How to make a smooth draggable gui in roblox?

Help and Feedback Scripting Support
#1

I’ve got a simple draggable script from Tiffblocks but I want to tween it somehow without it being glitchy. I’ve tried just simply using :TweenPosition but it’s pretty glitchy https://gyazo.com/cae70f6f0b6a04eeb9f7d923851ffae6

Any help is appreciated :grinning_face_with_smiling_eyes:

2 Likes
#2

Can you send the code you are currently using so I can help?

#3

I basically just used the code from the post I said and added a TweenPosition to it

local UserInputService = game:GetService("UserInputService")

local gui = script.Parent

local dragging
local dragInput
local dragStart
local startPos

local function update(input)
	local delta = input.Position - dragStart
	gui:TweenPosition(UDim2.new(startPos.X.Scale, startPos.X.Offset + delta.X, startPos.Y.Scale, startPos.Y.Offset + delta.Y), Enum.EasingDirection.InOut, Enum.EasingStyle.Sine, 0.04, true) -- This is what I changed
end

gui.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
		dragging = true
		dragStart = input.Position
		startPos = gui.Position

		input.Changed:Connect(function()
			if input.UserInputState == Enum.UserInputState.End then
				dragging = false
			end
		end)
	end
end)

gui.InputChanged:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseMovement or input.UserInputType == Enum.UserInputType.Touch then
		dragInput = input
	end
end)

UserInputService.InputChanged:Connect(function(input)
	if input == dragInput and dragging then
		update(input)
	end
end)
1 Like
#4

I used Linear Interpolation to smooth the movement.
a + (b - a) * m

local UserInputService = game:GetService("UserInputService")
local runService = (game:GetService("RunService"));

local gui = script.Parent

local dragging
local dragInput
local dragStart
local startPos

function Lerp(a, b, m)
	return a + (b - a) * m
end;

local DRAG_SPEED = (8); -- // The speed of the UI darg.
function Update(dt)
	local delta = UserInputService:GetMouseDelta()
	local xGoal = (startPos.X.Offset + delta.X);
	local yGoal = (startPos.Y.Offset + delta.Y);
	gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, xGoal, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, yGoal, dt * DRAG_SPEED))
end;

gui.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
		dragging = true
		dragStart = input.Position
		startPos = gui.Position

		input.Changed:Connect(function()
			if input.UserInputState == Enum.UserInputState.End then
				dragging = false
			end
		end)
	end
end)

gui.InputChanged:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseMovement or input.UserInputType == Enum.UserInputType.Touch then
		dragInput = input
	end
end)

runService.Heartbeat:Connect(Update)

If there are problems with it then tell.

3 Likes
#5

Now I’m getting the error
attempt to index nil with 'X'
On line 18

#6

Testing it myself, will edit it when found the bug.

#7

It looks like you’re running the Update function when startPos is still nil

#8

Fixed.

local UserInputService = game:GetService("UserInputService")
local runService = (game:GetService("RunService"));

local gui = script.Parent

local dragging
local dragInput
local dragStart
local startPos

function Lerp(a, b, m)
	return a + (b - a) * m
end;

local lastMousePos
local DRAG_SPEED = (8); -- // The speed of the UI darg.
function Update(dt)
	if not (dragging) then return end;
	if not (startPos) then return end;
	local delta = (lastMousePos - UserInputService:GetMouseLocation())
	local xGoal = (startPos.X.Offset - delta.X);
	local yGoal = (startPos.Y.Offset - delta.Y);
	gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, xGoal, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, yGoal, dt * DRAG_SPEED))
end;

gui.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
		dragging = true
		dragStart = input.Position
		startPos = gui.Position
		lastMousePos = UserInputService:GetMouseLocation()

		input.Changed:Connect(function()
			if input.UserInputState == Enum.UserInputState.End then
				dragging = false
			end
		end)
	end
end)

gui.InputChanged:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseMovement or input.UserInputType == Enum.UserInputType.Touch then
		dragInput = input
	end
end)

runService.Heartbeat:Connect(Update)

But if you stop dragging in the middle of dragging, it will kind of cut. Let me know if you need to fix that too.

4 Likes
#9

Thanks, it looks nice.

If it wouldn’t be too much trouble then that would make it look that much better.

