GRASS: line.c File Reference

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Functions
line_pnts *	Vect__new_line_struct (void)
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
int	Vect_destroy_line_struct (struct line_pnts *p)
	frees all memory associated with a struct line_pnts, including the struct itself
int	Vect_copy_xyz_to_pnts (struct line_pnts Points, double x, double y, double z, int n)
	ADD.
int	Vect_reset_line (struct line_pnts *Points)
	ADD. 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 ().
int	Vect_append_point (struct line_pnts *Points, double x, double y, double z)
	appends one point to the end of a Points structure 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 ()
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
int	Vect_line_delete_point (struct line_pnts *Points, int index)
	delete point at given index and move all points above down
int	Vect_line_prune (struct line_pnts *Points)
	remove duplicate points, i.e. zero length segments
int	Vect_line_prune_thresh (struct line_pnts *Points, double threshold)
	remove points in threshold
int	Vect_append_points (struct line_pnts Points, struct line_pnts APoints, int direction)
	appends points to the end of a Points structure. 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 ()
int	Vect_copy_pnts_to_xyz (struct line_pnts Points, double x, double y, double z, int *n)
	ADD. NOTE! x/y arrays MUST be at least as large as Points->n_points.
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.
int	Vect_line_segment (struct line_pnts InPoints, double start, double end, struct line_pnts OutPoints)
	Create segment of InPoints from start to end measured along the line and write it to OutPoints.
double	Vect_line_length (struct line_pnts *Points)
	calculate line length, 3D-length in case of 3D vector line
double	Vect_line_geodesic_length (struct line_pnts *Points)
	calculate line length. If projection is LL, the length is measured along the geodesic.
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
double	Vect_points_distance (double x1, double y1, double z1, double x2, double y2, double z2, int with_z)
	distance of 2 points. with_z - use z coordinate
int	Vect_line_box (struct line_pnts Points, BOUND_BOX Box)
	get bounding box of line
void	Vect_line_reverse (struct line_pnts *Points)
	reverse the order of vertices
int	Vect_get_line_cat (struct Map_info *Map, int line, int field)
	fetches FIRST category number for given vector line and field

Function Documentation

struct line_pnts * Vect__new_line_struct ( void )

Definition at line 46 of file line.c.

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 Points structure 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 ()

Returns:: number of points

Parameters:

line_pnts

* structure, x, y, z

Definition at line 143 of file line.c.

References dig_alloc_points().

Referenced by clean_parallel(), parallel_line(), Vect__intersect_line_with_poly(), Vect_break_lines(), Vect_break_polygons(), Vect_clean_small_angles_at_nodes(), Vect_line_buffer(), Vect_line_segment(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor(), and Vect_snap_lines().

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

appends points to the end of a Points structure. 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 ()

Returns:: new number of points, -1 on out of memory

Parameters:

line_pnts

* structure, line_pntsA * structure, direction (GV_FORWARD, GV_BACKWARD)

Definition at line 278 of file line.c.

References dig_alloc_points().

Referenced by Vect_build_line_area(), Vect_get_area_points(), Vect_get_isle_points(), Vect_line_buffer(), and Vect_net_shortest_path_coor().

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

ADD. NOTE! x/y arrays MUST be at least as large as Points->n_points.

Returns:: number of points copied. Also note that n is a pointer to int.

Parameters:

line_pnts

* structure, x, y, z

Definition at line 318 of file line.c.

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

ADD.

Returns:: 0 on success, -1 on out of memory

Parameters:

line_pnts

* structure, x, y, z, number of points

Definition at line 93 of file line.c.

References dig_alloc_points().

Referenced by parallel_line().

int Vect_destroy_line_struct ( struct line_pnts * p )

frees all memory associated with a struct line_pnts, including the struct itself

Returns:: no return value

Parameters:

line_pnts

* structure

Definition at line 69 of file line.c.

Referenced by Vect_break_lines(), Vect_copy_map_lines(), Vect_get_area_area(), and Vect_snap_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:

	vmap,:	Map input
	varea,:	line number
	vfield,:	field number

Returns:: -1 no category
category number (>=0)

Definition at line 735 of file line.c.

References 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

Returns:: 0 on success, ADD on error

Parameters:

line_pnts

* structure, BOUND_BOX

Definition at line 692 of file line.c.

