RunService

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Not Replicated

Roblox Script Security

Read Parallel

Properties inherited from Instance

Methods

BindToRenderStep

void

The BindToRenderStep function binds a custom function to be called at a specific time during the render step. There are three main arguments for BindToRenderStep: name, priority, and what function to call.

As it is linked to the client's rendering process, BindToRenderStep can only be called on the client.

Name

The name parameter is a label for the binding, and can be used with RunService:UnbindFromRenderStep() if the binding is no longer needed.


local RunService = game:GetService("RunService")

local function functionToBind() end

-- Bind the function above to the binding named "tempBinding"
RunService:BindToRenderStep("tempBinding", 1, functionToBind)
-- Unbind the function bound to "tempBinding"
RunService:UnbindFromRenderStep("tempBinding")

Priority

The priority of the binding is an integer, and determines when during the render step to call the custom function. The lower this number, the sooner the custom function will be called. If two bindings have the same priority the Roblox engine will randomly pick one to run first. The default Roblox control scripts run with these specific priorities:

Player Input: 100
Camera Controls: 200 For convenience, the RenderPriority enum can be used to determine the integer value to set a binding. For example, to make a binding right before the default camera update, simply subtract 1 from the camera priority level.

When using Enum.RenderPriority, remember to use InlineCode.Value at the end of the desired enum. BindToRenderStep will not work if just the enum on its own is used.


local RunService = game:GetService("RunService")

local function beforeCamera(delta)
	-- Code in here will run before the default Roblox camera script
end

RunService:BindToRenderStep("Before camera", Enum.RenderPriority.Camera.Value - 1, beforeCamera)

Custom Function and Delta Time

The last argument of BindToRenderStep is the custom function to call. This function will be passed one parameter called deltaTime. DeltaTime shows how much time passed between the beginning of the previous render step and the beginning of the current render step.

All rendering updates will wait until the code in the render step finishes. Make sure that any code called by BindToRenderStep runs quickly and efficiently. If code in BindToRenderStep takes too long, then the game visuals will be choppy.

Parameters

name: string

The name parameter is a label for the binding, and can be used with RunService.Unbind if the binding is no longer needed.

priority: number

The priority of the binding is an integer, and determines when during the render step to call the custom function. The lower this number, the sooner the custom function will be called. If two bindings have the same priority the Roblox engine will randomly pick one to run first. The default Roblox control scripts run with these specific priorities:

Player Input: 100
Camera Controls: 200

For convenience, the RenderPriority enum can be used to determine the integer value to set a binding. For example, to make a binding right before the default camera update, simply subtract 1 from the camera priority level.

function: function

The custom function being bound.

Returns

void

Code Samples

Frame Moving in Circle

local RunService = game:GetService("RunService")

-- How fast the frame ought to move
local SPEED = 2

local frame = script.Parent
frame.AnchorPoint = Vector2.new(0.5, 0.5)

-- A simple parametric equation of a circle
-- centered at (0.5, 0.5) with radius (0.5)
local function circle(t)
	return 0.5 + math.cos(t) * 0.5, 0.5 + math.sin(t) * 0.5
end

-- Keep track of the current time
local currentTime = 0
local function onRenderStep(deltaTime)
	-- Update the current time
	currentTime = currentTime + deltaTime * SPEED
	-- ...and the frame's position
	local x, y = circle(currentTime)
	frame.Position = UDim2.new(x, 0, y, 0)
end

-- This is just a visual effect, so use the "Last" priority
RunService:BindToRenderStep("FrameCircle", Enum.RenderPriority.Last.Value, onRenderStep)
--RunService.RenderStepped:Connect(onRenderStep) -- Also works, but not recommended

RunService Custom Function

local RunService = game:GetService("RunService")

local function checkDelta(deltaTime)
	print("Time since last render step:", deltaTime)
end

RunService:BindToRenderStep("Check delta", Enum.RenderPriority.First.Value, checkDelta)

Bind and Unbind a Function

local RunService = game:GetService("RunService")

-- Step 1: Declare the function and a name
local name = "Print Hello"
local function printHello()
	print("Hello")
end

-- Step 2: Bind the function
RunService:BindToRenderStep(name, Enum.RenderPriority.First.Value, printHello)

-- Step 3: Unbind the function
local success, message = pcall(function()
	RunService:UnbindFromRenderStep(name)
end)

if success then
	print("Success: Function unbound!")
else
	print("An error occurred: " .. message)
end

GetCoreScriptVersion

Roblox Script Security

Returns

GetRobloxClientChannel

Roblox Script Security

Returns

GetRobloxVersion

Roblox Script Security

Returns

IsClient

This function returns whether the current environment is running on the client.

If the code that invoked this method is running in a client context (in a LocalScript or a ModuleScript required by a LocalScript) then this method will return true. In all other cases, this function will return false.

