From 43cef901ce86fde3c42f48b382a45f2c41c29163 Mon Sep 17 00:00:00 2001
From: CapybaraExtravagante
 <110635252+CapybaraExtravagante@users.noreply.github.com>
Date: Sat, 11 Feb 2023 19:26:07 +0100
Subject: [PATCH] Fixes a bug where glide-size could become out of sync if you
 get unbuckled (#73150)

This fixes a bug where you could theoretically un-sync your glide-size
from your movespeed if you unbuckled. Currently, if you unbuckle, we use
a proc that's only used there which gets all of the slowdowns from all
of your movespeed modifiers. There's two problems with that:

1. We already have a variable with your movespeed (cached)
2. This proc does not check any of the conditionals that might make a
movespeed modifier not apply, such as whether or not you are flying, or
if you're immune to it for some other reason.

This means that in specific edge-cases you could mess up your
glide-size.

I have not actually seen this happen, but this seems like a better way
of doing it :)
---
 code/game/objects/buckling.dm                 | 2 +-
 code/modules/movespeed/_movespeed_modifier.dm | 7 -------
 2 files changed, 1 insertion(+), 8 deletions(-)

diff --git a/code/game/objects/buckling.dm b/code/game/objects/buckling.dm
index e222b451380..fcea40cd2ed 100644
--- a/code/game/objects/buckling.dm
+++ b/code/game/objects/buckling.dm
@@ -152,7 +152,7 @@
 	buckled_mob.set_buckled(null)
 	buckled_mob.set_anchored(initial(buckled_mob.anchored))
 	buckled_mob.clear_alert(ALERT_BUCKLED)
-	buckled_mob.set_glide_size(DELAY_TO_GLIDE_SIZE(buckled_mob.total_multiplicative_slowdown()))
+	buckled_mob.set_glide_size(DELAY_TO_GLIDE_SIZE(buckled_mob.cached_multiplicative_slowdown))
 	buckled_mobs -= buckled_mob
 	if(anchored)
 		REMOVE_TRAIT(buckled_mob, TRAIT_NO_FLOATING_ANIM, BUCKLED_TRAIT)
diff --git a/code/modules/movespeed/_movespeed_modifier.dm b/code/modules/movespeed/_movespeed_modifier.dm
index c5c5a457f48..fea932650f6 100644
--- a/code/modules/movespeed/_movespeed_modifier.dm
+++ b/code/modules/movespeed/_movespeed_modifier.dm
@@ -194,13 +194,6 @@ GLOBAL_LIST_EMPTY(movespeed_modification_cache)
 	for(var/id in movespeed_mod_immunities)
 		. -= id
 
-/// Calculate the total slowdown of all movespeed modifiers
-/mob/proc/total_multiplicative_slowdown()
-	. = 0
-	for(var/id in get_movespeed_modifiers())
-		var/datum/movespeed_modifier/M = movespeed_modification[id]
-		. += M.multiplicative_slowdown
-
 /// Checks if a move speed modifier is valid and not missing any data
 /proc/movespeed_data_null_check(datum/movespeed_modifier/M) //Determines if a data list is not meaningful and should be discarded.
 	. = TRUE