Parent Directory | Revision Log
Map handles overwritten coordinates
1 | /* -*- Mode: C; indent-tabs-mode: nil; c-basic-offset: 4; tab-width: 4 -*- */ |
2 | /* vim:set et sw=4 ts=4 cino=t0,(0: */ |
3 | /* |
4 | * converter.c |
5 | * Copyright (C) Marcus Bauer 2008 <marcus.bauer@gmail.com> |
6 | * Copyright (C) John Stowers 2008 <john.stowers@gmail.com> |
7 | * |
8 | * osm-gps-map.c is free software: you can redistribute it and/or modify it |
9 | * under the terms of the GNU General Public License as published by the |
10 | * Free Software Foundation, either version 3 of the License, or |
11 | * (at your option) any later version. |
12 | * |
13 | * osm-gps-map.c is distributed in the hope that it will be useful, but |
14 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
16 | * See the GNU General Public License for more details. |
17 | * |
18 | * You should have received a copy of the GNU General Public License along |
19 | * with this program. If not, see <http://www.gnu.org/licenses/>. |
20 | */ |
21 | |
22 | #include <math.h> |
23 | #include <stdio.h> |
24 | |
25 | #include "osm-gps-map-types.h" |
26 | #include "converter.h" |
27 | |
28 | |
29 | float |
30 | deg2rad(float deg) |
31 | { |
32 | return (deg * M_PI / 180.0); |
33 | } |
34 | |
35 | float |
36 | rad2deg(float rad) |
37 | { |
38 | return (rad / M_PI * 180.0); |
39 | } |
40 | |
41 | |
42 | int |
43 | lat2pixel( int zoom, |
44 | float lat) |
45 | { |
46 | float lat_m; |
47 | int pixel_y; |
48 | |
49 | lat_m = atanh(sin(lat)); |
50 | |
51 | /* the formula is |
52 | * |
53 | * pixel_y = -(2^zoom * TILESIZE * lat_m) / 2PI + (2^zoom * TILESIZE) / 2 |
54 | */ |
55 | pixel_y = -(int)( (lat_m * TILESIZE * (1 << zoom) ) / (2*M_PI)) + |
56 | ((1 << zoom) * (TILESIZE/2) ); |
57 | |
58 | |
59 | return pixel_y; |
60 | } |
61 | |
62 | |
63 | int |
64 | lon2pixel( int zoom, |
65 | float lon) |
66 | { |
67 | int pixel_x; |
68 | int zoom_p = (1<<zoom) * TILESIZE/2; |
69 | |
70 | /* the formula is |
71 | * |
72 | * pixel_x = (2^zoom * TILESIZE * lon) / 2PI + (2^zoom * TILESIZE) / 2 |
73 | */ |
74 | pixel_x = (int)(lon * (zoom_p / M_PI)) + zoom_p; |
75 | |
76 | return pixel_x; |
77 | } |
78 | |
79 | float |
80 | pixel2lon( int zoom, |
81 | int pixel_x) |
82 | { |
83 | float lon; |
84 | int zoom_p = (1<<zoom) * TILESIZE/2; |
85 | |
86 | lon = (pixel_x - zoom_p) / (zoom_p / M_PI) ; |
87 | |
88 | return lon; |
89 | } |
90 | |
91 | float |
92 | pixel2lat( int zoom, |
93 | int pixel_y) |
94 | { |
95 | float lat, lat_m; |
96 | |
97 | lat_m = (-( pixel_y - ( (1<<zoom) * (TILESIZE/2) ) ) * (2*M_PI)) / |
98 | (TILESIZE * (1<<zoom)); |
99 | |
100 | lat = asin(tanh(lat_m)); |
101 | |
102 | return lat; |
103 | } |