GRASS GIS 8 Programmer's Manual
8.4.0dev(2024)5f6977e40c

Vector library  vector feature geometry. More...
Go to the source code of this file.
Functions  
struct line_pnts *  Vect__new_line_struct (void) 
Creates and initializes a struct line_pnts (internal use only) More...  
struct line_pnts *  Vect_new_line_struct (void) 
Creates and initializes a line_pnts structure. More...  
void  Vect_destroy_line_struct (struct line_pnts *p) 
Frees all memory associated with a line_pnts structure, including the structure itself. More...  
int  Vect_copy_xyz_to_pnts (struct line_pnts *Points, const double *x, const double *y, const double *z, int n) 
Copy points from array to line_pnts structure. More...  
void  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_get_point (const struct line_pnts *Points, int index, double *x, double *y, double *z) 
Get line point of given index. More...  
int  Vect_get_num_line_points (const struct line_pnts *Points) 
Get number of line points. 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, const struct line_pnts *APoints, int direction) 
Appends points to the end of a line. More...  
int  Vect_copy_pnts_to_xyz (const 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 (const 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 (const struct line_pnts *InPoints, double start, double end, struct line_pnts *OutPoints) 
Create line segment. More...  
double  Vect_line_length (const struct line_pnts *Points) 
Calculate line length, 3Dlength in case of 3D vector line. More...  
double  Vect_line_geodesic_length (const struct line_pnts *Points) 
Calculate line length. More...  
int  Vect_line_distance (const 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 distance of point to line. More...  
int  Vect_line_geodesic_distance (const 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 geodesic distance of point to line in meters. 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...  
void  Vect_line_box (const struct line_pnts *Points, struct 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...  
Vector library  vector feature geometry.
(C) 20012009 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.
Definition in file line.c.
struct line_pnts * Vect__new_line_struct  (  void  ) 
Creates and initializes a struct line_pnts (internal use only)
Use Vect_new_line_struct() instead.
Definition at line 55 of file line.c.
References line_pnts::alloc_points, malloc(), line_pnts::n_points, NULL, line_pnts::x, line_pnts::y, and line_pnts::z.
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.
If you are reusing a line struct, be sure to clear out old data first by calling Vect_reset_line().
Calls G_fatal_error() when out of memory.
Points  pointer to line_pnts structure 
x,y,z  point coordinates to be added 
int Vect_append_points  (  struct line_pnts *  Points, 
const struct line_pnts *  APoints,  
int  direction  
) 
Appends points to the end of a line.
Note, this will append to whatever is in line_pnts structure. If you are reusing a line struct, be sure to clear out old data first by calling Vect_reset_line().
Points  pointer to line_pnts structure 
APoints  points to be included 
direction  direction (GV_FORWARD, GV_BACKWARD) 
int Vect_copy_pnts_to_xyz  (  const struct line_pnts *  Points, 
double *  x,  
double *  y,  
double *  z,  
int *  n  
) 
int Vect_copy_xyz_to_pnts  (  struct line_pnts *  Points, 
const double *  x,  
const double *  y,  
const double *  z,  
int  n  
) 
void Vect_destroy_line_struct  (  struct line_pnts *  p  ) 
Frees all memory associated with a line_pnts structure, including the structure itself.
p  pointer to line_pnts structure 
Definition at line 77 of file line.c.
References line_pnts::alloc_points, G_free(), line_pnts::x, line_pnts::y, and line_pnts::z.
Referenced by Vect__free_cache(), and vector2perimeters().
int Vect_get_line_cat  (  struct Map_info *  Map, 
int  line,  
int  field  
) 
int Vect_get_num_line_points  (  const struct line_pnts *  Points  ) 
int Vect_line_delete_point  (  struct line_pnts *  Points, 
int  index  
) 
int Vect_line_distance  (  const 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 distance of point to line.
Sets (if not null):
points  pointer to line_pnts structure  
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 to point on line from segment beginning 
[out]  lpdist  distance to point on line from line beginning along line 
Definition at line 648 of file line.c.
References dig_distance2_point_to_line(), line_pnts::n_points, NULL, line_pnts::x, line_pnts::y, and line_pnts::z.
int Vect_line_geodesic_distance  (  const 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 geodesic distance of point to line in meters.
Sets (if not null):
points  pointer to line_pnts structure  
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 to point on line from segment beginning 
[out]  lpdist  distance to point on line from line beginning along line 
Definition at line 751 of file line.c.
References dig_distance2_point_to_line(), G_begin_distance_calculations(), G_distance(), line_pnts::n_points, NULL, line_pnts::x, line_pnts::y, and line_pnts::z.
double Vect_line_geodesic_length  (  const struct line_pnts *  Points  ) 
int Vect_line_get_point  (  const struct line_pnts *  Points, 
int  index,  
double *  x,  
double *  y,  
double *  z  
) 
Get line point of given index.
Calls G_fatal_error() when index is not range in.
Points  pointer to line_pnts structure 
index  point index (from 0 to Points>n_points1) 
x  pointer to x coordinate or NULL 
y  pointer to y coordinate or NULL 
z  pointer to z coordinate or NULL 
int Vect_line_insert_point  (  struct line_pnts *  Points, 
int  index,  
double  x,  
double  y,  
double  z  
) 
double Vect_line_length  (  const struct line_pnts *  Points  ) 
Calculate line length, 3Dlength in case of 3D vector line.
For LatLong use Vect_line_geodesic_length() instead.
Points  pointer to line_pnts structure geometry 
int Vect_line_prune  (  struct line_pnts *  Points  ) 
Remove duplicate points, i.e. zero length segments.
Points  pointer to line_pnts structure 
Definition at line 279 of file line.c.
Referenced by Vect_build_line_area().
int Vect_line_prune_thresh  (  struct line_pnts *  Points, 
double  threshold  
) 
void Vect_line_reverse  (  struct line_pnts *  Points  ) 
int Vect_line_segment  (  const 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.
InPoints  input line 
start  segment number 
end  segment number 
OutPoints  output line 
struct line_pnts* Vect_new_line_struct  (  void  ) 
Creates and initializes a line_pnts structure.
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().
Calls G_fatal_error() on error.
Definition at line 45 of file line.c.
References _, G_fatal_error(), NULL, and Vect__new_line_struct().
Referenced by Vect__reallocate_cache(), Vect_build_line_area(), Vect_point_buffer2(), and vector2perimeters().
int Vect_point_on_line  (  const 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 beginning, measured along line.
If the distance is greater than line length or negative, error is returned.
Points  pointer to line_pnts structure 
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) 
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.
x1,y1,z1  first point 
x2,y2,z2  second point 
with_z  use z coordinate 
Definition at line 866 of file line.c.
Referenced by Vect_find_node(), and Vedit_get_min_distance().
void Vect_reset_line  (  struct line_pnts *  Points  ) 
Reset line.
Make sure line structure is clean to be reused, i.e. it has no points associated with it Points must have previously been created with Vect_new_line_struct().
Points  pointer to line_pnts structure to be reset 
Definition at line 129 of file line.c.
Referenced by Vect__get_area_points_pg(), Vect_get_area_points(), and Vect_get_isle_points().