fix(keys): Refactor to fix continuous use handling

saibotk · saibotk · commit f25aca2d9767 · 2026-01-18T02:20:22.000+01:00
We refactored the "use key handling" to correctly
work with entities that use the continuous use
functionality, like the health station.

Why?

Previous efforts to consolidate "use key handling"
led to a regression where continuous use
did not work as intended anymore when directly
looking at such an entity.

Though, it still worked when using the use key
in the proximity of the entity without directly
looking at it or running into it with the use
key held down, because the server then handled
the continuous use by itself.

This is behavior that the client cannot "block",
so we needed to refactor this code to use the
server-side continuous use handling as its only
source of truth again.

The root cause for this issue was that the client
suppressed further use handling after sending
the net message to the server, which caused the
server-side `KeyPressed` check to return false in
the timer.
Simply changing this would not be sufficient,
as we need still to suppress this handling for the
other use-cases, like weapon pickup or remote use.

Changes:

We mainly refactored the server-side
"use key handling" and client-side key suppression
to fix this issue and simplify the code.
Also, the continous use execution frequency is now
every tick again, instead of every 0.1 seconds.

The actual continuous execution is now handled by
solely by the server again.

The `TTT2PlayerUseEntity` net message code was
refactored to only handle its special cases like
spectator use, remote use and weapon pickup.
We send this message from within the bind handler
on the client if applicable.
This code is still necessary, as these are cases
where the normal use handling is not triggered
by the server due to the items being out of reach
or may not be correctly prioritized e.g.
the wrong weapon being picked up instead of
the intended looked at entity.

The corpse search and old `UseOverride` handling
was moved back to the original TTT way of handling
it, by utilizing the `KeyRelease` hook.
We did not modify the code here and merely copied
over the original code again.

Removed `ENT.CanUseKey` from placeable entities
as it is not needed anymore with the new handling.

Removed now obsolete `IsSpecialUsableEntity` and
`IsUsableEntity` functions.

Refactored `ClientUse` function to be client only
and always block further use handling.
This function is generally useful for client-side
only use key handling, e.g., for UI interactions.
E.g. the C4 uses this to open the C4 menu
when the use key is pressed while looking at it.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -20,6 +20,12 @@ All notable changes to TTT2 will be documented here. Inspired by [keep a changel
 - Fixed loading screen tips translation (by @mexikoedi)
 - Fixed missing `limit_left` translation (by @mexikoedi)
 - Fixed `GetHeadshotMultiplier` nil value error (by @mexikoedi)
+- Fixed continuous use not working correctly with entities like health stations (by @saibotk)
+
+### Removed / Breaking Changes
+
+- Removed `IsSpecialUsableEntity` & `IsUsableEntity` functions on entities (by @saibotk)
+- Changed `ENT:ClientUse()`: Removed return value, now always blocks the default use handling (by @saibotk)
 
 ## [v0.14.5b](https://github.com/TTT-2/TTT2/tree/v0.14.5b) (2025-08-18)
 
diff --git a/gamemodes/terrortown/entities/entities/ttt_base_placeable.lua b/gamemodes/terrortown/entities/entities/ttt_base_placeable.lua
@@ -14,8 +14,6 @@ ENT.isDestructible = true
 
 ENT.pickupWeaponClass = nil
 
-ENT.CanUseKey = true
-
 local soundDeny = Sound("HL2Player.UseDeny")
 
 ---
@@ -55,29 +53,6 @@ function ENT:PlayerCanPickupWeapon(activator)
     return true
 end
 
-if CLIENT then
-    ---
-    -- Hook that is called if a player uses their use key while focusing on the entity.
-    -- Implement this to predict early if entity can be picked up
-    -- @return bool True to prevent pickup
-    -- @realm client
-    function ENT:ClientUse()
-        local client = LocalPlayer()
-
-        if not IsValid(client) or not client:IsTerror() or not self.pickupWeaponClass then
-            return true
-        end
-
-        if not self:PlayerCanPickupWeapon(client) then
-            LANG.Msg("pickup_fail", nil, MSG_MSTACK_WARN)
-
-            self:EmitSound(soundDeny)
-
-            return true
-        end
-    end
-end -- CLIENT
-
 if SERVER then
     local soundRumble = {
         Sound("physics/concrete/concrete_break2.wav"),
diff --git a/gamemodes/terrortown/entities/entities/ttt_c4/shared.lua b/gamemodes/terrortown/entities/entities/ttt_c4/shared.lua
@@ -721,9 +721,7 @@ else -- CLIENT
     })
 
