# poly2area.ak
# Program Name : poly2area.ak
# Author       : Eric Keyser
# November 23, 2004

# This script will take a Photon ascii file and compute comma separated areas.
# Area is in km2 and acres


BEGIN {

Layer = "UNKNOWN"
Colour = "Black"


# Outer loop
     while ( getline == 1 ) {
       if ($1 == "CultureLayer" ) {
        split ( $2, name, "\"")
        Layer = name[2]
#        printf ("Layer %s \n", Layer) 
       }
       if ($1 == "Polyline" ) {
        split ( $2, name, "\"")
        Colour = name[2]
#        printf ("Layer=%s Colour=%s\n", Layer, Colour) 
        getline
        numlines = $1
#        printf"Numlines = %d\n", numlines

        for (i=1; i <= numlines; i++) {
         getline
         X[i] = $1
         Y[i] = $2
        }
        area = 0
        for (i=2; i <= numlines; i++) {
         
         area = area +  ((Y[i] + Y[i-1])/2 * (X[i] - X[i-1]) / 1E6)
#         printf ("%d %12.2f Area %12.2f %12.2f\n", i, temp, area, X[i])
        }
        if (area < 0) area = -1 * area
        printf ("%s,%s,%12.2f,%12.2f\n", Layer, Colour, area, 247.105*area) 
         
       }
  }
 }
#Middle
    {
}

END {  }