line.c File Reference

Vector library - geometry manipulation. More...

#include <stdlib.h>
#include <math.h>
#include <grass/gis.h>
#include <grass/Vect.h>
#include <grass/glocale.h>

Include dependency graph for line.c:

Go to the source code of this file.

Functions
struct line_pnts *	Vect__new_line_struct (void)
	Creates and initializes a struct line_pnts. More...
struct line_pnts *	Vect_new_line_struct ()
	Creates and initializes a struct line_pnts. More...
int	Vect_destroy_line_struct (struct line_pnts *p)
	Frees all memory associated with a struct line_pnts, including the struct itself. More...
int	Vect_copy_xyz_to_pnts (struct line_pnts *Points, double *x, double *y, double *z, int n)
	Copy points from array to line structure. More...
int	Vect_reset_line (struct line_pnts *Points)
	Reset line. More...
int	Vect_append_point (struct line_pnts *Points, double x, double y, double z)
	Appends one point to the end of a line. More...
int	Vect_line_insert_point (struct line_pnts *Points, int index, double x, double y, double z)
	Insert new point at index position and move all old points at that position and above up. More...
int	Vect_line_delete_point (struct line_pnts *Points, int index)
	Delete point at given index and move all points above down. More...
int	Vect_line_prune (struct line_pnts *Points)
	Remove duplicate points, i.e. zero length segments. More...
int	Vect_line_prune_thresh (struct line_pnts *Points, double threshold)
	Remove points in threshold. More...
int	Vect_append_points (struct line_pnts *Points, struct line_pnts *APoints, int direction)
	Appends points to the end of a line. More...
int	Vect_copy_pnts_to_xyz (struct line_pnts *Points, double *x, double *y, double *z, int *n)
	Copy points from line structure to array. More...
int	Vect_point_on_line (struct line_pnts *Points, double distance, double *x, double *y, double *z, double *angle, double *slope)
	Find point on line in the specified distance. More...
int	Vect_line_segment (struct line_pnts *InPoints, double start, double end, struct line_pnts *OutPoints)
	Create line segment. More...
double	Vect_line_length (struct line_pnts *Points)
	Calculate line length, 3D-length in case of 3D vector line. More...
double	Vect_line_geodesic_length (struct line_pnts *Points)
	Calculate line length. More...
int	Vect_line_distance (struct line_pnts *points, double ux, double uy, double uz, int with_z, double *px, double *py, double *pz, double *dist, double *spdist, double *lpdist)
	calculate line distance. More...
double	Vect_points_distance (double x1, double y1, double z1, double x2, double y2, double z2, int with_z)
	Calculate distance of 2 points. More...
int	Vect_line_box (struct line_pnts *Points, BOUND_BOX *Box)
	Get bounding box of line. More...
void	Vect_line_reverse (struct line_pnts *Points)
	Reverse the order of vertices. More...
int	Vect_get_line_cat (struct Map_info *Map, int line, int field)
	Fetches FIRST category number for given vector line and field. More...

Detailed Description

Vector library - geometry manipulation.

(C) 2001-2008 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

Original author CERL, probably Dave Gerdes or Mike Higgins. Update to GRASS 5.7 Radim Blazek and David D. Gray.

Date

2001-2008

Definition in file line.c.

Function Documentation

struct line_pnts * Vect__new_line_struct

(

void

)

Creates and initializes a struct line_pnts.

Use Vect_new_line_struct() instead.

This structure is used for reading and writing vector lines and polygons. The library routines handle all memory allocation. If 3 lines in memory are needed at the same time, then simply 3 line_pnts structures have to be used.

Parameters

void

Returns

pointer to line_pnts

NULL on error

Definition at line 67 of file line.c.

References malloc(), and NULL.

Referenced by Vect_new_line_struct().

int Vect_append_point	(	struct line_pnts *	Points,
		double	x,
		double	y,
		double	z
	)

Appends one point to the end of a line.

Returns new number of points or -1 on out of memory Note, this will append to whatever is in line struct. If you are re-using a line struct, be sure to clear out old data first by calling Vect_reset_line().

Parameters

Points	line
x,y,z	point coordinates to be added

Returns

number of points

Definition at line 168 of file line.c.

References dig_alloc_points(), n, and y.

