Unify mesmerisation code.

There were several places that had copies of the same code, checking
whether mesmerisation blocked movement to a given target.

The various mesmerisation functions have become methods of player
and were moved into behold.cc.

1 files changed, 173 insertions, 0 deletions

diff --git a/crawl-ref/source/behold.cc b/crawl-ref/source/behold.cc
new file mode 100644
index 0000000000..37571e1b0a
--- /dev/null
+++ b/crawl-ref/source/behold.cc
@@ -0,0 +1,173 @@
+#include "AppHdr.h"
+
+#include "player.h"
+
+#include "coord.h"
+#include "debug.h"
+#include "env.h"
+#include "los.h"
+#include "mon-util.h"
+#include "monster.h"
+#include "random.h"
+#include "stuff.h"
+#include "view.h"
+
+// Add a monster to the list of beholders.
+void player::add_beholder(const monsters* mon)
+{
+    if (!duration[DUR_MESMERISED])
+    {
+        duration[DUR_MESMERISED] = 7;
+        beholders.push_back(mon->mindex());
+        mprf(MSGCH_WARN, "You are mesmerised by %s!",
+                         mon->name(DESC_NOCAP_THE).c_str());
+    }
+    else
+    {
+        duration[DUR_MESMERISED] += 5;
+        if (!beheld_by(mon))
+            beholders.push_back(mon->mindex());
+    }
+
+    if (duration[DUR_MESMERISED] > 12)
+        duration[DUR_MESMERISED] = 12;
+}
+
+// Whether player is mesmerised.
+bool player::beheld() const
+{
+    ASSERT(duration[DUR_MESMERISED] > 0 == !beholders.empty());
+    return (duration[DUR_MESMERISED] > 0);
+}
+
+// Whether player is mesmerised by the given monster.
+bool player::beheld_by(const monsters* mon) const
+{
+    for (unsigned int i = 0; i < beholders.size(); i++)
+        if (beholders[i] == mon->mindex())
+            return (true);
+    return (false);
+}
+
+// Checks whether a beholder keeps you from moving to
+// target, and returns one if it exists.
+monsters* player::get_beholder(const coord_def &target) const
+{
+    for (unsigned int i = 0; i < beholders.size(); i++)
+    {
+        monsters *mon = &menv[beholders[i]];
+        const int olddist = grid_distance(you.pos(), mon->pos());
+        const int newdist = grid_distance(target, mon->pos());
+
+        if (olddist < newdist)
+            return (mon);
+    }
+    return (NULL);
+}
+
+monsters* player::get_any_beholder() const
+{
+    if (beholders.size() > 0)
+        return (&menv[beholders[0]]);
+    else
+        return (NULL);
+}
+
+// Removes a monster from the list of beholders if present.
+void player::remove_beholder(const monsters *mon)
+{
+    for (unsigned int i = 0; i < beholders.size(); i++)
+        if (beholders[i] == mon->mindex())
+        {
+            beholders.erase(beholders.begin() + i);
+            _removed_beholder();
+            return;
+        }
+}
+
+// Clear the list of beholders. Doesn't message.
+void player::clear_beholders()
+{
+    beholders.clear();
+    duration[DUR_MESMERISED] = 0;
+}
+
+// Possibly end mesmerisation if a loud noise happened.
+void player::beholders_check_noise(int loudness)
+{
+    if (loudness >= 20 && you.beheld())
+    {
+        mprf("For a moment, you cannot hear the mermaid%s!",
+             beholders.size() > 1 ? "s" : "");
+        clear_beholders();
+        _removed_beholder();
+    }
+}
+
+// Update all beholders' status after changes.
+void player::update_beholders()
+{
+    if (!beheld())
+        return;
+    bool removed = false;
+    for (int i = beholders.size() - 1; i >= 0; i--)
+    {
+        const monsters* mon = &menv[beholders[i]];
+        if (!_possible_beholder(mon))
+        {
+            beholders.erase(beholders.begin() + i);
+            removed = true;
+        }
+    }
+    if (removed)
+        _removed_beholder();
+}
+
+// Update a single beholder.
+void player::update_beholder(const monsters *mon)
+{
+    if (_possible_beholder(mon))
+        return;
+    for (unsigned int i = 0; i < beholders.size(); i++)
+        if (beholders[i] = mon->mindex())
+        {
+            beholders.erase(beholders.begin() + i);
+            _removed_beholder();
+            return;
+        }
+}
+
+// Helper function that resets the duration and messages if the player
+// is no longer mesmerised.
+void player::_removed_beholder()
+{
+    if (beholders.empty())
+    {
+        duration[DUR_MESMERISED] = 0;
+        mpr(coinflip() ? "You break out of your daze!"
+                       : "You are no longer entranced.",
+            MSGCH_DURATION);
+    }
+}
+
+// Helper function that checks whether the given monster is a possible
+// beholder.
+bool player::_possible_beholder(const monsters *mon) const
+{
+    if (silenced(you.pos()))
+        return (false);
+    if (!mon->alive() || !mons_near(mon) || mons_friendly(mon)
+        || mon->submerged() || mon->confused() || mons_cannot_move(mon)
+        || mon->asleep() || silenced(mon->pos()))
+    {
+        return (false);
+    }
+
+    // TODO: replace this by see/see_no_trans.
+    int walls = num_feats_between(you.pos(), mon->pos(),
+                                  DNGN_UNSEEN, DNGN_MAXOPAQUE);
+    if (walls > 0)
+        return (false);
+
+    return (true);
+}