# python code to generate kml snapshots of a spreading plume 

import random
import math

centlon = -157.942858
centlat =   21.333217

 
ident = 1
day = 12
month = 12
year = 2012
minute = 0
starthour = 0
endhour  = 24 
spreadrate = 5.0 * 0.01666     # decimal degrees / hr
windxrate = 15.0 * 0.01666 * -1.0  
windyrate =  5.0 * 0.01666 * -1.0 

# print kml header stuff...
print "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"
print "<kml xmlns=\"http://www.opengis.net/kml/2.2\">"


for hour in range(starthour, endhour):
  # update center  
  centlon += windxrate * random.random()    
  centlat += windyrate * random.random()


# print kml to start one placemark
# using the name field to associate a time as:  dd/mm/yyyy hh:mm 
# and inidicating that we have a polygon with coordinates listed

  print "  <Placemark>"
  print "    <name>%02d/%02d/%4d %02d:%02d</name>" % (day, month, year, hour, minute)  
  print "    <Polygon>"
  print "       <coordinates>"

# adjust the radius and loop around the compass computing points
# and printing them (not sure that the explicit closure by repeating
# the first point is required)

  radius = hour * spreadrate  
  for radial in range (0, 360, 10):
    radi = radius + ((random.random() * 0.2) - 0.1)
    lon = centlon + radi * math.cos(math.radians(radial)) 
    lat = centlat + radi * math.sin(math.radians(radial))  
    if radial==0:
       flon = lon
       flat = lat
    print "        %lf,%lf,0" % (lon, lat)
  print "        %lf,%lf,0" % (flon, flat)

# finish each coordinate list, Polygon and Placemark

  print "       </coordinates>"
  print "    </Polygon>"
  print "  </Placemark>"

# finish the kml
 
print "</kml>"