Geografic-Information-System/lib/vector/diglib/inside.c

/*
****************************************************************************
*
* MODULE:       Vector library 
*   	    	
* AUTHOR(S):    Original author CERL, probably Dave Gerdes.
*               Update to GRASS 5.7 Radim Blazek.
*
* PURPOSE:      Lower level functions for reading/writing/manipulating vectors.
*
* COPYRIGHT:    (C) 2001 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.
*
*****************************************************************************/
#include <grass/gis.h>
#include <grass/Vect.h>

double 
dig_x_intersect (
		  double beg_x,
		  double end_x,
		  double beg_y,
		  double end_y,
		  double Y)
{
  double b, a;

  b = (end_x - beg_x) / (end_y - beg_y);
  a = beg_x - b * beg_y;
  return (a + b * Y);
}

int 
dig_in_area_bbox (
		   P_AREA * Area,
		   double x, double y)
{
#ifdef GDEBUG
   G_debug (3, "BBOX: (x,y) (%lf, %lf)\n", x, y);
   G_debug (3, "NSEW:  %lf, %lf, %lf, %lf\n", Area->N, Area->S, Area->E, Area->W);
#endif
  if (x < Area->W)
    return (0);
  if (x > Area->E)
    return (0);
  if (y < Area->S)
    return (0);
  if (y > Area->N)
    return (0);

  return (1);
}