Vector3 to UDim2? [Discussion]

Stravant has a ScreenSpace module script which contains multiple functions for interactions between the 2D screen and the 3D environment. I'll give you the function from the module that deals with what you're asking for:

local M = game.Players.LocalPlayer:GetMouse()
local Cam = game.Workspace.CurrentCamera

function WorldToScreen(Pos) --This function gets a World Position (Pos) and returns a Vector2 value of the screen coordinates
	local point = Cam.CoordinateFrame:pointToObjectSpace(Pos)
	local aspectRatio = M.ViewSizeX / M.ViewSizeY
	local hfactor = math.tan(math.rad(Cam.FieldOfView) / 2)
	local wfactor = aspectRatio*hfactor

	local x = (point.x/point.z) / -wfactor
	local y = (point.y/point.z) /  hfactor

	return Vector2.new(M.ViewSizeX * (0.5 + 0.5 * x), M.ViewSizeY * (0.5 + 0.5 * y))
end

local Vec2 = WorldToScreen(Vector3.new(0, 50, 0)) --Replace Vector3.new(0, 50, 0) with whatever vector3/position you want

Gui.Position = UDim2.new(0, Vec2.X, 0, Vec2.Y) --Since the function doesn't return a UDim2 value, you have to create a Udim2 value and put the X and Y of the Vector2 into that UDim2.

Hope this helped!

Note: This only works if it's in a localscript. Also, the Vector2 will be the coordinates of the point from the top left corner of the screen, so if the gui is located in another gui that's offset from the (0, 0), the gui will be positioned incorrectly.