[Freeciv-Dev] (PR#6321) is_border_map_pos for iso-maps

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

is_border_map_pos doesn't work as-is for iso-maps.  The easiest way to 
"fix" it is just to always return TRUE for iso-maps.  This slows things 
down a bit (for iso-maps only), but that's okay.

Giving a correct implementation is a bit uglier (remember native 
coordinates are compressed 2x in the X direction).  Something like

   (topo_has_flag(TF_ISO)
    ? (map_to_native_x(x, y) < 2 * dist
       || map_to_native_x(x, y) >= map.xsize - 2 * dist
       || map_to_native_y(x, y) < dist
       || map_to_native_y(x, y) >= map.ysize - dist)
    : (...))

which may not be faster at all, depending on optimizations.  This can 
wait until later.  Perhaps it would be written simpler as

   #define X_FACTOR (topo_has_flag(TF_ISO) ? 2 : 1)
   #define Y_FACTOR 1

   #define IS_BORDER_MAP_POS(x, y)
     (map_to_native_x(x, y) < X_FACTOR * dist
      || map_to_native_x(x, y) >= map.xsize - X_FACTOR * dist
      || map_to_native_y(x, y) < Y_FACTOR * dist
      || map_to_native_y(x, y) >= map.ysize - Y_FACTOR * dist)

Either way, it can wait until later.

jason

Index: common/map.h
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/map.h,v
retrieving revision 1.154
diff -u -r1.154 map.h
--- common/map.h        2003/09/23 19:47:22     1.154
+++ common/map.h        2003/09/29 13:48:26
@@ -309,9 +309,12 @@
  * A "border position" is any one that _may have_ positions within
  * map distance dist that are non-normal.  To see its correctness,
  * consider the case where dist is 1 or 0.
+ *
+ * TODO: implement this for iso-maps.
  */
 #define IS_BORDER_MAP_POS(x, y, dist)                         \
-  ((x) < (dist) || (x) >= map.xsize - (dist)                  \
+  (topo_has_flag(TF_ISO)                                      \
+   || (x) < (dist) || (x) >= map.xsize - (dist)               \
    || (y) < (dist) || (y) >= map.ysize - (dist))
 
 bool normalize_map_pos(int *x, int *y);