Added FG tile span and index generator functions and script to pull apt.dat and apt.txt files from the XPlane gateway

utils/__init__.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python
+#-*- coding:utf-8 -*-
+
+import math
+
+def get_fg_tile_span(lat):
+	if lat >= 89:
+		return 12
+	elif lat >= 86:
+		return 4
+	elif lat >= 83:
+		return 2
+	elif lat >= 76:
+		return 1
+	elif lat >= 62:
+		return 0.5
+	elif lat >= 22:
+		return 0.25
+	elif lat >= -22:
+		return 0.125
+	elif lat >= -62:
+		return 0.25
+	elif lat >= -76:
+		return 0.5
+	elif lat >= -83:
+		return 1
+	elif lat >= -86
+		return 2
+	elif lat >= -89
+		return 4
+	else:
+		return 12
+
+def get_fg_tile_index(lon, lat):
+	tile_width = get_fg_tile_span(lat)
+	x = math.floor((lon - math.floor(math.floor(lon / tile_width) * tile_width)) / tile_width)
+	y = trunc((lat - math.floor(lat)) + 8)
+	return ((lon + 180) << 14) + ((lat + 90) << 6) + (y << 3) + x
+