23 Nov 2024 03:53:15 -0800
Subject: [PATCH] Do not discard minimum-length paths in
 `FlexPath::remove_overlapping_points()` (#278)

* Test minimum-length paths

* Only discard point if length is strictly less than tolerance
---
 src/flexpath.cpp          |   2 +-
 tests/flexpath_test.py    |   9 +++++++++
 tests/library_test.py     |  33 +++++++++++++++++++++++++++++++--
 tests/min_length_path.oas | Bin 0 -> 518 bytes
 4 files changed, 41 insertions(+), 3 deletions(-)
 create mode 100644 tests/min_length_path.oas

diff --git a/src/flexpath.cpp b/src/flexpath.cpp
index 9d79ef518..4693eb619 100644
--- a/src/flexpath.cpp
+++ b/src/flexpath.cpp
@@ -226,7 +226,7 @@ void FlexPath::remove_overlapping_points() {
     const double tol_sq = spine.tolerance * spine.tolerance;
     Array<Vec2>* array = &spine.point_array;
     for (uint64_t i = 1; i < array->count;) {
-        if (((*array)[i] - (*array)[i - 1]).length_sq() <= tol_sq) {
+        if (((*array)[i] - (*array)[i - 1]).length_sq() < tol_sq) {
             array->remove(i);
             FlexPathElement* el = elements;
             for (uint64_t ne = 0; ne < num_elements; ne++, el++)
diff --git a/tests/flexpath_test.py b/tests/flexpath_test.py
index f598d5ab6..08686f354 100644
--- a/tests/flexpath_test.py
+++ b/tests/flexpath_test.py
@@ -166,3 +166,12 @@ def test_raith_data():
     assert path.raith_data.periods == 5
     assert path.raith_data.grating_type == 6
     assert path.raith_data.dots_per_cycle == 7
+
+
+def test_min_length():
+    lib = gdstk.Library("test")
+    tol = lib.precision / lib.unit
+
+    path = gdstk.FlexPath(((0, 0), (tol, 0)), width=0.01, tolerance=tol)
+    assert path.to_polygons()
+
diff --git a/tests/library_test.py b/tests/library_test.py
index 2a2ced86f..2f9ba8639 100644
--- a/tests/library_test.py
+++ b/tests/library_test.py
@@ -5,11 +5,14 @@
 # Boost Software License - Version 1.0.  See the accompanying
 # LICENSE file or <http://www.boost.org/LICENSE_1_0.txt>
 
-from datetime import datetime
 import hashlib
 import pathlib
-import pytest
+from datetime import datetime
+from typing import Callable, Union
+
 import numpy
+import pytest
+
 import gdstk
 
 
@@ -532,3 +535,29 @@ def test_roundtrip_path_ends(tmpdir: pathlib.Path):
         assert (
             path.ends == gds_path.ends and path.ends == oas_path.ends
         ), f"expected: {path.ends}, gds: {gds_path.ends}, oas: {oas_path.ends}"
+
+
+@pytest.mark.parametrize(
+    "write_f, read_f",
+    (
+        (gdstk.Library.write_oas, gdstk.read_oas),
+        (gdstk.Library.write_gds, gdstk.read_gds),
+    ),
+)
+def test_write_min_length_path(
+    write_f: Callable[[gdstk.Library, Union[str, pathlib.Path]], None],
+    read_f: Callable[Union[str, pathlib.Path], gdstk.Library],
+    tmp_path: pathlib.Path
+):
+    source = gdstk.read_oas(pathlib.Path(__file__).parent / "min_length_path.oas")
+    assert source.cells[0].paths
+
+    rw_path = tmp_path / "out"
+    write_f(source, rw_path)
+    rw = read_f(rw_path)
+    assert rw.cells[0].paths
+
+    assert numpy.array_equal(
+        source.cells[0].paths[0].spine(),
+        rw.cells[0].paths[0].spine(),
+    )
diff --git a/tests/min_length_path.oas b/tests/min_length_path.oas
new file mode 100644
index 0000000000000000000000000000000000000000..4be94d3b4a071d8b5fa598435293d20b28e03598
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