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GetMouseDelta

This function returns the change, in pixels, of the position of the player’s Mouse in the last rendered frame as a DataType/Vector2. This function only works if the mouse has been locked using the UserInputService.MouseBehavior property. If the mouse has not been locked, the returned DataType/Vector2 values will be zero.

The sensitivity of the mouse, determined in the client’s settings and UserInputService/MouseDeltaSensitivity, will influence the result.

As UserInputService is client-side only, this function can only be used in a LocalScript.

Returns

Return Type Summary

Change in movement of the mouse


Code Samples


Create a Custom CameraScript

By default, Roblox relies on a LocalScript, described [here][1], to control the user’s camera. However, this script can be overridden with a custom CameraScript. The example below demonstrates how to create a custom script to control the user’s camera using many of the UserInputService events.

The script is broken into two parts:

  1. Mobile camera events, which rely on touch events
  2. Non-mobile camera events, which rely on keyboard input and tracking the user’s movement

First, the camera script needs utility functions to setup the camera and set its Camera/CameraType|CameraType to Scriptable so that the script can control the camera. It also needs a function to update the camera when it moves, rotates, and zooms.

Using touch events allows us to track user input as they interact with the touchscreen on their mobile device. These events allow us to handle camera movement, rotation, and zoom.

The second half of the code sample adds camera support for players on desktop devices. When input begans, the function Input() checks that the state of the input is Enum/UserInputState|Enum.UserInputState.Begin to ignore all keypress inputs other than when the user first presses a key down. When the user presses I and O the camera zooms in and out. When the presses down and moves their left mouse button, the script Enum/MouseBehavior|locks the player’s mouse by changing the UserInputService/MouseBehavior property. The camera rotates according to the mouse’s UserInputService/GetMouseDelta|change in screen position. When the player moves their character, the camera moves with them.

All of the parts discussed above are combined and shown in the code sample below.

-- ========================================
-- GLOBAL VARIABLES
-- ========================================
local UserInputService = game:GetService("UserInputService")
local RunService = game:GetService("RunService")

-- The camera used by the LocalPlayer
local camera = game.Workspace.CurrentCamera

local players = game:GetService("Players")
local player = players.LocalPlayer
local character = player.CharacterAdded:Wait()
local torso = character:WaitForChild("Torso")
local playerPosition = torso.Position

local default_CameraPosition = torso.Position
local default_CameraRotation = Vector2.new(0,math.rad(-60))
local default_CameraZoom = 15

local cameraPosition = default_CameraPosition
local cameraRotation = default_CameraRotation
local cameraZoom = default_CameraZoom

local cameraRotationBounds = {math.rad(-81),math.rad(20)}
local cameraZoomBounds = nil --{10,200}
local touchDragSpeed = 0.15
local cameraSpeed = 0.1
local cameraRotateSpeed = 10
local cameraMouseRotateSpeed = 0.25
local cameraTouchRotateSpeed = 10
-- ========================================
-- ========================================





-- ========================================
-- UTILITY FUNCTIONS
-- ========================================
local function SetCameraMode()
camera.CameraType = "Scriptable"
camera.FieldOfView = 80
camera.CameraSubject = nil
end

local function UpdateCamera()
SetCameraMode()
local cameraRotationCFrame = CFrame.Angles(0, cameraRotation.X, 0)*CFrame.Angles(cameraRotation.Y, 0, 0)
camera.CFrame = cameraRotationCFrame + cameraPosition + cameraRotationCFrame*Vector3.new(0, 0, cameraZoom)
camera.Focus = camera.CFrame - Vector3.new(0, camera.CFrame.p.Y, 0)
end
-- ========================================
-- ========================================




-- ========================================
-- MOBILE CAMERA EVENTS
-- ========================================
-- Events used to control the camera for players using a mobile device

-- ====================
-- CAMERA MOVE
-- ====================
-- Fired by UserInputService.TouchPan
local lastTouchTranslation = nil
local function TouchMove(touchPositions, totalTranslation, velocity, state)
	if state == Enum.UserInputState.Change or state == Enum.UserInputState.End then
		local difference = totalTranslation - lastTouchTranslation
	cameraPosition = cameraPosition + Vector3.new(difference.X, 0, difference.Y)
		UpdateCamera()
	end
	lastTouchTranslation = totalTranslation
end

