Do not remove points when doubling back at zero tolerance, references…

… #5654
postgis · Apr 17, 2024 · 2c68d13 · 2c68d13
1 parent eb50b64
commit 2c68d13
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Showing 2 changed files with 20 additions and 1 deletion.
diff --git a/liblwgeom/cunit/cu_algorithm.c b/liblwgeom/cunit/cu_algorithm.c
@@ -1813,13 +1813,28 @@ static void test_trim_bits(void)
 	lwline_free(line);
 }
 
+static void test_ptarray_simplify(void)
+{
+	LWGEOM *geom1 = lwgeom_from_wkt("LINESTRING (2 2,3 2,4 1,3 2, 4 4)", LW_PARSER_CHECK_NONE);
+	LWGEOM *geom2 = lwgeom_from_wkt("LINESTRING (2 2,3 2,4 1,3 2, 4 4)", LW_PARSER_CHECK_NONE);
+	LWLINE *line1 = (LWLINE*)geom1;
+	double tolerance = 0.0;
+	int minpts = 2;
+	ptarray_simplify_in_place(line1->points, tolerance, minpts);
+	ASSERT_LWGEOM_EQUAL(geom1, geom2);
+	lwgeom_free(geom1);
+	lwgeom_free(geom2);
+}
+
+
 /*
 ** Used by test harness to register the tests in this file.
 */
 void algorithms_suite_setup(void);
 void algorithms_suite_setup(void)
 {
 	CU_pSuite suite = CU_add_suite("algorithm", init_cg_suite, clean_cg_suite);
+	PG_ADD_TEST(suite,test_ptarray_simplify);
 	PG_ADD_TEST(suite,test_lw_segment_side);
 	PG_ADD_TEST(suite,test_lw_segment_intersects);
 	PG_ADD_TEST(suite,test_lwline_crossing_short_lines);

diff --git a/liblwgeom/ptarray.c b/liblwgeom/ptarray.c
@@ -1689,7 +1689,11 @@ ptarray_simplify_in_place_tolerance0(POINTARRAY *pa)
 		double dot_ac_ab = ca_x * ba_x + ca_y * ba_y;
 		double s_numerator = ca_x * ba_y - ca_y * ba_x;
 
-		if (dot_ac_ab < 0.0 || dot_ac_ab > ab_length_sqr || s_numerator != 0)
+		if (p2d_same(kept_pt, next_pt) ||
+			dot_ac_ab < 0.0 ||
+			dot_ac_ab > ab_length_sqr ||
+			s_numerator != 0)
+
 		{
 			kept_it++;
 			kept_pt = curr_pt;