buffer2.c File Reference

Vector library - nearest, adjust, parallel lines. More...

#include <stdlib.h>
#include <math.h>
#include <grass/gis.h>
#include <grass/vector.h>
#include <grass/glocale.h>
#include "dgraph.h"

Include dependency graph for buffer2.c:

Go to the source code of this file.

Macros
#define	LENGTH(DX, DY)   (sqrt((DX * DX) + (DY * DY)))
#define	PI   M_PI
#define	RIGHT_SIDE   1
#define	LEFT_SIDE   -1
#define	LOOPED_LINE   1
#define	NON_LOOPED_LINE   0

Functions
void	Vect_line_buffer2 (const struct line_pnts *Points, double da, double db, double dalpha, int round, int caps, double tol, struct line_pnts **oPoints, struct line_pnts ***iPoints, int *inner_count)
	Creates buffer around line. More...
void	Vect_area_buffer2 (struct Map_info *Map, int area, double da, double db, double dalpha, int round, int caps, double tol, struct line_pnts **oPoints, struct line_pnts ***iPoints, int *inner_count)
	Creates buffer around area. More...
void	Vect_point_buffer2 (double px, double py, double da, double db, double dalpha, int round, double tol, struct line_pnts **oPoints)
	Creates buffer around the point (px, py). More...
void	Vect_line_parallel2 (struct line_pnts *InPoints, double da, double db, double dalpha, int side, int round, double tol, struct line_pnts *OutPoints)

Detailed Description

Vector library - nearest, adjust, parallel lines.

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

Original author Radim Blazek (see buffer.c)

Rewritten by Rosen Matev (Google Summer of Code 2008)

Definition in file buffer2.c.

Macro Definition Documentation

LEFT_SIDE

#define LEFT_SIDE   -1

Definition at line 30 of file buffer2.c.

LENGTH

#define LENGTH	(		DX,
			DY
	)		(sqrt((DX * DX) + (DY * DY)))

Definition at line 27 of file buffer2.c.

LOOPED_LINE

#define LOOPED_LINE   1

Definition at line 31 of file buffer2.c.

NON_LOOPED_LINE

#define NON_LOOPED_LINE   0

Definition at line 32 of file buffer2.c.

PI

#define PI   M_PI

Definition at line 28 of file buffer2.c.

RIGHT_SIDE

#define RIGHT_SIDE   1

Definition at line 29 of file buffer2.c.

Function Documentation

Vect_area_buffer2()

void Vect_area_buffer2	(	struct Map_info *	Map,
		int	area,
		double	da,
		double	db,
		double	dalpha,
		int	round,
		int	caps,
		double	tol,
		struct line_pnts **	oPoints,
		struct line_pnts ***	iPoints,
		int *	inner_count
	)

Creates buffer around area.

Parameters

	Map	vector map
	area	area id
	da	distance along major axis
	db	distance along minor axis
	dalpha	angle between 0x and major axis
	round	make corners round
	caps	add caps at line ends
	tol	maximum distance between theoretical arc and output segments
[out]	oPoints	output polygon outer border (ccw order)
[out]	inner_count	number of holes
[out]	iPoints	array of output polygon's holes (cw order)

Definition at line 1074 of file buffer2.c.

Vect_line_buffer2()

void Vect_line_buffer2	(	const struct line_pnts *	Points,
		double	da,
		double	db,
		double	dalpha,
		int	round,
		int	caps,
		double	tol,
		struct line_pnts **	oPoints,
		struct line_pnts ***	iPoints,
		int *	inner_count
	)

Creates buffer around line.

See also Vect_line_buffer().

Shape of buffer endings is managed by two parameters - round and cap. Setting round=1, cap=1 gives "classical" buffer, while round=0, cap=1 gives square end, but cap=0 – butt. See v.buffer manual or SVG stroke-linecap for examples.

To get "classical" buffer, set db equal to da, and dalpha to 0.

Parameters

	Points	input line geometry
	da	distance along major axis
	db	distance along minor axis
	dalpha	angle between 0x and major axis
	round	make corners round (0 - square, not 0 - round)
	caps	add caps at line ends (0 - butt, not 0 - caps)
	tol	maximum distance between theoretical arc and output segments
[out]	oPoints	output polygon outer border (ccw order)
[out]	iPoints	array of output polygon's holes (cw order)
[out]	inner_count	number of holes

Definition at line 1009 of file buffer2.c.

Vect_line_parallel2()

void Vect_line_parallel2	(	struct line_pnts *	InPoints,
		double	da,
		double	db,
		double	dalpha,
		int	side,
		int	round,
		double	tol,
		struct line_pnts *	OutPoints
	)

Definition at line 1191 of file buffer2.c.

References G_debug(), and line_pnts::n_points.

Vect_point_buffer2()

void Vect_point_buffer2	(	double	px,
		double	py,
		double	da,
		double	db,
		double	dalpha,
		int	round,
		double	tol,
		struct line_pnts **	oPoints
	)

Creates buffer around the point (px, py).

Parameters

	px	input point x-coordinate
	py	input point y-coordinate
	da	distance along major axis
	db	distance along minor axis
	dalpha	angle between 0x and major axis
	round	make corners round
	tol	maximum distance between theoretical arc and output segments
[out]	oPoints	output polygon outer border (ccw order)

Note

Currently only handles buffers with rounded corners (round = 1)

Definition at line 1141 of file buffer2.c.

References G_debug(), PI, and Vect_new_line_struct().