Referenced by wxdigit.IVDigit::EditLine(), G_site_put(), IL_check_at_points_2d(), wxdigit.IVDigit::InitCats(), wxdigit.IVDigit::MoveSelectedVertex(), NetA_add_point_on_node(), wxdisplay.DisplayDriver::SelectLinesByBox(), wxdigit.IVDigit::SelectLinesByQuery(), wxdigit.IVDigit::SplitLine(), V2_read_line_ogr(), Vect__intersect_line_with_poly(), Vect_break_lines_list(), Vect_break_polygons(), Vect_clean_small_angles_at_nodes(), Vect_line_buffer(), Vect_line_intersection(), Vect_line_segment(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor2(), Vect_point_buffer2(), Vect_snap_line(), Vect_snap_lines_list(), Vedit_bulk_labeling(), Vedit_merge_lines(), and Vedit_split_lines().

int Vect_append_points	(	struct line_pnts *	Points,
		struct line_pnts *	APoints,
		int	direction
	)

Appends points to the end of a line.

Note, this will append to whatever is in line struct. If you are re-using a line struct, be sure to clear out old data first by calling Vect_reset_line().

Parameters

Points	line
APoints	points to be included
direction	direction (GV_FORWARD, GV_BACKWARD)

Returns

new number of points

-1 on out of memory

Definition at line 312 of file line.c.

References dig_alloc_points(), and n.

Referenced by V1_read_next_line_ogr(), Vect_build_line_area(), Vect_get_area_points(), Vect_get_isle_points(), Vect_line_buffer(), Vect_merge_lines(), Vect_net_shortest_path_coor2(), and Vect_snap_line().

int Vect_copy_pnts_to_xyz	(	struct line_pnts *	Points,
		double *	x,
		double *	y,
		double *	z,
		int *	n
	)

Copy points from line structure to array.

x/y/z arrays MUST be at least as large as Points->n_points

Also note that n is a pointer to int.

Parameters

Points	line
x,y,z	coordinates arrays
n	number of points

Returns

number of points copied

Definition at line 359 of file line.c.

References n, and NULL.

int Vect_copy_xyz_to_pnts	(	struct line_pnts *	Points,
		double *	x,
		double *	y,
		double *	z,
		int	n
	)

Copy points from array to line structure.

Parameters

Points	line structure
x,y,z	coordinates
number	of points to be copied

Returns

0 on success

-1 on out of memory

Definition at line 115 of file line.c.

References dig_alloc_points(), n, and NULL.

Referenced by Vect_line_check_intersection().

int Vect_destroy_line_struct

(

struct line_pnts *

p

)

Frees all memory associated with a struct line_pnts, including the struct itself.

Parameters

p	pointer to line_pnts structure

Returns

0

Definition at line 90 of file line.c.

References G_free().

Referenced by wxdisplay.DisplayDriver::__del__(), wxdigit.IVDigit::__del__(), wxdisplay.DisplayDriver::GetDuplicates(), wxdigit.IVDigit::InitCats(), NetA_add_point_on_node(), wxdigit.IVDigit::OpenBackgroundMap(), wxdisplay.DisplayDriver::SelectLinesByBox(), V1_close_ogr(), Vect_area_buffer2(), Vect_break_lines_list(), Vect_copy_map_lines(), Vect_get_area_area(), Vect_line_buffer2(), Vect_line_intersection(), Vect_merge_lines(), Vect_snap_line(), Vect_snap_lines_list(), Vedit_add_vertex(), Vedit_bulk_labeling(), Vedit_chtype_lines(), Vedit_copy_lines(), Vedit_flip_lines(), Vedit_merge_lines(), Vedit_modify_cats(), Vedit_move_lines(), Vedit_move_vertex(), Vedit_remove_vertex(), Vedit_select_by_query(), Vedit_snap_lines(), Vedit_snap_point(), and Vedit_split_lines().

int Vect_get_line_cat	(	struct Map_info *	Map,
		int	line,
		int	field
	)

Fetches FIRST category number for given vector line and field.

Parameters

Map	vector map
line	line id
field	layer number

Returns

-1 no category

category number (>=0)

Definition at line 815 of file line.c.

References cat, G_debug(), NULL, Vect_cat_get(), Vect_new_cats_struct(), and Vect_read_line().

int Vect_line_box	(	struct line_pnts *	Points,
		BOUND_BOX *	Box
	)

Get bounding box of line.

Parameters

	Points	line
[out]	Box	bounding box

Returns

0

Definition at line 771 of file line.c.

References dig_line_box().

Referenced by V1_read_next_line_nat(), V1_read_next_line_ogr(), and Vect_remove_duplicates().

int Vect_line_delete_point	(	struct line_pnts *	Points,
		int	index
	)

Delete point at given index and move all points above down.

Parameters

Points	line
index	(from 0 to Points->n_points-1)

Returns

number of points

Definition at line 227 of file line.c.

