Make trees and plants block opacity_no_trans.

opacity_no_trans is used for you.trans_wall_block, which in turn
is used in monster pathfinding. This fixes some pathfinding issues
in the new woody swamp. If the "no_trans" opacity is used for
other purposes, this change may also have negative side-effects.

1 files changed, 23 insertions, 6 deletions

diff --git a/crawl-ref/source/losparam.cc b/crawl-ref/source/losparam.cc
index ff53d43543..53823ce28e 100644
--- a/crawl-ref/source/losparam.cc
+++ b/crawl-ref/source/losparam.cc
@@ -38,18 +38,35 @@ opacity_type opacity_fullyopaque::operator()(const coord_def& p) const
         return OPC_CLEAR;
 }
 
-// Make transparent walls block in addition to normal LOS.
+static bool mons_block_no_trans(const monsters* mons)
+{
+    if (mons == NULL)
+        return false;
+
+    switch (mons->id())
+    {
+    case MONS_BUSH:
+    case MONS_PLANT:
+    case MONS_OKLOB_PLANT:
+    case MONS_FUNGUS:
+        return true;
+    default:
+        return false;
+    }
+}
+
+// Make transparent obstacles block in addition to normal LOS.
+// This is used for example for monster pathfinding, so things
+// that should be walked around should be opaque.
 opacity_type opacity_no_trans::operator()(const coord_def& p) const
 {
     dungeon_feature_type f = env.grid(p);
-    if (feat_is_opaque(f) || feat_is_wall(f))
+    if (feat_is_opaque(f) || feat_is_wall(f) || f == DNGN_TREES)
+        return OPC_OPAQUE;
+    else if (mons_block_no_trans(monster_at(p)))
         return OPC_OPAQUE;
     else if (is_opaque_cloud(env.cgrid(p)))
         return OPC_HALF;
-    else if (f == DNGN_TREES)
-        return OPC_HALF;
-    else if (monster_at(p) && monster_at(p)->type == MONS_BUSH)
-        return OPC_HALF;
     else
         return OPC_CLEAR;
 }