AltosSiteMap: explain tile size better

diff --git a/ao-tools/altosui/AltosSiteMap.java b/ao-tools/altosui/AltosSiteMap.java
index 72a65b1529721d57f389c01b70914bcfb73319a1..e222e2c8cc88e592a8f90627d24c2986a33b54b8 100644 (file)
--- a/ao-tools/altosui/AltosSiteMap.java
+++ b/ao-tools/altosui/AltosSiteMap.java
@@ -33,8 +33,10 @@ import java.awt.geom.Point2D;
 import java.awt.geom.Line2D;
 
 public class AltosSiteMap extends JScrollPane implements AltosFlightDisplay {
-       // max vertical step in a tile in naut. miles
-       static final double tile_size_nmi = 2.0;
+       // preferred vertical step in a tile in naut. miles
+       // will actually choose a step size between x and 2x, where this
+       // is 1.5x
+       static final double tile_size_nmi = 1.5;
 
        static final int px_size = 512;
 
@@ -117,7 +119,7 @@ public class AltosSiteMap extends JScrollPane implements AltosFlightDisplay {
                        scale_x = 256/360.0 * Math.pow(2, zoom);
                        scale_y = 256/(2.0*Math.PI) * Math.pow(2, zoom);
                        locn = pt(lat, lng);
-                       north_step = pt(lat+tile_size_nmi/60.0, lng);
+                       north_step = pt(lat+tile_size_nmi*4/3/60.0, lng);
                        if (locn.y - north_step.y > px_size)
                                break;
                } while (zoom < 22);