Vlib: sync Vect_point_in_*() fns, add comments

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@64206 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/vector/Vlib/poly.c

@@ -558,8 +558,12 @@ static int segments_x_ray(double X, double Y, const struct line_pnts *Points)
 	x2 = Points->x[n];
 	y2 = Points->y[n];
 
+	/* G_debug() is slow, avoid it in loops over points,
+	 * activate when needed */
+	/*
 	G_debug(3, "X = %f Y = %f x1 = %f y1 = %f x2 = %f y2 = %f", X, Y, x1,
 		y1, x2, y2);
+	 */
 
 	/* I know, it should be possible to do that with less conditions,
 	 * but it should be enough readable also! */
@@ -653,7 +657,7 @@ static int segments_x_ray(double X, double Y, const struct line_pnts *Points)
 
    \return 0 - outside
    \return 1 - inside 
-   \return 2 - on the boundary (exactly may be said only for vertex of vertical/horizontal line)
+   \return 2 - on the boundary
  */
 int Vect_point_in_poly(double X, double Y, const struct line_pnts *Points)
 {
@@ -682,7 +686,7 @@ int Vect_point_in_poly(double X, double Y, const struct line_pnts *Points)
 
    \return 0 - outside
    \return 1 - inside 
-   \return 2 - on the boundary (exactly may be said only for vertex of vertical/horizontal line)
+   \return 2 - on the boundary
  */
 int
 Vect_point_in_area_outer_ring(double X, double Y, const struct Map_info *Map,
@@ -692,12 +696,13 @@ Vect_point_in_area_outer_ring(double X, double Y, const struct Map_info *Map,
     int n_intersects, inter;
     int i, line;
     static struct line_pnts *Points;
-    struct bound_box lbox;
     const struct Plus_head *Plus;
     struct P_area *Area;
 
-    G_debug(3, "Vect_point_in_area_outer_ring(): x = %f y = %f area = %d", X,
-	    Y, area);
+    /* keep in sync with Vect_point_in_island() */
+
+    G_debug(3, "Vect_point_in_area_outer_ring(): x = %f y = %f area = %d",
+            X, Y, area);
 
     if (first == 1) {
 	Points = Vect_new_line_struct();
@@ -712,33 +717,28 @@ Vect_point_in_area_outer_ring(double X, double Y, const struct Map_info *Map,
 	return 0;
 
     n_intersects = 0;
-
     for (i = 0; i < Area->n_lines; i++) {
 	line = abs(Area->lines[i]);
-	G_debug(3, "  line[%d] = %d", i, line);
-
-	/* this is slow, but the fastest of all alternatives */
-	Vect_get_line_box(Map, line, &lbox);
 
-	/* slower as long as the spatial index is in memory: */
-	/*
 	Vect_read_line(Map, Points, NULL, line);
-	Vect_line_box(Points, &lbox);
-	*/
-	
-	/* dont check lines that obviously do not intersect with test ray */
-	if ((lbox.N < Y) || (lbox.S > Y) || (lbox.E < X))
+
+	/* if the bbox of the line would be available, 
+	 * the bbox could be used for a first check: */
+
+	/* Vect_line_box(Points, &lbox);
+	 * do not check lines that obviously do not intersect with test ray */
+	/* if ((lbox.N < Y) || (lbox.S > Y) || (lbox.E < X))
 	    continue;
+	 */
 
-	Vect_read_line(Map, Points, NULL, line);
+	/* retrieving the bbox from the spatial index or 
+	 * calculating the box from the vertices is slower than
+	 * just feeding the line to segments_x_ray() */
 
 	inter = segments_x_ray(X, Y, Points);
-	G_debug(3, "  inter = %d", inter);
-
 	if (inter == -1)
 	    return 2;
 	n_intersects += inter;
-	G_debug(3, "  n_intersects = %d", n_intersects);
     }
 
     /* odd number of intersections: inside, return 1 
@@ -756,7 +756,7 @@ Vect_point_in_area_outer_ring(double X, double Y, const struct Map_info *Map,
 
    \return 0 - outside
    \return 1 - inside 
-   \return 2 - on the boundary (exactly may be said only for vertex of vertical/horizontal line)
+   \return 2 - on the boundary
  */
 int Vect_point_in_island(double X, double Y, const struct Map_info *Map,
                          int isle, struct bound_box *box)
@@ -765,11 +765,13 @@ int Vect_point_in_island(double X, double Y, const struct Map_info *Map,
     int n_intersects, inter;
     int i, line;
     static struct line_pnts *Points;
-    struct bound_box lbox;
     const struct Plus_head *Plus;
     struct P_isle *Isle;
 
-    G_debug(3, "Vect_point_in_island(): x = %f y = %f isle = %d", X, Y, isle);
+    /* keep in sync with Vect_point_in_area_outer_ring() */
+
+    G_debug(3, "Vect_point_in_island(): x = %f y = %f isle = %d",
+            X, Y, isle);
 
     if (first == 1) {
 	Points = Vect_new_line_struct();
@@ -779,6 +781,7 @@ int Vect_point_in_island(double X, double Y, const struct Map_info *Map,
     Plus = &(Map->plus);
     Isle = Plus->Isle[isle];
 
+    /* First it must be in box */
     if (X < box->W || X > box->E || Y > box->N || Y < box->S)
 	return 0;
 
@@ -786,20 +789,20 @@ int Vect_point_in_island(double X, double Y, const struct Map_info *Map,
     for (i = 0; i < Isle->n_lines; i++) {
 	line = abs(Isle->lines[i]);
 
-	/* this is slow, but the fastest of all alternatives */
-	Vect_get_line_box(Map, line, &lbox);
-
-	/* slower as long as the spatial index is in memory: */
-	/*
 	Vect_read_line(Map, Points, NULL, line);
-	Vect_line_box(Points, &lbox);
-	*/
-	
-	/* dont check lines that obviously do not intersect with test ray */
-	if ((lbox.N < Y) || (lbox.S > Y) || (lbox.E < X))
+
+	/* if the bbox of the line would be available, 
+	 * the bbox could be used for a first check: */
+
+	/* Vect_line_box(Points, &lbox);
+	 * dont check lines that obviously do not intersect with test ray */
+	/* if ((lbox.N < Y) || (lbox.S > Y) || (lbox.E < X))
 	    continue;
+	 */
 
-	Vect_read_line(Map, Points, NULL, line);
+	/* retrieving the bbox from the spatial index or 
+	 * calculating the box from the vertices is slower than
+	 * just feeding the line to segments_x_ray() */
 
 	inter = segments_x_ray(X, Y, Points);
 	if (inter == -1)