     ---
-    -- Hook that is called if a player uses their use key while focusing on the entity.
-    -- Shows C4 UI
-    -- @return bool True to prevent pickup
+    -- This is called if a player uses their use key while in proximity of the entity.
     -- @realm client
     function ENT:ClientUse()
         if IsValid(self) then
@@ -733,8 +731,6 @@ else -- CLIENT
                 ShowC4Disarm(self)
             end
         end
-
-        return true
     end
 
     ---
diff --git a/gamemodes/terrortown/entities/entities/ttt_hat_deerstalker.lua b/gamemodes/terrortown/entities/entities/ttt_hat_deerstalker.lua
@@ -11,8 +11,6 @@ ENT.PrintName = "hat_deerstalker_name"
 ENT.Model = Model("models/ttt/deerstalker.mdl")
 ENT.CanHavePrints = false
 
-ENT.CanUseKey = true
-
 ---
 -- @realm shared
 function ENT:SetupDataTables()
diff --git a/gamemodes/terrortown/entities/entities/ttt_health_station.lua b/gamemodes/terrortown/entities/entities/ttt_health_station.lua
@@ -198,19 +198,6 @@ else
         walkkey = Key("+walk", "WALK"),
     }
 
-    ---
-    -- Hook that is called if a player uses their use key while focusing on the entity.
-    -- Early check if client can use the health station
-    -- @return bool True to prevent pickup
-    -- @realm client
-    function ENT:ClientUse()
-        local client = LocalPlayer()
-
-        if not IsValid(client) or not client:IsPlayer() or not client:IsActive() then
-            return true
-        end
-    end
-
     -- handle looking at healthstation
     hook.Add("TTTRenderEntityInfo", "HUDDrawTargetIDHealthStation", function(tData)
         local client = LocalPlayer()
diff --git a/gamemodes/terrortown/gamemode/client/cl_keys.lua b/gamemodes/terrortown/gamemode/client/cl_keys.lua
@@ -26,7 +26,8 @@ function GM:OnSpawnMenuOpen()
 end
 
 ---
--- Runs when a bind has been pressed. Allows to block commands.
+-- Runs when a bind has been pressed. Allows blocking commands.
+-- @note This does not block continuous use activation on the server when running into the entity with +use already being pressed.
 -- @note By using the "alias" console command, this hook can be effectively circumvented
 -- @note To stop the user from using +attack, +left and any other movement commands
 -- of the sort, please look into using @{GM:StartCommand} instead
@@ -64,6 +65,17 @@ function GM:PlayerBindPress(ply, bindName, pressed)
             return true
         end
     elseif bindName == "+use" and pressed then
+        -- Handle special spectator use override
+        if ply:IsSpec() then
+            net.Start("TTT2PlayerUseEntity")
+            net.WriteEntity(nil)
+            net.WriteString("spectator_use")
+            net.SendToServer()
+
+            -- Suppress the +use bind
+            return true
+        end
+
         -- Do old traitor button check
         if TBHUD:PlayerIsFocused() then
             if ply:KeyDown(IN_WALK) then
@@ -76,47 +88,56 @@ function GM:PlayerBindPress(ply, bindName, pressed)
         end
 
         -- Find out if a marker is focused otherwise check normal use
-        local isClientOnly = false
-        local useEnt = markerVision.GetFocusedEntity()
-        local isRemote = IsValid(useEnt)
-        if not isRemote then
-            local shootPos = ply:GetShootPos()
-
-            local tr = util.TraceLine({
-                start = shootPos,
-                endpos = shootPos + ply:GetAimVector() * 100,
-                filter = ply,
-                mask = bit.bor(MASK_SOLID, CONTENTS_DEBRIS),
-            })
-
-            useEnt = tr.Entity
-
-            if not tr.Hit or not IsValid(useEnt) then
-                useEnt = nil
-            end
+        local markerVisionFocusedEnt = markerVision.GetFocusedEntity()
 
-            if useEnt and isfunction(useEnt.ClientUse) then
-                isClientOnly = useEnt:ClientUse()
-            end
-        elseif isfunction(useEnt.RemoteUse) then
+        if IsValid(markerVisionFocusedEnt) and isfunction(markerVisionFocusedEnt.RemoteUse) then
             sound.ConditionalPlay(soundUse, SOUND_TYPE_INTERACT)
 
-            isClientOnly = useEnt:RemoteUse(ply)
+            local clientSideOnly = markerVisionFocusedEnt:RemoteUse()
+
+            if not clientSideOnly then
+                -- Call this on the server too.
+                -- This cannot be done on the server's Entity:Use hook etc., because we suppress the +use bind here to not trigger it
+                -- on other close by entities.
+
+                net.Start("TTT2PlayerUseEntity")
+                net.WriteEntity(markerVisionFocusedEnt)
+                net.WriteString("remote_use")
+                net.SendToServer()
+            end
+
+            -- Suppress the +use bind here, so it does not trigger the Entity:Use hook on other close by entities.
+            -- Suppressing means, that the server will not see this key as being pressed anymore, even if the client is still pressing it.
+            return true
         end
 