1 Like
#10

I fixed that bug, now the UI should be smoothly dragged to where the position is even if stopped pressing in the middle.

local UserInputService = game:GetService("UserInputService")
local runService = (game:GetService("RunService"));

local gui = script.Parent

local dragging
local dragInput
local dragStart
local startPos

function Lerp(a, b, m)
	return a + (b - a) * m
end;

local lastMousePos
local lastGoalPos
local DRAG_SPEED = (8); -- // The speed of the UI darg.
function Update(dt)
	if not (dragging) then
		gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, lastGoalPos.X.Offset, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, lastGoalPos.Y.Offset, dt * DRAG_SPEED))
		return 
	end;
	
	if not (startPos) then return end;
	local delta = (lastMousePos - UserInputService:GetMouseLocation())
	local xGoal = (startPos.X.Offset - delta.X);
	local yGoal = (startPos.Y.Offset - delta.Y);
	lastGoalPos = UDim2.new(startPos.X.Scale, xGoal, startPos.Y.Scale, yGoal)
	gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, xGoal, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, yGoal, dt * DRAG_SPEED))
end;

gui.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
		dragging = true
		dragStart = input.Position
		startPos = gui.Position
		lastMousePos = UserInputService:GetMouseLocation()

		input.Changed:Connect(function()
			if input.UserInputState == Enum.UserInputState.End then
				dragging = false
			end
		end)
	end
end)

gui.InputChanged:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseMovement or input.UserInputType == Enum.UserInputType.Touch then
		dragInput = input
	end
end)

runService.Heartbeat:Connect(Update)

And no problem.

2 Likes
#11

With that I get the same attempt to index nil with 'X' but it still works :man_shrugging: Nevermind, fixed it by moving the if not (startPos) then return end; to line 19

local UserInputService = game:GetService("UserInputService")
local runService = (game:GetService("RunService"));

local gui = script.Parent

local dragging
local dragInput
local dragStart
local startPos

function Lerp(a, b, m)
	return a + (b - a) * m
end;

local lastMousePos
local lastGoalPos
local DRAG_SPEED = (8); -- // The speed of the UI darg.
function Update(dt)
	if not (startPos) then return end;
	if not (dragging) then
		gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, lastGoalPos.X.Offset, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, lastGoalPos.Y.Offset, dt * DRAG_SPEED))
		return 
	end;
	
	local delta = (lastMousePos - UserInputService:GetMouseLocation())
	local xGoal = (startPos.X.Offset - delta.X);
	local yGoal = (startPos.Y.Offset - delta.Y);
	lastGoalPos = UDim2.new(startPos.X.Scale, xGoal, startPos.Y.Scale, yGoal)
	gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, xGoal, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, yGoal, dt * DRAG_SPEED))
end;

gui.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
		dragging = true
		dragStart = input.Position
		startPos = gui.Position
		lastMousePos = UserInputService:GetMouseLocation()

		input.Changed:Connect(function()
			if input.UserInputState == Enum.UserInputState.End then
				dragging = false
			end
		end)
	end
end)

gui.InputChanged:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseMovement or input.UserInputType == Enum.UserInputType.Touch then
		dragInput = input
	end
end)

runService.Heartbeat:Connect(Update)
#12

Fix.

local UserInputService = game:GetService("UserInputService")
local runService = (game:GetService("RunService"));

local gui = script.Parent

local dragging
local dragInput
local dragStart
local startPos

function Lerp(a, b, m)
	return a + (b - a) * m
end;

local lastMousePos
local lastGoalPos
local DRAG_SPEED = (8); -- // The speed of the UI darg.
function Update(dt)
	if not (startPos) then return end;
	if not (dragging) and (lastGoalPos) then
		gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, lastGoalPos.X.Offset, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, lastGoalPos.Y.Offset, dt * DRAG_SPEED))
		return 
	end;

	local delta = (lastMousePos - UserInputService:GetMouseLocation())
	local xGoal = (startPos.X.Offset - delta.X);
	local yGoal = (startPos.Y.Offset - delta.Y);
	lastGoalPos = UDim2.new(startPos.X.Scale, xGoal, startPos.Y.Scale, yGoal)
	gui.Position = UDim2.new(startPos.X.Scale, Lerp(gui.Position.X.Offset, xGoal, dt * DRAG_SPEED), startPos.Y.Scale, Lerp(gui.Position.Y.Offset, yGoal, dt * DRAG_SPEED))
end;

gui.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
		dragging = true
		dragStart = input.Position
		startPos = gui.Position
		lastMousePos = UserInputService:GetMouseLocation()

		input.Changed:Connect(function()
			if input.UserInputState == Enum.UserInputState.End then
				dragging = false
			end
		end)
	end
end)

gui.InputChanged:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.MouseMovement or input.UserInputType == Enum.UserInputType.Touch then
		dragInput = input
	end
end)

runService.Heartbeat:Connect(Update)

Edit: Edited code.

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