Cleave effect for Axes.

* Additional targets are acquired by rotating from the main target in both
  directions but no more than 3 cells. Solid features block cleaving. On
  open grounds, it attacks 7 cells (all but the opposite one from the main
  target).
  A single wall on the side can block one or two targets since it doesn't go
  all around.
* Additional attacks do 75% damage. Main target still takes full damage.
* Allies don't block cleaving and are not harmed by it unless attacker
  is confused.
* Monsters wielding axes get cleaving too.
* Broad axe, battleaxe and executioner's axe base damage is reduced by 1.
  More nerfing might be needed for the latter 2.
* Cleaving works when attacking empty spaces (useful against invisible
  monsters)
* Monsters dual wielding axes should work.

Thanks to LexAckson for helping with this implementation
(especially rotate_adjacent).

1 files changed, 13 insertions, 0 deletions

diff --git a/crawl-ref/source/coord.cc b/crawl-ref/source/coord.cc
index dfd6c20645..144420e6c2 100644
--- a/crawl-ref/source/coord.cc
+++ b/crawl-ref/source/coord.cc
@@ -80,3 +80,16 @@ coord_def grid2player(const coord_def &gc)
 {
     return (gc - you.pos());
 }
+
+//rotates a coord_def that points to an adjacent square
+//clockwise (direction > 0), or counter-clockwise (direction < 0)
+coord_def rotate_adjacent(coord_def vector, int direction)
+{
+    int xn, yn;
+
+    xn = vector.x - sgn(direction) * vector.y;
+    yn = sgn(direction) * vector.x + vector.y;
+    vector.x = xn;
+    vector.y = yn;
+    return vector.sgn();
+}