From a8a75fd0cabcb637c290d00f4f69f7789ae6f6c1 Mon Sep 17 00:00:00 2001
From: Zeno Rogue <zeno@attnam.com>
Date: Fri, 17 Apr 2026 17:42:11 +0200
Subject: [PATCH] fixed Vine Spirits sometimes considering some
 halfvine-related moves illegal

---
 celldrawer.cpp |  4 +---
 flags.cpp      |  5 +++++
 passable.cpp   | 15 +++------------
 3 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/celldrawer.cpp b/celldrawer.cpp
index 2f01f31e..d750ecef 100644
--- a/celldrawer.cpp
+++ b/celldrawer.cpp
@@ -987,9 +987,7 @@ void celldrawer::draw_grid_edge(int t, color_t col, int prec) {
 
 void celldrawer::draw_halfvine() {
 
-  int i =-1;
-  for(int t=0;t<6; t++) if(c->move(t) && c->move(t)->wall == c->wall)
-    i = t;
+  int i = halfvine_direction(c);
 
   qfi.spin = ddspin(c, i, M_PI/S3);
   shiftmatrix V2 = V * qfi.spin;
diff --git a/flags.cpp b/flags.cpp
index 98ec40ba..87f8b60c 100644
--- a/flags.cpp
+++ b/flags.cpp
@@ -413,4 +413,9 @@ EX bool looks_like_player(eMonster m) {
   return among(m, moPlayer, moMimic, moIllusion, moShadow);
   }
 
+EX int halfvine_direction(cell *c) {
+  for(int t=0; t<c->type; t++) if(c->move(t) && c->move(t)->wall == c->wall) return t;
+  return -1;
+  }
+
 }
diff --git a/passable.cpp b/passable.cpp
index a00c1631..662d4ea5 100644
--- a/passable.cpp
+++ b/passable.cpp
@@ -382,22 +382,13 @@ bool slimepassable(cell *w, cell *c) {
 
   // only travel to halfvines correctly
   if(cellHalfvine(c)) {
-    int i=0;
-    for(int t=0; t<c->type; t++) if(c->move(t) && c->move(t)->wall == c->wall) i=t;
-    int z = i-u; if(z<0) z=-z; z%=6;
-    if(z>1) return false;
-    hv=(group == ogroup);
+    if(angledist(c, halfvine_direction(c), u) > 1) return false;
     }
   // only travel from halfvines correctly
   if(cellHalfvine(w)) {
-    int i=0;
-    for(int t=0; t<w->type; t++) if(w->move(t) && w->move(t)->wall == w->wall) i=t;
-    int z = i-c->c.spin(u); if(z<0) z=-z; z%=6;
-    if(z>1) return false;
-    hv=(group == ogroup);
+    if(angledist(w, halfvine_direction(w), c->c.spin(u)) > 1) return false;
     }
-  if(!hv) return false;
-  return true;
+  return hv;
   }
 
 bool sharkpassable(cell *w, cell *c) {