postgrespro · vitcpp · Aug 12, 2023 · Jul 27, 2023
diff --git a/doc/functions.sgm b/doc/functions.sgm
@@ -618,6 +618,33 @@
               </programlisting>
             </example>
             </sect3>
+
+          <sect3 id="funcs.spoly.isconvex">
+            <title>
+              Spoly is convex
+            </title>
+            <para>
+              Returns true if the specified spherical polygon is convex.
+              Returns false otherwise.
+            </para>
+            <funcsynopsis>
+              <funcprototype>
+                <funcdef><function>spoly_is_convex</function></funcdef>
+                  <paramdef>spoly <parameter>polygon</parameter></paramdef>
+              </funcprototype>
+            </funcsynopsis>
+            <example>
+              <title>Check if polygon is convex</title>
+              <programlisting>
+<![CDATA[sql> SELECT spoly_is_convex( spoly '{(0,0),(1,0),(1,1),(1,2)}' );]]>
+<![CDATA[ spoly_is_convex]]>
+<![CDATA[-----------------]]>
+<![CDATA[ t]]>
+<![CDATA[ (1 row)]]>
+              </programlisting>
+            </example>
+          </sect3>
+
         </sect2>
 
         <sect2 id="funcs.sbox">

diff --git a/expected/init_test.out.in b/expected/init_test.out.in
@@ -24,12 +24,12 @@ psql:pg_sphere.test.sql:158: NOTICE:  argument type spath is only a shell
 psql:pg_sphere.test.sql:177: NOTICE:  type "sbox" is not yet defined
 DETAIL:  Creating a shell type definition.
 psql:pg_sphere.test.sql:184: NOTICE:  argument type sbox is only a shell
-psql:pg_sphere.test.sql:8644: NOTICE:  type "spherekey" is not yet defined
+psql:pg_sphere.test.sql:8658: NOTICE:  type "spherekey" is not yet defined
 DETAIL:  Creating a shell type definition.
-psql:pg_sphere.test.sql:8651: NOTICE:  argument type spherekey is only a shell
-psql:pg_sphere.test.sql:8665: NOTICE:  type "pointkey" is not yet defined
+psql:pg_sphere.test.sql:8665: NOTICE:  argument type spherekey is only a shell
+psql:pg_sphere.test.sql:8679: NOTICE:  type "pointkey" is not yet defined
 DETAIL:  Creating a shell type definition.
-psql:pg_sphere.test.sql:8672: NOTICE:  argument type pointkey is only a shell
-psql:pg_sphere.test.sql:8678: NOTICE:  argument type pointkey is only a shell
-psql:pg_sphere.test.sql:8684: NOTICE:  argument type pointkey is only a shell
-psql:pg_sphere.test.sql:8690: NOTICE:  argument type pointkey is only a shell
+psql:pg_sphere.test.sql:8686: NOTICE:  argument type pointkey is only a shell
+psql:pg_sphere.test.sql:8692: NOTICE:  argument type pointkey is only a shell
+psql:pg_sphere.test.sql:8698: NOTICE:  argument type pointkey is only a shell
+psql:pg_sphere.test.sql:8704: NOTICE:  argument type pointkey is only a shell
diff --git a/expected/init_test_healpix.out.in b/expected/init_test_healpix.out.in
@@ -1,2 +1,2 @@
-psql:pg_sphere.test.sql:9257: NOTICE:  return type smoc is only a shell
-psql:pg_sphere.test.sql:9263: NOTICE:  argument type smoc is only a shell
+psql:pg_sphere.test.sql:9271: NOTICE:  return type smoc is only a shell
+psql:pg_sphere.test.sql:9277: NOTICE:  argument type smoc is only a shell
diff --git a/expected/poly.out b/expected/poly.out
@@ -1799,3 +1799,28 @@ SELECT  spoly_as_array( spoly '{(0,0),(1,0),(1,1)}' );
  {"(0 , 0)","(1 , 0)","(1 , 1)"}
 (1 row)
 
