altos-mapd: Check nearest portion of tile to launch site
authorKeith Packard <keithp@keithp.com>
Sun, 7 Oct 2018 20:08:30 +0000 (14:08 -0600)
committerKeith Packard <keithp@keithp.com>
Sun, 7 Oct 2018 20:08:30 +0000 (14:08 -0600)
We limit tile queries to those within 17km of a known launch
site. Change the check to look at the portion of the tile nearest each
launch site, instead of only checking the center location of the tile.

Signed-off-by: Keith Packard <keithp@keithp.com>
map-server/altos-mapd/AltosMapd.java
map-server/altos-mapd/AltosMapdClient.java

index b410586..1be1655 100644 (file)
@@ -57,7 +57,23 @@ public class AltosMapd implements AltosLaunchSiteListener {
                }
        }
 
-       public static boolean check_lat_lon(double lat, double lon) {
+       private static boolean west_of(double a, double b) {
+               double  diff = b - a;
+
+               while (diff >= 360.0)
+                       diff -= 360.0;
+               while (diff <= -360.0)
+                       diff += 360.0;
+
+               return diff >= 0;
+       }
+
+       public static boolean check_lat_lon(double lat, double lon, int zoom) {
+               AltosMapTransform       transform = new AltosMapTransform(px_size, px_size, zoom, new AltosLatLon(lat, lon));
+
+               AltosLatLon             upper_left = transform.screen_lat_lon(new AltosPointInt(0, 0));
+               AltosLatLon             lower_right = transform.screen_lat_lon(new AltosPointInt(px_size, px_size));
+
                synchronized (launch_sites_ready) {
                        if (launch_sites == null) {
                                try {
@@ -73,8 +89,34 @@ public class AltosMapd implements AltosLaunchSiteListener {
                }
 
                for (AltosLaunchSite site : launch_sites) {
+
+                       /* Figure out which point in the tile to
+                        * measure to the site That's one of the edges
+                        * or the site location depend on where the
+                        * site is in relation to the tile
+                        */
+
+                       double          check_lon;
+
+                       if (west_of(site.longitude, upper_left.lon))
+                               check_lon = upper_left.lon;
+                       else if (west_of(lower_right.lon, site.longitude))
+                               check_lon = lower_right.lon;
+                       else
+                               check_lon = site.longitude;
+
+                       double          check_lat;
+
+                       if (site.latitude < lower_right.lat)
+                               check_lat = lower_right.lat;
+                       else if (upper_left.lat < site.latitude)
+                               check_lat = upper_left.lat;
+                       else
+                               check_lat = site.latitude;
+
                        AltosGreatCircle gc = new AltosGreatCircle(site.latitude, site.longitude,
-                                                                  lat, lon);
+                                                                  check_lat, check_lon);
+
                        if (gc.distance <= valid_radius)
                                return true;
                }
index 1917408..6c95da8 100644 (file)
@@ -85,7 +85,7 @@ public class AltosMapdClient extends Thread implements AltosMapStoreListener {
                                    addr == null)
                                {
                                        set_status(400);
-                               } else if (!AltosMapd.check_lat_lon(lat, lon)) {
+                               } else if (!AltosMapd.check_lat_lon(lat, lon, zoom)) {
                                        set_status(403);        /* Forbidden */
                                } else {