References dig_line_box().

Referenced by V1_read_next_line_nat(), 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

Returns:: number of points

Parameters:

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

Definition at line 199 of file line.c.

Referenced by Vect_clean_small_angles_at_nodes().

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

Returns:: nearest segment (first is 1)

Parameters:

line_pnts

* structure, x, y, z of point, flag if to use z coordinate, (3D calculation), point on line, distance to line, distance of point from segment beginning, distance of point from line beginning

Definition at line 567 of file line.c.

References dig_distance2_point_to_line().

Referenced by Vect_find_line(), Vect_line_check_intersection(), Vect_net_nearest_nodes(), and Vect_net_shortest_path_coor().

double Vect_line_geodesic_length ( struct line_pnts * Points )

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

Returns:: line length

Parameters:

line_pnts

* structure

Definition at line 521 of file line.c.

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

Returns:: number of points or -1 on error (alocation)

Parameters:

	Points	line structure
	index	(from 0 to Points->n_points-1)
	x
	y
	z

Definition at line 168 of file line.c.

References dig_alloc_points().

double Vect_line_length ( struct line_pnts * Points )

calculate line length, 3D-length in case of 3D vector line

Returns:: line length

Parameters:

line_pnts

* structure

Definition at line 496 of file line.c.

Referenced by remove_dangles(), Vect_area_perimeter(), Vect_line_segment(), Vect_net_build_graph(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor(), Vect_point_on_line(), and Vect_remove_small_areas().

int Vect_line_prune ( struct line_pnts * Points )

remove duplicate points, i.e. zero length segments

Returns:: number of points

Parameters:

Points

line structure

Definition at line 226 of file line.c.

Referenced by parallel_line(), Vect_break_lines(), Vect_break_polygons(), Vect_clean_small_angles_at_nodes(), Vect_line_buffer(), and Vect_snap_lines().

int Vect_line_prune_thresh	(	struct line_pnts *	Points,
		double	threshold
	)

remove points in threshold

Returns:: number of points in result

Parameters:

Points

line structure

Definition at line 255 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

Definition at line 704 of file line.c.

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

Create 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.

Returns:: 1 success 0 error when start > length or end < 0 or start < 0 or end > length

Parameters:

line_pnts

* structure, start, end, line_pnts * structure

Definition at line 445 of file line.c.

References Vect_append_point(), Vect_line_length(), Vect_point_on_line(), and Vect_reset_line().

struct line_pnts * Vect_new_line_struct ( void )

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

Returns:: struct line_pnts * or NULL on error

Parameters:

void

Definition at line 35 of file line.c.

References Vect__new_line_struct().

Referenced by clean_parallel(), remove_bridges(), remove_dangles(), V1_rewrite_line_nat(), Vect_break_lines(), Vect_break_polygons(), Vect_build_line_area(), Vect_clean_small_angles_at_nodes(), Vect_copy_map_lines(), Vect_find_island(), Vect_find_line(), 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_net_build_graph(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor(), Vect_overlay_and(), Vect_point_in_area_outer_ring(), Vect_point_in_island(), Vect_remove_duplicates(), Vect_remove_small_areas(), Vect_select_lines_by_polygon(), Vect_snap_lines(), and Vect_tin_get_z().

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.

( G_begin_distance_calculations() must be called before. - Is not true because G_distance is not used (no 3D support) )

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

Parameters:

line_pnts

* structure, distance, x, y, z, angle, slope

Definition at line 355 of file line.c.

References 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
	)

distance of 2 points. with_z - use z coordinate

Returns:: distance

Parameters:

x1,y1,z1,x2,y2,z2,with_z

Definition at line 666 of file line.c.

Referenced by Vect_clean_small_angles_at_nodes(), and Vect_find_node().

int Vect_reset_line ( struct line_pnts * Points )

ADD. 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 ().

Returns:: no return value

Parameters:

line_pnts

* structure

Definition at line 126 of file line.c.

Referenced by clean_parallel(), parallel_line(), Vect_break_lines(), Vect_break_polygons(), Vect_build_line_area(), Vect_clean_small_angles_at_nodes(), Vect_line_buffer(), Vect_line_segment(), Vect_net_nearest_nodes(), Vect_net_shortest_path_coor(), and Vect_snap_lines().

line.c File Reference

Functions

Function Documentation