TweenService to rotate an object from a non-centered position

[seaz_n (seoyeon)]

Hello, all!

I am using TweenService to rotate a part in a certain direction, but I am having trouble figuring out how to have this rotation occur from the edge of a part (or any portion of the part that is not the center of it), with a motion similar to that of opening a trap door, or opening a door.

Is this possible to do with TweenService? If not, what alternatives are there?

[refightx (Jake)]

Just a thought not very experienced with pivots but I believe u can edit the pivot on the part/model and set it to a corner

[seaz_n (seoyeon)]

Not familiar with pivots. I’ll look into them to see if this the answer I’m looking for.

[refightx (Jake)]

I believe I am wrong, although, I may not be wrong, but I believe pivots are not for position just for a better fix for rotation of a model. I suggest you look into it to make sure I am not wrong.

[seaz_n (seoyeon)]

More research had me discover that TweenService is unable to create what I am trying to accomplish, so I’ll have to figure out a different method.

[refightx (Jake)]

Have you tried lerping? Also I’m confused do you want the rotation not be in the center?

[seaz_n (seoyeon)]

This is the rotation I am aiming for, with the red dot being the center. Imagine opening a lid on a box. Pretty much that.

[Tomi1231 (Chilly28)]

At this point, I would make a “custom tween”, which is actually somewhat simple, you can even keep using easing styles using TweenService:GetValue()

local TweenService = game:GetService("TweenService")
local RunService = game:GetService("RunService")

local function Tween(TweenFunction : (alpha : number) -> nil, Duration : number, EasingStyle : Enum.EasingStyle?, EasingDirection : Enum.EasingDirection)
	EasingStyle = EasingStyle or Enum.EasingStyle.Linear
	EasingDirection = EasingDirection or Enum.EasingDirection.Out
	
	local StartTime = os.clock()
	
	while true do 
		local alpha = math.min((os.clock() - StartTime)/Duration,1) -- Value that goes from 0 to 1 (0% to 100%). It also cannot go above 1 because of the math.min(Value,1)
		alpha = TweenService:GetValue(alpha, EasingStyle, EasingDirection)
		
		TweenFunction(alpha)
		if alpha == 1 then break end
		
		RunService.RenderStepped:Wait()
	end
end

--

local Part = game.Workspace.Part

local Origin = Part.CFrame

local StartPivot = Origin -- No pivot, other than the initial rotation of the part
local EndPivot = Origin * CFrame.Angles(0,math.pi/2,0) -- 90 degrees
local Offset = CFrame.new(0,0,4) -- Part is 4 studs from the pivot. Set this to Size/2, to make it rotate on the edge of the part

local TweenFunction = function(alpha : number)
	Part.CFrame = StartPivot:Lerp(EndPivot,alpha) * Offset
end

Tween(TweenFunction, 5, Enum.EasingStyle.Quad, Enum.EasingDirection.InOut)

There are different ways to make a custom tween thing. If you want your part to have a repeating motion, you can make that directly instead of looping the tween, or you could add to this by adding a looping boolean, etc

[Fox_2042 (real cat)]

try using this. it’s meant for models, but works with just parts, too. idk how good it is compared to solutions though, if it’s just one part.

[Fusionet]

TweenService can definitely be used to achieve your desired result. All you need to do is make sure the object is a model (even if it’s just one singular part), and create another (smaller) part that will act as the center (in this case put it on the edge).

1. Set the model’s PrimaryPart to the smaller part
2. Weld the descendants of the model to the Primary Part
3. Use TweenService on the PrimaryPart, the rest of the model will follow it’s movement.
4. Make sure the PrimaryPart is Anchored, and everything else is NOT anchored

This code can be used to weld all descendants of a model to it’s primary part.

function module:WeldDescendantsToPart(part1, part2)
	part2 = part2 or part1 -- if no part2 is provided, weld everything to part1
	for i, part in pairs(part1:GetDescendants()) do
		if part:IsA("BasePart") and part ~= part2 then
			part.Anchored = false
			local weld = Instance.new("WeldConstraint")
			weld.Part0 = part2
			weld.Part1 = part
			weld.Parent = part
		end
	end
end

WeldDescendantsToPart(model, model.PrimaryPart) --example call

--Tween the PrimaryPart

[seaz_n (seoyeon)]

I’ll check out both of these solutions and see what the result looks like, thank you all so much for the discussion!

[seaz_n (seoyeon)]

This solution ended up working out, but now I have a different issue revolving around using :PivotTo() and the tween. I’ll look into how I can fix that though; I appreciate all the responses here!