endgame portal detection (trunk only)

In the newsgroup about three weeks ago someone described trying to
use the Bell of Opening to find the magic portal on the Plane of Water
and not succeeding.  It's supposed to work like a wand of secret door
detection to mark nearby traps as known.  And does, but it turns out
that the wand wasn't working as expected there either.  They both require
line of sight, and since the water outside of the bubbles blocks that
they only found the portal if it was within the same bubble as the hero.
(Clouds on the Plane of Air posed a similar problem, although monster
activity usually reveals the portal on that level so this wasn't much of
an issue there.)  Since the detection magic doesn't require the hero to
see the traps--wand and Bell both work while blind--this patch overrides
the line of sight requirement on the Planes of Water and Air.  As long as
hero is within the detection magic's range, the portals on those levels
will get marked as having been seen and when the hero gets into the right
bubble or out of the clouds the portal traps will be shown on the map.

     The line-of-sight override code is simple-minded and lets players
find traps through boulders when/if those are present (but the found
traps won't be seen yet since vision still controls the map display).
Also, it assumes that only water/air/cloud terrain is present so could
potentially yield strange results if any other terrain gets introduced on
either of those two levels.

doc/fixes35.0

@@ -271,6 +271,8 @@ it was possible to generate an object of 0 gold pieces by dropping 2**32 gold
 wizard mode's sanity_check option missed nested containers and migrating mons
 always update map display and use up turn if open or close command attempted
 	while blind reveals change in door state or discloses non-door spot
+secret door detection's trap finding is no longer blocked by water or clouds
+	on the Planes of Water and Air
 
 
 Platform- and/or Interface-Specific Fixes

include/extern.h

@@ -252,6 +252,7 @@ E void FDECL(openone, (int,int,genericptr_t));
 #endif
 E int NDECL(findit);
 E int NDECL(openit);
+E boolean FDECL(detecting, (void (*)(int,int,genericptr)));
 E void FDECL(find_trap, (struct trap *));
 E int FDECL(dosearch0, (int));
 E int NDECL(dosearch);

src/detect.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)detect.c	3.5	2006/05/13	*/
+/*	SCCS Id: @(#)detect.c	3.5	2007/11/05	*/
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -1194,6 +1194,14 @@ openit()	/* returns number of things found and opened */
 	return(num);
 }
 
+/* callback hack for overriding vision in do_clear_area() */
+boolean
+detecting(func)
+    void FDECL((*func), (int,int,genericptr_t));
+{
+    return (func == findone || func == openone);
+}
+
 void
 find_trap(trap)
 struct trap *trap;

src/vision.c

@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)vision.c	3.5	2007/05/11	*/
+/*	SCCS Id: @(#)vision.c	3.5	2007/11/05	*/
 /* Copyright (c) Dean Luick, with acknowledgements to Dave Cohrs, 1990.	*/
 /* NetHack may be freely redistributed.  See license for details.	*/
 
@@ -2606,6 +2606,12 @@ do_clear_area(scol,srow,range,func,arg)
 	    register int x;
 	    int y, min_x, max_x, max_y, offset;
 	    char *limits;
+	    boolean override_vision;
+
+	    /* vision doesn't pass through water or clouds, detection should
+	       [this probably ought to be an arg supplied by our caller...] */
+	    override_vision = (Is_waterlevel(&u.uz) || Is_airlevel(&u.uz)) &&
+			      detecting(func);
 
 	    if (range > MAX_RADIUS || range < 1)
 		panic("do_clear_area:  illegal range %d", range);
@@ -2619,7 +2625,7 @@ do_clear_area(scol,srow,range,func,arg)
 		if((min_x = (scol - offset)) < 0) min_x = 0;
 		if((max_x = (scol + offset)) >= COLNO) max_x = COLNO-1;
 		for (x = min_x; x <= max_x; x++)
-		    if (couldsee(x, y))
+		    if (couldsee(x, y) || override_vision)
 			(*func)(x, y, arg);
 	    }
 	}