From 435643b958de61a9630b131804147a3a80eefaa0 Mon Sep 17 00:00:00 2001
From: Louis-Antoine <lamr@free.fr>
Date: Mon, 18 May 2020 16:16:45 +0200
Subject: [PATCH] Fix P_GetZAt for Lua

---
 src/lua_baselib.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/lua_baselib.c b/src/lua_baselib.c
index 519801f2f6..d56f49a5b0 100644
--- a/src/lua_baselib.c
+++ b/src/lua_baselib.c
@@ -2184,16 +2184,18 @@ static int lib_evStartCrumble(lua_State *L)
 
 static int lib_pGetZAt(lua_State *L)
 {
-	pslope_t *slope = *((pslope_t **)luaL_checkudata(L, 1, META_SLOPE));
 	fixed_t x = luaL_checkfixed(L, 2);
 	fixed_t y = luaL_checkfixed(L, 3);
 	//HUDSAFE
-	if (slope)
-		lua_pushfixed(L, P_GetSlopeZAt(slope, x, y));
-	else
+	if (lua_isnil(L, 1))
 	{
 		fixed_t z = luaL_checkfixed(L, 4);
-		lua_pushfixed(L, P_GetZAt(slope, x, y, z));
+		lua_pushfixed(L, P_GetZAt(NULL, x, y, z));
+	}
+	else
+	{
+		pslope_t *slope = *((pslope_t **)luaL_checkudata(L, 1, META_SLOPE));
+		lua_pushfixed(L, P_GetSlopeZAt(slope, x, y));
 	}
 
 	return 1;
-- 
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