References G_fatal_error(), and n.

Referenced by Vect_clean_small_angles_at_nodes(), and Vedit_remove_vertex().

int Vect_line_distance	(	struct line_pnts *	points,
		double	ux,
		double	uy,
		double	uz,
		int	with_z,
		double *	px,
		double *	py,
		double *	pz,
		double *	dist,
		double *	spdist,
		double *	lpdist
	)

calculate line distance.

Sets (if not null):

• px, py - point on line,
• dist - distance to line,
• spdist - distance to point on line from segment beginning,
• sldist - distance to point on line form line beginning along line

Parameters

	points	line
	ux,uy,uz	point coordinates
	with_z	flag if to use z coordinate (3D calculation)
[out]	px,py,pz	point on line
[out]	dist	distance to line,
[out]	spdist	distance of point from segment beginning
[out]	lpdist	distance of point from line

Returns

nearest segment (first is 1)

Definition at line 631 of file line.c.

References dig_distance2_point_to_line(), and NULL.

Referenced by Vect_find_line_list(), Vect_line_check_intersection(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor2(), Vedit_add_vertex(), and Vedit_split_lines().

double Vect_line_geodesic_length

(

struct line_pnts *

Points

)

Calculate line length.

If projection is LL, the length is measured along the geodesic.

Parameters

Points

line

Returns

line length

Definition at line 583 of file line.c.

References G_begin_distance_calculations(), and G_geodesic_distance().

Referenced by Vect_net_build_graph().

int Vect_line_insert_point	(	struct line_pnts *	Points,
		int	index,
		double	x,
		double	y,
		double	z
	)

Insert new point at index position and move all old points at that position and above up.

Parameters

Points	line
index	(from 0 to Points->n_points-1)
x,y,z	point coordinates

Returns

number of points

-1 on error (alocation)

Definition at line 194 of file line.c.

References dig_alloc_points(), G_fatal_error(), n, and y.

Referenced by Vedit_add_vertex().

double Vect_line_length

(

struct line_pnts *

Points

)

Calculate line length, 3D-length in case of 3D vector line.

For Lat-Long use Vect_line_geodesic_length() instead.

Parameters

Points

line

Returns

line length

Definition at line 555 of file line.c.

Referenced by wxdigit.IVDigit::GetLineLength(), Vect_area_perimeter(), Vect_line_segment(), Vect_net_build_graph(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor2(), Vect_point_on_line(), Vect_remove_small_areas(), Vedit_bulk_labeling(), and Vedit_split_lines().

int Vect_line_prune

(

struct line_pnts *

Points

)

Remove duplicate points, i.e. zero length segments.

Parameters

Points

line

Returns

number of points

Definition at line 255 of file line.c.

Referenced by Vect_area_buffer2(), Vect_break_lines_list(), Vect_break_polygons(), Vect_clean_small_angles_at_nodes(), Vect_line_buffer(), Vect_line_buffer2(), Vect_line_segment(), Vect_snap_line(), Vect_snap_lines_list(), and Vedit_add_vertex().

int Vect_line_prune_thresh	(	struct line_pnts *	Points,
		double	threshold
	)

Remove points in threshold.

Parameters

Points	line
threshold	threshold value

Returns

number of points in result

Definition at line 285 of file line.c.

References dig_prune().

void Vect_line_reverse

(

struct line_pnts *

Points

)

Reverse the order of vertices.

Parameters

Points

line to be changed

Returns

void

Definition at line 784 of file line.c.

References for(), int, and y.

Referenced by Vedit_flip_lines().

int Vect_line_segment	(	struct line_pnts *	InPoints,
		double	start,
		double	end,
		struct line_pnts *	OutPoints
	)

Create line segment.

Creates segment of InPoints from start to end measured along the line and write it to OutPoints.

If the distance is greater than line length or negative, error is returned.

Parameters

InPoints	input line
start	segment number
end	segment number
OutPoints	output line

Returns

1 success

0 error when start > length or end < 0 or start < 0 or end > length

Definition at line 497 of file line.c.

References G_debug(), G_warning(), NULL, Vect_append_point(), Vect_line_length(), Vect_line_prune(), Vect_point_on_line(), and Vect_reset_line().

struct line_pnts* Vect_new_line_struct

(

)

Creates and initializes a struct line_pnts.

This structure is used for reading and writing vector lines and polygons. The library routines handle all memory allocation. If 3 lines in memory are needed at the same time, then simply 3 line_pnts structures have to be used.

To free allocated memory call Vect_destroy_line_struct().

