Accessibility: Show a message when monster is spotted

Adds a new boolean option, spot_monsters.  If on, every time
the hero notices a monster which was out of sight before,
a message is given.  Combine with accessiblemsg to get the
monster location:

(3north): You see a newt.

Breaks saves and bones.

doc/Guidebook.mn

@@ -4650,6 +4650,8 @@ Allow sounds to be emitted from an integrated sound library (default on).
 Display a sparkly effect when a monster (including yourself) is hit by an
 attack to which it is resistant (default on).
 Persistent.
+.lp spot_monsters
+Show a message when hero notices a monster (default is off).
 .lp standout
 Boldface monsters and \(lq\fB\-\-More\-\-\fP\(rq (default off).
 Persistent.
@@ -5938,6 +5940,8 @@ Rogue-like commands.
 Prevent walking into water or lava.
 .lp accessiblemsg
 Adds direction or location information to messages.
+.lp spot_monsters
+Shows a message when hero notices a monster; combine with accessiblemsg.
 .lp autodescribe
 Automatically describe the terrain under the cursor when targeting.
 .lp mention_walls

doc/Guidebook.tex

@@ -5092,6 +5092,9 @@ Allow sounds to be emitted from an integrated sound library (default on).
 Display a sparkly effect when a monster (including yourself) is hit by an
 attack to which it is resistant (default on).  Persistent.
 %.lp
+\item[\ib{spot\verb+_+monsters}]
+Show a message when hero notices a monster (default is off).
+%.lp
 \item[\ib{standout}]
 Boldface monsters and ``{\tt --More--}'' (default off).  Persistent.
 %.lp
@@ -6535,6 +6538,9 @@ Prevent walking into water or lava.
 \item[\ib{accessiblemsg}]
 Adds direction or location information to messages.
 %.lp
+\item[\ib{spot\verb+_+monsters}]
+Shows a message when hero notices a monster; combine with accessiblemsg.
+%.lp
 \item[\ib{autodescribe}]
 Automatically describe the terrain under the cursor when targeting.
 %.lp

include/extern.h

@@ -1074,6 +1074,8 @@ extern boolean test_move(coordxy, coordxy, coordxy, coordxy, int);
 extern int wiz_debug_cmd_traveldisplay(void);
 #endif
 extern boolean u_rooted(void);
+extern void notice_mon(struct monst *) NONNULLARG1;
+extern void notice_all_mons(boolean);
 extern void impact_disturbs_zombies(struct obj *, boolean) NONNULLARG1;
 extern void disturb_buried_zombies(coordxy, coordxy);
 extern boolean u_maybe_impaired(void);

include/flag.h

@@ -191,8 +191,20 @@ struct debug_flags {
 struct accessibility_data {
     boolean accessiblemsg; /* use msg_loc for plined messages */
     coord msg_loc;         /* accessiblemsg: location */
+    boolean mon_notices;   /* msg when hero notices a monster */
+    int mon_notices_blocked; /* temp disable mon_notices */
 };
 
+/* Use notice_mon_off() / notice_mon_on() to temporarily disable
+   noticing the monsters in the vision code - perhaps the game
+   needs to output some other messages in between.
+   Call notice_all_mons() afterwards to catch up. */
+#define notice_mon_off() do { a11y.mon_notices_blocked++; } while(0)
+#define notice_mon_on()  do { if (--a11y.mon_notices_blocked < 0) { \
+            impossible("mon_notices_blocked<0");                    \
+            a11y.mon_notices_blocked = 0;                           \
+        } } while(0)
+
 /*
  * Stuff that really isn't option or platform related and does not
  * get saved and restored.  They are set and cleared during the game

include/monst.h

@@ -160,6 +160,8 @@ struct monst {
     Bitfield(mtemplit, 1);  /* temporarily seen; only valid during bhit() */
     Bitfield(meverseen, 1); /* mon has been seen at some point */
 
+    Bitfield(mspotted, 1);  /* mon is currently seen by hero */
+
 #define MAX_NUM_WORMS 32    /* should be 2^(wormno bitfield size) */
 
     unsigned long mstrategy; /* for monsters with mflag3: current strategy */

include/optlist.h

@@ -654,6 +654,9 @@ static int optfn_##a(int, int, boolean, char *, char *);
     NHOPTB(sparkle, Map, 0, opt_out, set_in_game,
            On, Yes, No, No, NoAlias, &flags.sparkle, Term_False,
            "display sparkly effect when resisting magic")
+    NHOPTB(spot_monsters, Advanced, 0, opt_in, set_in_game,
+           Off, Yes, No, No, NoAlias, &a11y.mon_notices, Term_False,
+           "message when hero spots a monster")
     NHOPTB(splash_screen, Advanced, 0, opt_out, set_in_config,
            On, Yes, No, No, NoAlias, &iflags.wc_splash_screen, Term_False,
            (char *)0)

include/patchlevel.h

@@ -17,7 +17,7 @@
  * Incrementing EDITLEVEL can be used to force invalidation of old bones
  * and save files.
  */
-#define EDITLEVEL 96
+#define EDITLEVEL 97
 
 /*
  * Development status possibilities.

src/allmain.c

@@ -705,6 +705,8 @@ newgame(void)
 {
     int i;
 
+    /* make sure welcome messages are given before noticing monsters */
+    notice_mon_off();
     disp.botlx = TRUE;
     gc.context.ident = 1;
     gc.context.warnlevel = 1;
@@ -765,6 +767,8 @@ newgame(void)
 
