1 /* gEDA - GPL Electronic Design Automation
2 * libgeda - gEDA's library
3 * Copyright (C) 1998-2010 Ales Hvezda
4 * Copyright (C) 1998-2010 gEDA Contributors (see ChangeLog for details)
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /*! \file m_circle.c
22 *
23 * \brief Low-level mathmatical functions for circles
24 */
25
26 #include <config.h>
27 #include <math.h>
28 #include <stdio.h>
29
30 #include "libgeda_priv.h"
31
32 #ifdef HAVE_LIBDMALLOC
33 #include <dmalloc.h>
34 #endif
35
36
37 /*! \brief Calculates the distance between the given point and the closest
38 * point on the perimeter or interior of the circle.
39 *
40 * \param [in] circle The circle.
41 * \param [in] x The x coordinate of the given point.
42 * \param [in] y The y coordinate of the given point.
43 * \param [in] solid TRUE if the circle should be treated as solid, FALSE if
44 * the circle should be treated as hollow.
45 * \return The shortest distance from the circle to the point. With a solid
46 * shape, this function returns a distance of zero for interior points. With
47 * an invalid parameter, this function returns G_MAXDOUBLE.
48 */
m_circle_shortest_distance(CIRCLE * circle,int x,int y,int solid)49 double m_circle_shortest_distance (CIRCLE *circle, int x, int y, int solid)
50 {
51 double shortest_distance;
52 double distance_to_center;
53 double dx, dy;
54
55 g_return_val_if_fail (circle != NULL, G_MAXDOUBLE);
56
57 dx = ((double)x) - ((double)circle->center_x);
58 dy = ((double)y) - ((double)circle->center_y);
59
60 distance_to_center = sqrt ((dx * dx) + (dy * dy));
61
62 if (solid) {
63 shortest_distance = max (distance_to_center - circle->radius, 0);
64 } else {
65 shortest_distance = fabs (distance_to_center - circle->radius);
66 }
67
68 return shortest_distance;
69 }
70