[GRASS-SVN] r43532 - grass/branches/develbranch_6/lib/vector/Vlib
svn_grass at osgeo.org
svn_grass at osgeo.org
Mon Sep 20 04:02:51 EDT 2010
Author: mmetz
Date: 2010-09-20 08:02:51 +0000 (Mon, 20 Sep 2010)
New Revision: 43532
Added:
grass/branches/develbranch_6/lib/vector/Vlib/merge_lines.c
Log:
add cleaning function for vector import
Added: grass/branches/develbranch_6/lib/vector/Vlib/merge_lines.c
===================================================================
--- grass/branches/develbranch_6/lib/vector/Vlib/merge_lines.c (rev 0)
+++ grass/branches/develbranch_6/lib/vector/Vlib/merge_lines.c 2010-09-20 08:02:51 UTC (rev 43532)
@@ -0,0 +1,199 @@
+/*!
+ \file merge_lines.c
+
+ \brief Vector library - clean geometry (merge lines/boundaries)
+
+ Higher level functions for reading/writing/manipulating vectors.
+
+ (C) 2001-2009 by the GRASS Development Team
+
+ This program is free software under the
+ GNU General Public License (>=v2).
+ Read the file COPYING that comes with GRASS
+ for details.
+
+ \author Markus Metz
+ */
+
+#include <grass/config.h>
+#include <stdlib.h>
+#include <math.h>
+#include <grass/gis.h>
+#include <grass/Vect.h>
+#include <grass/glocale.h>
+
+/*!
+ \brief Merge lines or boundaries in vector map.
+
+ Merges lines specified by type in vector map.
+ Useful for generalization and smoothing.
+ Adjacent boundaries are merged as long as topology is maintained.
+ Adjacent lines are merged as long as there are exactly two different
+ lines connected at a given node.
+ Categories are added up when merging.
+ GV_BUILD_BASE as topo build level is sufficient, areas need not be built.
+
+ \param Map input vector map
+ \param type feature type
+ \param[out] Err vector map where merged lines/boundaries will be written or NULL
+ \param new_lines pointer to where number of new lines/boundaries is stored or NULL
+
+ \return number of merged lines/boundaries
+ */
+
+int Vect_merge_lines(struct Map_info *Map, int type, int *new_lines,
+ struct Map_info *Err)
+{
+ int line, nlines, i, c, first, last, next_line, curr_line;
+ int merged = 0, newl = 0;
+ int next_node, direction, node_n_lines, same_type;
+ struct Plus_head *Plus;
+ struct ilist *List;
+ struct line_pnts *MPoints, *Points;
+ struct line_cats *MCats, *Cats;
+ struct P_line *Line;
+
+ if ((type & GV_BOUNDARY) && (type & GV_LINE)) {
+ G_warning
+ ("Merging is done only with either lines or boundaries, not both types at the same time");
+ return 0;
+ }
+ if (!(type & GV_BOUNDARY) && !(type & GV_LINE)) {
+ G_warning
+ ("Merging is done with lines or boundaries only, not with other types");
+ return 0;
+ }
+
+ Plus = &(Map->plus);
+ nlines = Vect_get_num_lines(Map);
+
+ Points = Vect_new_line_struct();
+ Cats = Vect_new_cats_struct();
+ MPoints = Vect_new_line_struct();
+ MCats = Vect_new_cats_struct();
+ List = Vect_new_list();
+
+ for (line = 1; line <= nlines; line++) {
+ G_percent(line, nlines, 2);
+
+ if (!Vect_line_alive(Map, line))
+ continue;
+
+ Line = Plus->Line[line];
+
+ if (!(Line->type & type))
+ continue;
+
+ /* special cases:
+ * - loop back to start boundary via several other boundaries
+ * - one boundary forming closed loop
+ * - node with 3 entries but only 2 boundaries, one of them connecting twice,
+ * the other one must then be topologically incorrect in case of boundary */
+
+ /* go backward as long as there is only one other line/boundary at the current node */
+ G_debug(3, "go backward");
+ next_node = Line->N1;
+ first = -line;
+ while (1) {
+ node_n_lines = Vect_get_node_n_lines(Map, next_node);
+ same_type = 0;
+ next_line = first;
+ for (i = 0; i < node_n_lines; i++) {
+ curr_line = Vect_get_node_line(Map, next_node, i);
+ if ((Plus->Line[abs(curr_line)]->type & type)) {
+ same_type++;
+ if (abs(curr_line) != abs(first))
+ next_line = curr_line;
+ }
+ }
+ if (same_type == 2 && abs(next_line) != abs(first) &&
+ abs(next_line) != line) {
+ first = next_line;
+
+ if (first < 0)
+ next_node = Plus->Line[-first]->N1;
+ else
+ next_node = Plus->Line[first]->N2;
+ }
+ else
+ break;
+ }
+
+ /* go forward as long as there is only one other line/boundary at the current node */
+ G_debug(3, "go forward");
+
+ /* reverse direction */
+ last = -first;
+
+ if (last < 0)
+ next_node = Plus->Line[-last]->N1;
+ else
+ next_node = Plus->Line[last]->N2;
+
+ Vect_reset_list(List);
+ while (1) {
+ Vect_list_append(List, last);
+ node_n_lines = Vect_get_node_n_lines(Map, next_node);
+ same_type = 0;
+ next_line = last;
+ for (i = 0; i < node_n_lines; i++) {
+ curr_line = Vect_get_node_line(Map, next_node, i);
+ if ((Plus->Line[abs(curr_line)]->type & type)) {
+ same_type++;
+ if (abs(curr_line) != abs(last))
+ next_line = curr_line;
+ }
+ }
+
+ if (same_type == 2 && abs(next_line) != abs(last) &&
+ abs(next_line) != abs(first)) {
+ last = next_line;
+
+ if (last < 0)
+ next_node = Plus->Line[-last]->N1;
+ else
+ next_node = Plus->Line[last]->N2;
+ }
+ else
+ break;
+ }
+
+ /* merge lines */
+ if (List->n_values > 1) {
+ G_debug(3, "merge %d lines", List->n_values);
+ Vect_reset_line(MPoints);
+ Vect_reset_cats(MCats);
+
+ for (i = 0; i < List->n_values; i++) {
+ Vect_reset_line(Points);
+ Vect_reset_cats(Cats);
+ Vect_read_line(Map, Points, Cats, abs(List->value[i]));
+ direction = (List->value[i] < 0 ? GV_BACKWARD : GV_FORWARD);
+ Vect_append_points(MPoints, Points, direction);
+ MPoints->n_points--;
+ for (c = 0; c < Cats->n_cats; c++) {
+ Vect_cat_set(MCats, Cats->field[c], Cats->cat[c]);
+ }
+ if (Err) {
+ /* write out lines/boundaries to be merged */
+ Vect_write_line(Err, type, Points, Cats);
+ }
+ Vect_delete_line(Map, abs(List->value[i]));
+ }
+ MPoints->n_points++;
+ Vect_write_line(Map, type, MPoints, MCats);
+ merged += List->n_values;
+ newl++;
+ }
+
+ nlines = Vect_get_num_lines(Map);
+ }
+
+ G_verbose_message(_("%d boundaries merged"), merged);
+ G_verbose_message(_("%d new boundaries"), newl);
+
+ if (new_lines)
+ *new_lines = newl;
+
+ return merged;
+}
Property changes on: grass/branches/develbranch_6/lib/vector/Vlib/merge_lines.c
___________________________________________________________________
Added: svn:keywords
+ Author Date Id
Added: svn:eol-style
+ native
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