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Diffstat (limited to 'kworldwatch/sunclock.c')
| -rw-r--r-- | kworldwatch/sunclock.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/kworldwatch/sunclock.c b/kworldwatch/sunclock.c new file mode 100644 index 0000000..46058ac --- /dev/null +++ b/kworldwatch/sunclock.c @@ -0,0 +1,164 @@ +/* + * Sun clock. X11 version by John Mackin. + * + * This program was derived from, and is still in part identical with, the + * Suntools Sun clock program whose author's comment appears immediately + * below. Please preserve both notices. + * + * The X11R3/4 version of this program was written by John Mackin, at the + * Basser Department of Computer Science, University of Sydney, Sydney, + * New South Wales, Australia; <john@cs.su.oz.AU>. This program, like + * the one it was derived from, is in the public domain: `Love is the + * law, love under will.' + */ + +/* + + Sun clock + + Designed and implemented by John Walker in November of 1988. + + Version for the Sun Workstation. + + The algorithm used to calculate the position of the Sun is given in + Chapter 18 of: + + "Astronomical Formulae for Calculators" by Jean Meeus, Third Edition, + Richmond: Willmann-Bell, 1985. This book can be obtained from: + + Willmann-Bell + P.O. Box 35025 + Richmond, VA 23235 + USA + Phone: (804) 320-7016 + + This program was written by: + + John Walker + Autodesk, Inc. + 2320 Marinship Way + Sausalito, CA 94965 + USA + Fax: (415) 389-9418 + Voice: (415) 332-2344 Ext. 2829 + Usenet: {sun,well,uunet}!acad!kelvin + or: kelvin@acad.uu.net + + modified for interactive maps by + + Stephen Martin + Fujitsu Systems Business of Canada + smartin@fujitsu.ca + + This program is in the public domain: "Do what thou wilt shall be the + whole of the law". I'd appreciate receiving any bug fixes and/or + enhancements, which I'll incorporate in future versions of the + program. Please leave the original attribution information intact so + that credit and blame may be properly apportioned. + + Revision history: + + 1.0 12/21/89 Initial version. + 8/24/89 Finally got around to submitting. + + 1.1 8/31/94 Version with interactive map. + 1.2 10/12/94 Fixes for HP and Solaris, new icon bitmap + 1.3 11/01/94 Timezone now shown in icon + 1.4 03/29/98 Fixed city drawing, added icon animation + +*/ + +#include "sunclock.h" + +void projillum(short *wtab, int xdots, int ydots, double dec); + +/* PROJILLUM -- Project illuminated area on the map. */ + +void +projillum(wtab, xdots, ydots, dec) +short *wtab; +int xdots, ydots; +double dec; +{ + int i, ftf = 1, ilon, ilat, lilon = 0, lilat = 0, xt; + double m, x, y, z, th, lon, lat, s, c; + + /* Clear unoccupied cells in width table */ + + for (i = 0; i < ydots; i++) + wtab[i] = -1; + + /* Build transformation for declination */ + + s = sin(-dtr(dec)); + c = cos(-dtr(dec)); + + /* Increment over a semicircle of illumination */ + + for (th = -(PI / 2); th <= PI / 2 + 0.001; + th += PI / TERMINC) { + + /* Transform the point through the declination rotation. */ + + x = -s * sin(th); + y = cos(th); + z = c * sin(th); + + /* Transform the resulting co-ordinate through the + map projection to obtain screen co-ordinates. */ + + lon = (y == 0 && x == 0) ? 0.0 : rtd(atan2(y, x)); + lat = rtd(asin(z)); + + ilat = ydots - (lat + 90) * (ydots / 180.0); + ilon = lon * (xdots / 360.0); + + if (ftf) { + + /* First time. Just save start co-ordinate. */ + + lilon = ilon; + lilat = ilat; + ftf = 0; + } else { + + /* Trace out the line and set the width table. */ + + if (lilat == ilat) { + wtab[(ydots - 1) - ilat] = ilon == 0 ? 1 : ilon; + } else { + m = ((double) (ilon - lilon)) / (ilat - lilat); + for (i = lilat; i != ilat; i += sgn(ilat - lilat)) { + xt = lilon + floor((m * (i - lilat)) + 0.5); + wtab[(ydots - 1) - i] = xt == 0 ? 1 : xt; + } + } + lilon = ilon; + lilat = ilat; + } + } + + /* Now tweak the widths to generate full illumination for + the correct pole. */ + + if (dec < 0.0) { + ilat = ydots - 1; + lilat = -1; + } else { + ilat = 0; + lilat = 1; + } + + for (i = ilat; i != ydots / 2; i += lilat) { + if (wtab[i] != -1) { + while (1) { + wtab[i] = xdots / 2; + if (i == ilat) + break; + i -= lilat; + } + break; + } + } +} + |