+-- spoly is convex
+SELECT spoly_is_convex(spoly'{(53d 45m 35.0s, 37d 6m 30.0s), (52d 21m 36.0s, 41d 36m 7.0s), (54d 14m 18.0s, 45d 1m 35.0s), (51d 23m 3.0s, 45d 22m 49.0s), (51d 2m 12.0s, 41d 52m 1.0s), (50d 41m 47.0s, 38d 22m 0s) }');
+ spoly_is_convex 
+-----------------
+ f
+(1 row)
+
+SELECT spoly_is_convex(spoly'{(12d,32d),(34d,12d),(59d,21d),(69d,21d)}');
+ spoly_is_convex 
+-----------------
+ f
+(1 row)
+
+SELECT spoly_is_convex(spoly'{(12d,32d),(34d,12d),(59d,21d),(34d,40d)}');
+ spoly_is_convex 
+-----------------
+ t
+(1 row)
+
+SELECT spoly_is_convex(NULL);
+ spoly_is_convex 
+-----------------
+ f
+(1 row)
+
diff --git a/pgs_polygon.sql.in b/pgs_polygon.sql.in
@@ -973,3 +973,17 @@ CREATE AGGREGATE spoly (
     stype     = spoly,
     finalfunc = spoly_add_points_fin_aggr
 );
+
+
+--
+-- polygon is convex
+--
+
+CREATE FUNCTION spoly_is_convex(spoly)
+   RETURNS BOOL
+   AS 'MODULE_PATHNAME', 'spherepoly_is_convex'
+   LANGUAGE 'c'
+   IMMUTABLE PARALLEL SAFE;
+
+COMMENT ON FUNCTION spoly_is_convex(spoly) IS
+  'true if spherical polygon is convex';
diff --git a/sql/poly.sql b/sql/poly.sql
@@ -616,3 +616,9 @@ SELECT  spoint( spoly '{(0,0),(1,0),(1,1)}', 1 );
 SELECT  spoint( spoly '{(0,0),(1,0),(1,1)}', 2 );
 SELECT  spoint( spoly '{(0,0),(1,0),(1,1)}', 3 );
 SELECT  spoly_as_array( spoly '{(0,0),(1,0),(1,1)}' );
+
+-- spoly is convex
+SELECT spoly_is_convex(spoly'{(53d 45m 35.0s, 37d 6m 30.0s), (52d 21m 36.0s, 41d 36m 7.0s), (54d 14m 18.0s, 45d 1m 35.0s), (51d 23m 3.0s, 45d 22m 49.0s), (51d 2m 12.0s, 41d 52m 1.0s), (50d 41m 47.0s, 38d 22m 0s) }');
+SELECT spoly_is_convex(spoly'{(12d,32d),(34d,12d),(59d,21d),(69d,21d)}');
+SELECT spoly_is_convex(spoly'{(12d,32d),(34d,12d),(59d,21d),(34d,40d)}');
+SELECT spoly_is_convex(NULL);
diff --git a/src/polygon.c b/src/polygon.c
@@ -59,6 +59,7 @@ PG_FUNCTION_INFO_V1(spheretrans_poly);
 PG_FUNCTION_INFO_V1(spheretrans_poly_inverse);
 PG_FUNCTION_INFO_V1(spherepoly_add_point);
 PG_FUNCTION_INFO_V1(spherepoly_add_points_finalize);
+PG_FUNCTION_INFO_V1(spherepoly_is_convex);
 
 
  /*
@@ -1531,3 +1532,54 @@ spherepoly_add_points_finalize(PG_FUNCTION_ARGS)
 	}
 	PG_RETURN_POINTER(poly);
 }
+
+
+Datum
+spherepoly_is_convex(PG_FUNCTION_ARGS)
+{
+	Vector3D	u,
+				v,
+				vsu,
+				wsv,
+				crs;
+	int32 		i;
+	float8		cur = 0.0,
+				prev = 0.0;
+	SPOLY		*poly = (SPOLY *) PG_GETARG_POINTER(0);
+
+	if (poly == NULL)
+	{
+		PG_RETURN_BOOL(false);
+	}
+
+	poly = PG_GETARG_SPOLY(0);
+	if (poly->npts == 3)
+	{
+		PG_RETURN_BOOL(true);
+	}
+
+	for (i = 0; i < poly->npts; i++)
+	{
+		const int j = (i - 1 + poly->npts) % poly->npts;
+		const int k = (i + 1) % poly->npts;
+
+		spoint_vector3d(&u, &poly->p[i]);
+		spoint_vector3d(&v, &poly->p[j]);
+		spoint_vector3d(&vsu, &poly->p[j]);
+		spoint_vector3d(&wsv, &poly->p[k]);
+
+		vector3d_addwithscalar(&vsu, -1, &u);
+		vector3d_addwithscalar(&wsv, -1, &v);
+
+		vector3d_cross(&crs, &vsu, &wsv);
+
+		cur = vector3d_scalar(&crs, &v);
+		if (cur * prev < 0)
+		{
+			PG_RETURN_BOOL(false);
+		}
+		prev = cur;
+	}
+
+	PG_RETURN_BOOL(true);
+}
diff --git a/src/polygon.h b/src/polygon.h
@@ -358,4 +358,9 @@ Datum	spherepoly_add_points_finalize(PG_FUNCTION_ARGS);
  */
 Datum	spherepoly_get_array(PG_FUNCTION_ARGS);
 
+/*
+ * Checks whether a polygon is convex
+ */
+Datum	spherepoly_is_convex(PG_FUNCTION_ARGS);
+
 #endif
diff --git a/upgrade_scripts/pg_sphere--1.2.3--1.3.0.sql.in b/upgrade_scripts/pg_sphere--1.2.3--1.3.0.sql.in
@@ -93,3 +93,12 @@ CREATE OPERATOR  <-> (
 
 COMMENT ON OPERATOR <-> (spoint, sline) IS
   'returns the distance between spherical line and spherical point';
+
+CREATE FUNCTION spoly_is_convex(spoly)
+   RETURNS BOOL
+   AS 'MODULE_PATHNAME', 'spherepoly_is_convex'
+   LANGUAGE 'c'
+   IMMUTABLE PARALLEL SAFE;
+
+COMMENT ON FUNCTION spoly_is_convex(spoly) IS
+  'true if spherical polygon is convex';