Give giant spores a chance of spawning ballistos while wandering

Give giant spores a chance of creating a ballistomycete when they move
while wandering. This ability is on a timer, so they can't create more
than 1 ballisto per 20 turns. Numbers may need tweaking.

1 files changed, 35 insertions, 0 deletions

diff --git a/crawl-ref/source/mon-abil.cc b/crawl-ref/source/mon-abil.cc
index 73d0547f6c..3c93b540a2 100644
--- a/crawl-ref/source/mon-abil.cc
+++ b/crawl-ref/source/mon-abil.cc
@@ -1435,4 +1435,39 @@ void mon_nearby_ability(monsters *monster)
     }
 }
 
+// When giant spores move (while wandering) maybe place a spore on the
+// square they move off of.
+void ballisto_on_move(monsters * monster, const coord_def & position)
+{
+    if (monster->type == MONS_GIANT_SPORE
+        && monster->behaviour ==  BEH_WANDER)
+    {
+        // The number field is used as a cooldown timer for this behavior.
+        if (monster->number <= 0)
+        {
+            if (one_chance_in(4))
+            {
+                 int rc = create_monster(mgen_data(MONS_BALLISTOMYCETE,
+                                                  SAME_ATTITUDE(monster),
+                                                  0,
+                                                  0,
+                                                  position,
+                                                  MHITNOT,
+                                                  MG_FORCE_PLACE));
+
+                if (rc != -1 && you.can_see(&env.mons[rc]))
+                {
+                    mprf("A ballistomycete grows in the wake of the spore.");
+                }
+                monster->number = 20;
+            }
+        }
+        else
+        {
+            monster->number--;
+        }
+
+    }
+}
+