-        -- If returned true by ClientUse or RemoteUse, then dont call Use and UseOverride or RemoteUse serverside
-        if isClientOnly then
+        -- This can sometimes deviate from the entity that the server actually uses.
+        -- But this is fine for now.
+        -- See https://github.com/Facepunch/garrysmod-issues/issues/5027
+        local clientUseEnt = ply:GetUseEntity()
+
+        -- Handle client side use methods
+        -- E.g. for showing client side UIs on interaction
+        if IsValid(clientUseEnt) and isfunction(clientUseEnt.ClientUse) then
+            clientUseEnt:ClientUse()
+
             return true
         end
 
-        if IsValid(useEnt) and (ply:IsSpec() or useEnt:IsSpecialUsableEntity()) then
+        -- Handle special weapon pickup use override
+        local trace = util.QuickTrace(ply:GetShootPos(), ply:GetAimVector() * 100, ply)
+
+        if IsValid(trace.Entity) and trace.Entity:IsWeapon() then
             net.Start("TTT2PlayerUseEntity")
-            net.WriteEntity(useEnt)
-            net.WriteBool(isRemote)
+            net.WriteEntity(trace.Entity)
+            net.WriteString("weapon_pickup")
             net.SendToServer()
 
+            -- Suppress the +use bind
             return true
         end
+
+        -- Otherwise the +use is executed as usual, triggering the server-side Entity:Use function.
     elseif string.sub(bindName, 1, 4) == "slot" and pressed then
         local idx = tonumber(string.sub(bindName, 5, -1)) or 1
 
diff --git a/gamemodes/terrortown/gamemode/server/sv_entity.lua b/gamemodes/terrortown/gamemode/server/sv_entity.lua
@@ -2,14 +2,6 @@
 -- @ref https://wiki.facepunch.com/gmod/Entity
 -- @class Entity
 
--- Caps taken from here: https://github.com/ValveSoftware/source-sdk-2013/blob/55ed12f8d1eb6887d348be03aee5573d44177ffb/mp/src/game/shared/baseentity_shared.h#L21-L38
-FCAP_IMPULSE_USE = 16
-FCAP_CONTINUOUS_USE = 32
-FCAP_ONOFF_USE = 64
-FCAP_DIRECTIONAL_USE = 128
-FCAP_USE_ONGROUND = 256
-FCAP_USE_IN_RADIUS = 512
-
 local safeCollisionGroups = {
     [COLLISION_GROUP_WEAPON] = true,
 }
@@ -78,38 +70,6 @@ function entmeta:Spawn()
     oldSpawn(self)
 end
 
----
--- Checks if the entity has any use functionality attached. This can be attached in the engine/via hammer or by
--- setting `.CanUseKey` to true. Player ragdolls and weapons always have use functionality attached.
--- @param[default=0] number requiredCaps Use caps that are required for this entity
--- @return boolean Returns true if the entity is usable by the player
--- @ref https://github.com/ValveSoftware/source-sdk-2013/blob/0d8dceea4310fde5706b3ce1c70609d72a38efdf/sp/src/game/server/player.cpp#L2766C71-L2781
--- @realm server
-function entmeta:IsUsableEntity(requiredCaps)
-    requiredCaps = requiredCaps or 0
-
-    -- special case: TTT specific lua based use interactions
-    -- when we're looking for specifically the lua use
-    if self:IsSpecialUsableEntity() then
-        return true
-    end
-
-    local caps = self:ObjectCaps()
-
-    if
-        bit.band(
-                caps,
-                bit.bor(FCAP_IMPULSE_USE, FCAP_CONTINUOUS_USE, FCAP_ONOFF_USE, FCAP_DIRECTIONAL_USE)
-            )
-            > 0
-        and bit.band(caps, requiredCaps) == requiredCaps
-    then
-        return true
-    end
-
-    return false
-end
-
 ---
 -- Some sounds are important enough that they shouldn't be affected by CPASAttenuationFilter
 -- @param string snd The name of the sound to be played
diff --git a/gamemodes/terrortown/gamemode/server/sv_player.lua b/gamemodes/terrortown/gamemode/server/sv_player.lua
diff --git a/gamemodes/terrortown/gamemode/shared/sh_entity.lua b/gamemodes/terrortown/gamemode/shared/sh_entity.lua
