From 9369b2b167da473c76e876be9565b84218fe2b0e Mon Sep 17 00:00:00 2001
From: "Eevee (Evelyn Woods)" <eevee.git@veekun.com>
Date: Mon, 10 May 2021 20:46:19 -0600
Subject: [PATCH] Partially restore Lynx force floor behavior

---
 js/defs.js      | 4 ++++
 js/game.js      | 6 +++---
 js/tiletypes.js | 9 +++++++++
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/js/defs.js b/js/defs.js
index 6fb0e7b..b7dc6a4 100644
--- a/js/defs.js
+++ b/js/defs.js
@@ -180,6 +180,10 @@ export const COMPAT_FLAGS = [
     key: 'no_backwards_override',
     label: "Player can't override backwards on a force floor",
     rulesets: new Set(['lynx']),
+}, {
+    key: 'force_floor_only_on_arrive',
+    label: "Force floors only affect actors when stepped on",
+    rulesets: new Set(['lynx', 'ms']),
 }, {
     key: 'traps_like_lynx',
     label: "Traps eject faster, and even when already open",
diff --git a/js/game.js b/js/game.js
index 191d6ff..eae1b56 100644
--- a/js/game.js
+++ b/js/game.js
@@ -1332,7 +1332,7 @@ export class Level extends LevelInterface {
             return null;
         if (! terrain.type.get_slide_direction)
             return null;
-        if (! (actor.is_pending_slide || terrain.type.slide_automatically))
+        if (! actor.is_pending_slide && ! (terrain.type.slide_automatically && ! this.compat.force_floor_only_on_arrive))
             return null;
         if (actor.ignores(terrain.type.name))
             return null;
@@ -1792,8 +1792,8 @@ export class Level extends LevelInterface {
         // does NOT act like a bonk (hence why it's here)
         if (this.compat.no_backwards_override) {
             let terrain = orig_cell.get_terrain()
-            if (terrain.type.slide_mode === 'force' && ! actor.ignores(terrain.type.name) &&
-                direction === DIRECTIONS[actor.direction].opposite)
+            if (! actor.ignores(terrain.type.name) &&
+                terrain.type.force_floor_direction === DIRECTIONS[direction].opposite)
             {
                 return false;
             }
diff --git a/js/tiletypes.js b/js/tiletypes.js
index 4791122..745d06a 100644
--- a/js/tiletypes.js
+++ b/js/tiletypes.js
@@ -62,6 +62,11 @@ function _define_force_floor(direction, opposite_type) {
         get_slide_direction(me, level, other) {
             return direction;
         },
+        force_floor_direction: direction,
+        on_arrive(me, level, other) {
+            // Necessary for compat.force_floor_only_on_arrive, which disables slide_automatically
+            level._set_tile_prop(other, 'is_pending_slide', true);
+        },
         activate(me, level) {
             level.transmute_tile(me, opposite_type);
         },
@@ -984,6 +989,10 @@ const TILE_TYPES = {
             return (level.compat.rff_blocks_monsters &&
                 (other.type.collision_mask & COLLISION.monster_typical));
         },
+        on_arrive(me, level, other) {
+            // Necessary for compat.force_floor_only_on_arrive, which disables slide_automatically
+            level._set_tile_prop(other, 'is_pending_slide', true);
+        },
     },
     slime: {
         layer: LAYERS.terrain,