Vector library - update topo for areas (lower level functions) More...

#include <stdlib.h>
#include <grass/vector.h>
#include <grass/glocale.h>

Include dependency graph for plus_area.c:

Functions
int	dig_build_area_with_line (struct Plus_head plus, plus_t first_line, int side, plus_t *lines)
	Build topo for area from lines. More...

int	dig_add_area (struct Plus_head plus, int n_lines, plus_t lines, struct bound_box *box)
	Allocate space for new area and create boundary info from array. More...

int	dig_area_add_isle (struct Plus_head *plus, int area, int isle)
	Add isle to area if does not exist yet. More...

int	dig_area_del_isle (struct Plus_head *plus, int area, int isle)
	Delete isle from area. More...

int	dig_del_area (struct Plus_head *plus, int area)
	Delete area from Plus_head structure. More...

int	dig_angle_next_line (struct Plus_head plus, plus_t current_line, int side, int type, float angle)
	Find line number of next angle to follow a line. More...

int	dig_node_angle_check (struct Plus_head *plus, plus_t line, int type)
	Check if angles of adjacent lines differ. More...

int	dig_add_isle (struct Plus_head plus, int n_lines, plus_t lines, struct bound_box *box)
	Allocate space for new island and create boundary info from array. More...

int	dig_del_isle (struct Plus_head *plus, int isle)
	Delete island from Plus_head structure. More...

Detailed Description

Vector library - update topo for areas (lower level functions)

Lower level functions for reading/writing/manipulating vectors.

This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

Author: CERL (probably Dave Gerdes), Radim Blazek

Date: 2001-2006

Definition in file plus_area.c.

Function Documentation

◆ dig_add_area()

int dig_add_area	(	struct Plus_head *	plus,
		int	n_lines,
		plus_t *	lines,
		struct bound_box *	box
	)

Allocate space for new area and create boundary info from array.

Then for each line in area, update line (right,left) info.

Neither islands nor centroids are filled.

Parameters

[in]	plus	pointer to Plus_head structure
[in]	n_lines	number of lines
[in]	lines	array of lines, negative for reverse direction
[in]	box	bounding box

Returns: number of new area; -1 on error

Definition at line 184 of file plus_area.c.

Referenced by Vect_build_line_area().

◆ dig_add_isle()

int dig_add_isle	(	struct Plus_head *	plus,
		int	n_lines,
		plus_t *	lines,
		struct bound_box *	box
	)

Allocate space for new island and create boundary info from array.

The order of input lines is expected to be counter clockwise. Then for each line in isle, update line (right,left) info.

Area number the island is within is not filled.

Parameters

[in]	plus	pointer to Plus_head structure
[in]	n_lines	number of lines
[in]	lines	array of lines, negative for reverse direction
[in]	box	bounding box

Returns: number of new isle; -1 on error

Definition at line 682 of file plus_area.c.

Referenced by Vect_build_line_area().

◆ dig_angle_next_line()

int dig_angle_next_line	(	struct Plus_head *	plus,
		plus_t	current_line,
		int	side,
		int	type,
		float *	angle
	)

Find line number of next angle to follow a line.

Assume that lines are sorted in increasing angle order and angles of points and degenerated lines are set to -9 (ignored).

Parameters

[in]	plus	pointer to Plus_head structure
[in]	current_line	current line id, negative if request for end node
[in]	side	side GV_RIGHT or GV_LEFT
[in]	type	line type (GV_LINE, GV_BOUNDARY or both)
[in]	angle

Returns: line number of next angle to follow a line (negative if connected by end node) (number of current line may be returned if dangle - this is used in build); 0 on error or not found

Definition at line 466 of file plus_area.c.

◆ dig_area_add_isle()

int dig_area_add_isle	(	struct Plus_head *	plus,
		int	area,
		int	isle
	)

Add isle to area if does not exist yet.

Parameters

[in]	plus	pointer to Plus_head structure
[in]	area	area id
[in]	isle	isle id

Returns: 0

Definition at line 258 of file plus_area.c.

References G_debug().

Referenced by Vect_attach_isle().

◆ dig_area_del_isle()

int dig_area_del_isle	(	struct Plus_head *	plus,
		int	area,
		int	isle
	)

Delete isle from area.

Parameters

[in]	plus	pointer to Plus_head structure
[in]	area	area id
[in]	isle	isle id

Returns: 0

Definition at line 307 of file plus_area.c.

References _, Plus_head::Area, G_debug(), G_fatal_error(), P_area::isles, P_area::n_isles, and NULL.

Referenced by Vect_attach_isles().

◆ dig_build_area_with_line()

int dig_build_area_with_line	(	struct Plus_head *	plus,
		plus_t	first_line,
		int	side,
		plus_t **	lines
	)

Build topo for area from lines.

Area is built in clockwise order. Take a given line and start off to the RIGHT/LEFT and try to complete an area.

Possible Scenarios:

I. path runs into first line. : AREA!
II. path runs into a dead end (no other area lines at node) : no area
III. path runs into a previous line that is not 1st line or to 1st line but not to start node : no area

After we find an area then we call point_in_area() to see if the specified point is w/in the area

Old returns -1: error 0: no area (1: point in area) -2: island !!

Parameters

[in]	plus	pointer to Plus_head structure
[in]	first_line	line id of first line
[in]	side	side of line to build area on (GV_LEFT \| GV_RIGHT)
[in]	lines	pointer to array of lines

Returns: -1 on error; 0 no area; number of lines

Definition at line 51 of file plus_area.c.

References P_isle::n_lines.

Referenced by Vect_build_line_area().

◆ dig_del_area()

int dig_del_area	(	struct Plus_head *	plus,
		int	area
	)

Delete area from Plus_head structure.

This function deletes area from the topo structure and resets references to this area in boundaries, isles (within), and the centroid (if any) to 0. Possible new area is not created by this function, so that old boundaries participating in this area are left without area information even if form new area. Not enabled now: If area is inside other area, area info for islands within deleted area is reset to that area outside. (currently area info of isles is set to 0)

Parameters

[in]	plus	pointer to Plus_head structure
[in]	area	area id

Returns: 0 on error; 1 on success

Definition at line 357 of file plus_area.c.

◆ dig_del_isle()

int dig_del_isle	(	struct Plus_head *	plus,
		int	isle
	)

Delete island from Plus_head structure.

Reset references to it in lines and area outside.

Parameters

[in]	plus	pointer to Plus_head structure
[in]	isle	isle id

Returns: 1

Definition at line 757 of file plus_area.c.

◆ dig_node_angle_check()

int dig_node_angle_check	(	struct Plus_head *	plus,
		plus_t	line,
		int	type
	)

Check if angles of adjacent lines differ.

Negative line number for end point. Assume that lines are sorted in increasing angle order and angles of points and degenerated lines are set to 9 (ignored).

Parameters

[in]	plus	pointer to Plus_head structure
[in]	line	current line id, negative if request for node 2
[in]	type	line type (GV_LINE, GV_BOUNDARY or both)

Returns: 1 angles differ; 0 angle of a line up or down is identical

Definition at line 607 of file plus_area.c.

Functions

Detailed Description

Function Documentation

◆ dig_add_area()

◆ dig_add_isle()

◆ dig_angle_next_line()

◆ dig_area_add_isle()

◆ dig_area_del_isle()

◆ dig_build_area_with_line()

◆ dig_del_area()

◆ dig_del_isle()

◆ dig_node_angle_check()