If this function returns true, then the current environment can access client-only features like RunService.RenderStepped or Players.LocalPlayer.

RunService test function results

Environment	IsStudio	IsClient	IsServer	IsEdit	IsRunning	IsRunMode
Live Player	false	true	false
Live Server	false	false	true
Edit Mode	true	true	true	true	false	false
Edit Mode (Team Create)	true	true	false	true	false	false
Run Mode	true	true	true	false	true	true
Play Mode (Client)	true	true	false	false	true	false
Play Mode (Server)	true	false	true	false	true	true
Team Test Player	true	true	false	false	true	false
Legacy Play Mode †	true	true	true	false	true	false

† 'Legacy Play Mode' refers to Play Mode with Accurate Play Solo disabled

See also:

Returns

Whether the current environment is running the client.

Code Samples

Run Context

local RunService = game:GetService("RunService")

if RunService:IsStudio() then
	print("I am in Roblox Studio")
else
	print("I am in an online Roblox Server")
end

if RunService:IsRunMode() then
	print("Running in Studio")
end

if RunService:IsClient() then
	print("I am a client")
else
	print("I am not a client")
end

if RunService:IsServer() then
	print("I am a server")
else
	print("I am not a server")
end

if RunService:IsRunning() then
	print("The game is running")
else
	print("The game is stopped or paused")
end

IsEdit

Plugin Security

This function returns whether the current environment is in 'Edit' mode. For example, Roblox Studio is in 'Edit Mode' when the game is not running.

IsEdit will return the inverse of RunService:IsRunning() with one exception, if the simulation has been 'paused' then both IsEdit and RunService:IsRunning() will return false.

See also:

Returns

Whether the current environment is in Edit mode.

IsRunMode

This function returns whether the 'Run' button has been pressed to run the simulation in Roblox Studio.

If the user has pressed 'Run', then this function will return true. This function will continue to return true if the simulation has been paused using the 'Pause' button. However, once it has been stopped using the 'Stop' button it will revert to returning false.

Roblox Studio only enters run mode when the 'Run' button is pressed, not the 'Play' button. This function will also return false if the simulation was started using RunService:Run() rather than the 'Run' button.

RunService test function results

See also:

Returns

Whether the 'Run' button has been pressed to run the simulation in Roblox Studio.

Code Samples

Run Context

local RunService = game:GetService("RunService")

if RunService:IsStudio() then
	print("I am in Roblox Studio")
else
	print("I am in an online Roblox Server")
end

if RunService:IsRunMode() then
	print("Running in Studio")
end

if RunService:IsClient() then
	print("I am a client")
else
	print("I am not a client")
end

if RunService:IsServer() then
	print("I am a server")
else
	print("I am not a server")
end

if RunService:IsRunning() then
	print("The game is running")
else
	print("The game is stopped or paused")
end

IsRunning

Returns whether the game is currently running

The game is considered running when it is not in edit mode in Roblox Studio. This means, if the simulation has been run using the 'Run' or 'Play' buttons the game is running.

IsRunning will always return the inverse of RunService:IsEdit() with one exception, if the simulation has been 'paused' then both RunService:IsEdit() and IsRunning will return false.

RunService test function results

See also:

Returns

Whether the game is currently running.

Code Samples

Run Context

local RunService = game:GetService("RunService")

if RunService:IsStudio() then
	print("I am in Roblox Studio")
else
	print("I am in an online Roblox Server")
end

if RunService:IsRunMode() then
	print("Running in Studio")
end

if RunService:IsClient() then
	print("I am a client")
else
	print("I am not a client")
end

if RunService:IsServer() then
	print("I am a server")
else
	print("I am not a server")
end

if RunService:IsRunning() then
	print("The game is running")
else
	print("The game is stopped or paused")
end

IsServer

This function returns whether the current environment is running on the server.

If the code that invoked this method is running in a server context (in a Script or a ModuleScript required by a Script) then this method will return true. In all other cases, this function will return false.

If this function returns true, then the current environment can access server-only features like ServerStorage or ServerScriptService.

See also:

Returns

Whether the current environment is running on the server.

Code Samples

Run Context

local RunService = game:GetService("RunService")

if RunService:IsStudio() then
	print("I am in Roblox Studio")
else
	print("I am in an online Roblox Server")
end

if RunService:IsRunMode() then
	print("Running in Studio")
end

if RunService:IsClient() then
	print("I am a client")
else
	print("I am not a client")
end

if RunService:IsServer() then
	print("I am a server")
else
	print("I am not a server")
end

if RunService:IsRunning() then
	print("The game is running")
else
	print("The game is stopped or paused")
end

IsStudio

This function returns whether the current environment is running in Roblox Studio.

This function will only return true when using Roblox Studio and can be used to add code to test your game within Studio.

See also:

Returns