#!/usr/bin/env ruby
### wxWindCompass --- Generate data for a wind compass graph.
## Copyright 2006 by Dave Pearson <davep@davep.org>
## $Revision: 1.1 $
##
## wxWindCompass is free software distributed under the terms of the GNU
## General Public Licence, version 2. For details see the file COPYING.

# If we've been passsed the line count.
if ARGV[ 0 ] then

  # Get the line count.
  linecount = ARGV[ 0 ].to_f

  # Line counter.
  n = 0

  # For each line.
  $stdin.each do |line|

    # Split the data
    data = line.chomp.split( " " )

    # Extract the speed and direction.
    speed     = data[ 0 ].to_f
    direction = data[ 1 ].to_f

    # If there was wind.
    if speed > 0 then

      # Figure out where to plot.
      x = ( direction / 360.0 ) * ( Math::PI * 2 )
      y = n / linecount

      # Emit the line.
      puts "#{ Math.sin( x ) * y }, #{ Math.cos( x ) * y }"

    end
      
    # Increment the line counter.
    n += 1

  end
  
else
  puts "Syntax:"
  puts "  wxWindCompass <line-count>"
end