prototype of lunar

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 65 insertions, 0 deletions

diff --git a/src/plugins/lunar.py b/src/plugins/lunar.py
new file mode 100644
index 0000000..2df7c0c
--- /dev/null
+++ b/src/plugins/lunar.py
@@ -0,0 +1,65 @@
+# -*- python -*-
+'''
+xpybar – xmobar replacement written in python
+Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+'''
+
+import math
+import time
+
+
+def julian_day(t):
+    '''
+    Converts a POSIX time timestamp to a Julian Day timestamp
+    
+    @param   t:float  The time in POSIX time
+    @return  :float   The time in Julian Days
+    '''
+    return t / 86400.0 + 2440587.5
+
+def radians(deg):
+    '''
+    Convert an angle from degrees to radians
+    
+    @param   deg:float  The angle in degrees
+    @return  :float     The angle in radians
+    '''
+    return deg * math.pi / 180
+
+ref = julian_day(934329600) # 11 August 1999 00:00:00 UTC
+now = julian_day(time.time())
+synodic_month = 29.530588853
+
+fraction = ((now - ref) / synodic_month) % 1
+waxing = fraction <= 0.5 # we get an off by one without equality
+print('fraction: %f' % fraction)
+print('waxing' if waxing else 'waning')
+
+terminator = 90 - 360 * fraction # sunlit trailing
+if terminator < -90:
+    terminator += 180 # visible side
+print('terminator: %f°' % terminator)
+
+hacoversin = lambda deg : 0.5 - math.sin(radians(deg)) / 2
+
+inverted = terminator < 0
+illumination = hacoversin(abs(terminator))
+
+if (not waxing) != inverted:
+    illumination = 1 - illumination
+
+print('illumination: %.2f%%' % (illumination * 100))
+