-- ====================
-- CAMERA ROTATE
-- ====================
-- Fired by UserInputService.TouchRotate
local lastTouchRotation = nil
local function TouchRotate(touchPositions, rotation, velocity, state)
if state == Enum.UserInputState.Change or state == Enum.UserInputState.End then
local difference = rotation - lastTouchRotation
cameraRotation = cameraRotation + Vector2.new(-difference,0)*math.rad(cameraTouchRotateSpeed*cameraRotateSpeed)
		UpdateCamera()
	end
lastTouchRotation = rotation
end

-- ====================
-- CAMERA ZOOM
-- ====================
-- Fired by UserInputService.TouchPinch
local lastTouchScale = nil
local function TouchZoom(touchPositions, scale, velocity, state)
	if state == Enum.UserInputState.Change or state == Enum.UserInputState.End then
		local difference = scale - lastTouchScale
		cameraZoom = cameraZoom * (1 + difference)
		if cameraZoomBounds ~= nil then
			cameraZoom = math.min(math.max(cameraZoom, cameraZoomBounds[1]), cameraZoomBounds[2])
		else
			cameraZoom = math.max(cameraZoom, 0)
end
		UpdateCamera()
	end
	lastTouchScale = scale
end

local function Input()
	UpdateCamera()
end
-- ========================================





-- ========================================
-- NON-MOBILE CAMERA EVENTS
-- ========================================

local function Input(inputObject)
	if inputObject.UserInputType == Enum.UserInputType.Keyboard then
		if inputObject.UserInputState == Enum.UserInputState.Begin then						
			-- ====================
			-- CAMERA ZOOM
			-- ====================
			-- (I) Zoom In
			if inputObject.KeyCode == Enum.KeyCode.I then
			 	cameraZoom = cameraZoom - 15
			elseif inputObject.KeyCode == Enum.KeyCode.O then
				cameraZoom = cameraZoom + 15
			end
		
			-- (O) Zoom Out
			if cameraZoomBounds ~= nil then
				cameraZoom = math.min(math.max(cameraZoom, cameraZoomBounds[1]), cameraZoomBounds[2])
			else
				cameraZoom = math.max(cameraZoom, 0)
			end
			
			UpdateCamera()
		end
	end
	
	-- ====================
	-- CAMERA ROTATE
	-- ====================
	local pressed = UserInputService:IsMouseButtonPressed(Enum.UserInputType.MouseButton1)
	if pressed then
		UserInputService.MouseBehavior = Enum.MouseBehavior.LockCurrentPosition
		local rotation = userInputService:GetMouseDelta()
		cameraRotation = cameraRotation + rotation*math.rad(cameraMouseRotateSpeed)
	else
		UserInputService.MouseBehavior = Enum.MouseBehavior.Default
	end
end

-- ====================
-- CAMERA MOVE
-- ====================
local function PlayerChanged()
	local movement = torso.Position - playerPosition
	cameraPosition = cameraPosition + movement
	playerPosition = torso.Position
		
	UpdateCamera()
end
-- ========================================
-- ========================================






-- ========================================
-- DEVICE CHECK
-- ========================================
-- Determine whether the user is on a mobile device

if UserInputService.TouchEnabled then
	-- The user is on a mobile device, use Touch events
UserInputService.TouchPan:Connect(TouchMove)
UserInputService.TouchRotate:Connect(TouchRotate)
UserInputService.TouchPinch:Connect(TouchZoom)
else
	
	-- The user is not on a mobile device use Input events
UserInputService.InputBegan:Connect(Input)
UserInputService.InputChanged:Connect(Input)
UserInputService.InputEnded:Connect(Input)

	-- Camera controlled by player movement
	wait(2)
	RunService:BindToRenderStep("PlayerChanged", Enum.RenderPriority.Camera.Value-1, PlayerChanged)
end	
-- ========================================
-- ========================================

Getting Mouse Delta

GetMouseDelta returns the current change in movement of the mouse as a Vector2, but only if the mouse is locked. If the mouse isn’t locked the values in the returned Vector2 will be zero. It measures any mouse movement in pixels from the last render step to the current render step. If the user has set their camera sensitivity to be higher or lower than 1 in the in-game menu this will affect the value returned by GetMouseDelta. The camera sensitivity is a multiplier to the amount the camera moves as a result of mouse input.

local runService = game:GetService("RunService")
local userInputService = game:GetService("UserInputService")
 
local function OnRenderStep()
    local delta = userInputService:GetMouseDelta()
    print("The mouse has moved", delta, "since the last step.")
end
 
RunService:BindToRenderStep("MeasureMouseMovement", Enum.RenderPriority.Input.Value, OnRenderStep)