Accessibility: mon_movement

Adds a new boolean option, mon_movement. When hero notices monster
movement, give a message. Use with spot_monsters and accessiblemsg.

doc/Guidebook.mn

@@ -4179,6 +4179,8 @@ Default \(oq}\(cq.
 ." Format menu entries using TAB to separate columns (default off).
 ." Only applicable to some menus, and only useful to some interfaces.
 ." Debug mode only.
+.lp mon_movement
+Show a message when hero notices a monster movement (default is off).
 .lp monpolycontrol
 Prompt for new form whenever any monster changes shape (default off).
 Debug mode only.
@@ -5947,6 +5949,9 @@ Prevent walking into water or lava.
 Adds direction or location information to messages.
 .lp spot_monsters
 Shows a message when hero notices a monster; combine with accessiblemsg.
+.lp mon_movement
+Shows a message when hero notices a monster movement;
+combine with spot_monsters and accessiblemsg.
 .lp autodescribe
 Automatically describe the terrain under the cursor when targeting.
 .lp mention_walls

doc/Guidebook.tex

@@ -4572,6 +4572,9 @@ Default `{\tt \verb+}+}'.
 % Only applicable to some menus, and only useful to some interfaces.
 % Debug mode only.
 %.lp
+\item[\ib{mon\verb+_+movement}]
+Show a message when hero notices a monster movement (default is off).
+%.lp
 \item[\ib{monpolycontrol}]
 Prompt for new form whenever any monster changes shape (default off).
 Debug mode only.
@@ -6546,6 +6549,10 @@ Adds direction or location information to messages.
 \item[\ib{spot\verb+_+monsters}]
 Shows a message when hero notices a monster; combine with accessiblemsg.
 %.lp
+\item[\ib{mon\verb+_+movement}]
+Shows a message when hero notices a monster movement;
+combine with spot\verb+_+monsters and accessiblemsg.
+%.lp
 \item[\ib{autodescribe}]
 Automatically describe the terrain under the cursor when targeting.
 %.lp

doc/fixes3-7-0.txt

@@ -2470,8 +2470,9 @@ allow the ')', '[', '(', '=', '"', and '*' commands to be preceded by the 'm'
 hot ground (Gehennom / Plane of Fire) often destroys dropped potions
 erinyes overhaul; they now attempt to punish heroes who have violated their
 	alignment and get stronger with greater alignment abuse
-accessibility options to tell where on map a message happened (accessiblemsg)
-	and to notify when a monster is spotted (spot_monsters)
+accessibility options to tell where on map a message happened (accessiblemsg),
+	to notify when a monster is spotted (spot_monsters), and when
+	a monster moved (mon_movement)
 
 
 Platform- and/or Interface-Specific New Features

include/flag.h

@@ -193,6 +193,7 @@ struct accessibility_data {
     coord msg_loc;         /* accessiblemsg: location */
     boolean mon_notices;   /* msg when hero notices a monster */
     int mon_notices_blocked; /* temp disable mon_notices */
+    boolean mon_movement;  /* msg when hero sees monster move */
 };
 
 /* Use notice_mon_off() / notice_mon_on() to temporarily disable

include/optlist.h

@@ -460,6 +460,9 @@ static int optfn_##a(int, int, boolean, char *, char *);
     NHOPTO("message types", Advanced, o_message_types, BUFSZ,
                 opt_in, set_in_game,
                 No, Yes, No, NoAlias, "edit message types")
+    NHOPTB(mon_movement, Advanced, 0, opt_in, set_in_game,
+           Off, Yes, No, No, NoAlias, &a11y.mon_movement, Term_False,
+           "message when hero sees monster movement")
     NHOPTB(monpolycontrol, Advanced, 0, opt_in, set_wizonly,
            Off, Yes, No, No, NoAlias, &iflags.mon_polycontrol, Term_False,
            "control monster polymorphs")

src/monmove.c

@@ -7,6 +7,7 @@
 #include "mfndpos.h"
 #include "artifact.h"
 
+static void msg_mon_movement(struct monst *, coordxy, coordxy) NONNULLARG1;
 static void watch_on_duty(struct monst *);
 static int disturb(struct monst *);
 static void release_hero(struct monst *);
@@ -26,6 +27,25 @@ static boolean m_balks_at_approaching(struct monst *);
 static boolean stuff_prevents_passage(struct monst *);
 static int vamp_shift(struct monst *, struct permonst *, boolean);
 
+/* a11y: give a message when monster moved */
+static void
+msg_mon_movement(struct monst *mtmp, coordxy omx, coordxy omy)
+{
+    if (a11y.mon_movement && canspotmon(mtmp) && mtmp->mspotted) {
+        coordxy nix = mtmp->mx, niy = mtmp->my;
+        boolean n2u = next2u(nix, niy),
+            close = !n2u && (distu(nix, niy) <= (BOLT_LIM * BOLT_LIM)),
+            closer = !n2u && (distu(nix, niy) <= distu(omx, omy));
+
+        pline_xy(nix, niy, "%s %s%s.", Monnam(mtmp),
+                 vtense((char *) 0, locomotion(mtmp->data, "move")),
+                 n2u ? " next to you"
+                 : (close && closer) ? " closer"
+                 : (close && !closer) ? " further away"
+                 : " in the distance");
+    }
+}
+
 /* monster has triggered trapped door lock or was present when it got
    triggered remotely (at door spot, door hit by zap);
    returns True if mtmp dies */
@@ -1870,6 +1890,7 @@ m_move(register struct monst *mtmp, int after)
            place_monster() only manipulate the head; they leave tail as-is */
         remove_monster(omx, omy);
         place_monster(mtmp, nix, niy);
+        msg_mon_movement(mtmp, omx, omy);
         /* for a long worm, insert a new segment to reconnect the head
            with the tail; worm_move() keeps the end of the tail if worm
            is scheduled to grow, removes that for move-without-growing */