     /* Success! */
     welcome(TRUE);
+    notice_mon_on(); /* now we can notice monsters */
+    notice_all_mons(TRUE);
     return;
 }
 

src/do.c

@@ -1807,6 +1807,7 @@ goto_level(
     /* Reset the screen. */
     vision_reset(); /* reset the blockages */
     reset_glyphmap(gm_levelchange);
+    notice_mon_off(); /* not noticing monsters yet! */
     docrt(); /* does a full vision recalc */
     flush_screen(-1);
 
@@ -1923,6 +1924,8 @@ goto_level(
 #ifdef INSURANCE
     save_currentstate();
 #endif
+    notice_mon_on();
+    notice_all_mons(TRUE);
 
     print_level_annotation();
     /* give room entrance message, if any */

src/hack.c

@@ -12,6 +12,7 @@ static int moverock(void);
 static void dosinkfall(void);
 static boolean findtravelpath(int);
 static boolean trapmove(coordxy, coordxy, struct trap *);
+static int QSORTCALLBACK notice_mons_cmp(const genericptr, const genericptr);
 static schar u_simple_floortyp(coordxy, coordxy);
 static boolean swim_move_danger(coordxy, coordxy);
 static boolean domove_bump_mon(struct monst *, int) NONNULLARG1;
@@ -1601,6 +1602,80 @@ u_rooted(void)
     return FALSE;
 }
 
+void
+notice_mon(struct monst *mtmp)
+{
+    if (a11y.mon_notices && !a11y.mon_notices_blocked) {
+        boolean spot = canspotmon(mtmp)
+            && !(is_hider(mtmp->data)
+                 && (mtmp->mundetected
+                     || M_AP_TYPE(mtmp) == M_AP_FURNITURE
+                     || M_AP_TYPE(mtmp) == M_AP_OBJECT));
+
+        if (spot && !mtmp->mspotted && !DEADMONSTER(mtmp)) {
+            mtmp->mspotted = TRUE;
+            set_msg_xy(mtmp->mx, mtmp->my);
+            You("%s %s.", canseemon(mtmp) ? "see" : "notice",
+                x_monnam(mtmp,
+                     mtmp->mtame ? ARTICLE_YOUR
+                     : (!has_mgivenname(mtmp)
+                        && !type_is_pname(mtmp->data)) ? ARTICLE_A
+                     : ARTICLE_NONE,
+                     (mtmp->mpeaceful && !mtmp->mtame) ? "peaceful" : 0,
+                     has_mgivenname(mtmp) ? SUPPRESS_SADDLE : 0, FALSE));
+        } else if (!spot) {
+            mtmp->mspotted = FALSE;
+        }
+    }
+}
+
+static int QSORTCALLBACK
+notice_mons_cmp(const genericptr ptr1, const genericptr ptr2)
+{
+    const struct monst *m1 = *(const struct monst **) ptr1,
+        *m2 = *(const struct monst **) ptr2;
+
+    return (distu(m1->mx, m1->my) - distu(m2->mx, m2->my));
+}
+
+void
+notice_all_mons(boolean reset)
+{
+    if (a11y.mon_notices && !a11y.mon_notices_blocked) {
+        struct monst *mtmp;
+        struct monst **arr = NULL;
+        int i = 0, cnt = 0;
+
+        for (mtmp = fmon; mtmp; mtmp = mtmp->nmon)
+            if (canspotmon(mtmp))
+                cnt++;
+            else if (reset)
+                mtmp->mspotted = FALSE;
+
+        if (!cnt)
+            return;
+
+        arr = (struct monst **) alloc(cnt * sizeof(struct monst *));
+
+
+        for (mtmp = fmon; mtmp; mtmp = mtmp->nmon) {
+            if (!canspotmon(mtmp))
+                mtmp->mspotted = FALSE;
+            else if (!DEADMONSTER(mtmp) && i < cnt)
+                arr[i++] = mtmp;
+        }
+
+        if (i) {
+            qsort((genericptr_t) arr, (size_t) i, sizeof *arr, notice_mons_cmp);
+
+            for (i = 0; i < cnt; i++)
+                notice_mon(arr[i]);
+        }
+
+        free(arr);
+    }
+}
+
 /* maybe disturb buried zombies when an object is dropped or thrown nearby */
 void
 impact_disturbs_zombies(struct obj *obj, boolean violent)

src/monmove.c

@@ -1307,6 +1307,8 @@ postmov(
     boolean canseeit = cansee(mtmp->mx, mtmp->my),
             didseeit = canseeit;
 
+    notice_mon(mtmp);
+
     if (mmoved == MMOVE_MOVED) {
         nix = mtmp->mx, niy = mtmp->my;
         /* sequencing issue:  when monster movement decides that a

src/teleport.c

@@ -513,6 +513,7 @@ teleds(coordxy nux, coordxy nuy, int teleds_flags)
     see_monsters();
     gv.vision_full_recalc = 1;
     nomul(0);
+    notice_mon_off();
     vision_recalc(0); /* vision before effects */
 
     /* this used to take place sooner, but if a --More-- prompt was issued
@@ -542,6 +543,8 @@ teleds(coordxy nux, coordxy nuy, int teleds_flags)
     /* possible shop entry message comes after guard's shrill whistle */
     spoteffects(TRUE);
     invocation_message();
+    notice_mon_on();
+    notice_all_mons(TRUE);
     return;
 }
 

src/vision.c

@@ -837,6 +837,8 @@ vision_recalc(int control)
     /* Set the new min and max pointers. */
     gv.viz_rmin = next_rmin;
     gv.viz_rmax = next_rmax;
+
+    notice_all_mons(TRUE);
 }
 
 /*