Parameters

void

Returns

pointer to line_pnts

NULL on error

Definition at line 57 of file line.c.

References G_fatal_error(), NULL, and Vect__new_line_struct().

Referenced by G_site_get(), G_site_put(), wxdisplay.DisplayDriver::GetDuplicates(), Gp_load_sites(), Gv_load_vect(), IL_vector_input_data_2d(), wxdigit.IVDigit::InitCats(), NetA_add_point_on_node(), NetA_get_node_costs(), wxdigit.IVDigit::OpenBackgroundMap(), wxdisplay.DisplayDriver::SelectLinesByBox(), V1_rewrite_line_nat(), V2_restore_line_nat(), Vect_area_buffer2(), Vect_break_lines_list(), Vect_break_polygons(), Vect_build_line_area(), Vect_build_nat(), Vect_clean_small_angles_at_nodes(), Vect_copy_map_lines(), Vect_find_island(), Vect_find_line_list(), Vect_get_area_area(), Vect_get_area_points(), Vect_get_isle_points(), Vect_get_point_in_area(), Vect_get_point_in_poly_isl(), Vect_isle_find_area(), Vect_line_buffer(), Vect_line_buffer2(), Vect_line_check_intersection(), Vect_line_intersection(), Vect_merge_lines(), Vect_net_build_graph(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor2(), Vect_overlay_and(), Vect_point_buffer2(), Vect_point_in_area_outer_ring(), Vect_point_in_island(), Vect_remove_duplicates(), Vect_remove_small_areas(), Vect_select_lines_by_polygon(), Vect_snap_line(), Vect_snap_lines_list(), Vect_tin_get_z(), Vedit_add_vertex(), Vedit_bulk_labeling(), Vedit_chtype_lines(), Vedit_copy_lines(), Vedit_flip_lines(), Vedit_merge_lines(), Vedit_modify_cats(), Vedit_move_lines(), Vedit_move_vertex(), Vedit_remove_vertex(), Vedit_select_by_query(), Vedit_snap_lines(), Vedit_snap_point(), and Vedit_split_lines().

int Vect_point_on_line	(	struct line_pnts *	Points,
		double	distance,
		double *	x,
		double *	y,
		double *	z,
		double *	angle,
		double *	slope
	)

Find point on line in the specified distance.

From the begining, measured along line.

If the distance is greater than line length or negative, error is returned.

Parameters

Points	line
distance	distance value
x,y,z	pointers to point coordinates or NULL
angle	pointer to angle of line in that point (radians, counter clockwise from x axis) or NULL
slope	pointer to slope angle in radians (positive up)

Returns

number of segment the point is on (first is 1),

0 error when point is outside the line

Definition at line 393 of file line.c.

References G_debug(), NULL, and Vect_line_length().

Referenced by Vect_line_segment().

double Vect_points_distance	(	double	x1,
		double	y1,
		double	z1,
		double	x2,
		double	y2,
		double	z2,
		int	with_z
	)

Calculate distance of 2 points.

Simply uses Pythagoras.

Parameters

x1,y1,z1	first point
x2,y2,z2	second point
with_z	use z coordinate

Returns

distance

Definition at line 745 of file line.c.

Referenced by wxdisplay.DisplayDriver::GetSelectedVertex(), wxdigit.IVDigit::InitCats(), Vect_clean_small_angles_at_nodes(), Vect_find_node(), Vedit_add_vertex(), Vedit_get_min_distance(), Vedit_move_vertex(), Vedit_remove_vertex(), Vedit_snap_line(), and Vedit_snap_point().

int Vect_reset_line

(

struct line_pnts *

Points

)

Reset line.

Make sure line structure is clean to be re-used, i.e. it has no points associated with it Points must have previously been created with Vect_new_line_struct().

Parameters

Points

line to be reset

Returns

0

Definition at line 148 of file line.c.

Referenced by wxdigit.IVDigit::EditLine(), G_site_put(), IL_check_at_points_2d(), wxdigit.IVDigit::InitCats(), wxdigit.IVDigit::MoveSelectedVertex(), NetA_add_point_on_node(), wxdigit.IVDigit::SelectLinesByQuery(), wxdigit.IVDigit::SplitLine(), V1_read_next_line_ogr(), V2_read_line_ogr(), Vect_break_lines_list(), Vect_break_polygons(), Vect_build_line_area(), Vect_clean_small_angles_at_nodes(), Vect_line_buffer(), Vect_line_segment(), Vect_merge_lines(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor2(), Vect_snap_line(), Vect_snap_lines_list(), Vedit_merge_lines(), and Vedit_split_lines().