Add spoly_is_convex

Author: ggnmstr

Diff for: 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 for: expected/init_test.out.in

@@ -33,3 +33,4 @@ psql:pg_sphere.test.sql:8622: NOTICE:  argument type pointkey is only a shell
 psql:pg_sphere.test.sql:8628: NOTICE:  argument type pointkey is only a shell
 psql:pg_sphere.test.sql:8634: NOTICE:  argument type pointkey is only a shell
 psql:pg_sphere.test.sql:8640: NOTICE:  argument type pointkey is only a shell
+

Diff for: expected/init_test_healpix.out.in

@@ -1,2 +1,3 @@
 psql:pg_sphere.test.sql:9207: NOTICE:  return type smoc is only a shell
 psql:pg_sphere.test.sql:9213: NOTICE:  argument type smoc is only a shell
+

Diff for: 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 for: 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 for: 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 for: 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 for: 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 for: upgrade_scripts/pg_sphere--1.2.3--1.3.0.sql.in

@@ -54,3 +54,12 @@ CREATE FUNCTION spoly_as_array(spoly)
 
 COMMENT ON FUNCTION  spoly_as_array(spoly) IS
   'returns spoly as array of points';
+
+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';