[Freeciv-Dev] (PR#4586) vector wrapping in do_move_unit

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

The code in do_move_unit to determine the vector of movement of a unit 
is not topology-safe.  Using map_distance_vector can make it so.

jason

Index: client/control.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/client/control.c,v
retrieving revision 1.103
diff -u -r1.103 control.c
--- client/control.c    2003/07/10 03:50:55     1.103
+++ client/control.c    2003/07/17 04:22:12
@@ -1248,12 +1248,11 @@
     center_tile_mapcanvas(pinfo->x, pinfo->y);
 
   if(!pinfo->carried && !was_teleported) {
-    int dx=pinfo->x - x;
-    if(dx>1) dx=-1;
-    else if(dx<-1)
-      dx=1;
+    int dx, dy;
+
+    map_distance_vector(&dx, &dy, punit->x, punit->y, pinfo->x, pinfo->y);
     if(smooth_move_units)
-      move_unit_map_canvas(punit, x, y, dx, pinfo->y - punit->y);
+      move_unit_map_canvas(punit, x, y, dx, dy);
     refresh_tile_mapcanvas(x, y, FALSE);
   }