How to fix my raycast?

[Cbrrah (Cbrah)]

I’m making a building system right now.

I am trying to make a script that moves a part parallel to a surface. However, as you can see in the video below, it’s slightly inaccurate for some reason. If anyone is aware of a fix, feel free to let me know. Thank you!

Code:

local UserInputService = game:GetService ("UserInputService")

local Part = workspace:WaitForChild("MovePart")

local Player = game:GetService ("Players").LocalPlayer
local Camera = workspace.CurrentCamera

local Params = RaycastParams.new ()
Params.FilterType = Enum.RaycastFilterType.Exclude
Params.FilterDescendantsInstances = {Player.Character, Part}

UserInputService.InputChanged:Connect (function (input, gameProcessed)
	if gameProcessed or input.UserInputType ~= Enum.UserInputType.MouseMovement then
		return

	end

	local mouseLocation = UserInputService:GetMouseLocation ()

	local unitRay = Camera:ScreenPointToRay (mouseLocation.X, mouseLocation.Y)
	local result = workspace:Raycast (unitRay.Origin, unitRay.Direction * 500, Params)

	if result and result.Instance then
		local roundedPosition = Vector3.new (math.round (result.Position.X), math.round(result.Position.Y), math.round (result.Position.Z))

		game:GetService("TweenService"):Create(Part, TweenInfo.new(0.1), {Position = roundedPosition + result.Normal * (Part.Size / 2)}):Play()
	end
end)

Thanks again guys!!

[syyIvi (sriracha)]

seen this trick where you bump the y mouse location up by 26 pixels for some reason… try it out
might have something to do with the top bar idk

[ErrorBuilds]

@Cbrrah

game:GetService("TweenService"):Create(Part, TweenInfo.new(0.1), {Position = roundedPosition + result.Normal * (Part.Size / 2)}):Play()

I’m not very sure, but using the tweens might cancel eachother out.
Try setting the position of the part.

[Cbrrah (Cbrah)]

Just tried this. Unfortunately it still yields the same results. Any further suggestions?

[ErrorBuilds]

Just went into studio and tested out your script, except I changed
local unitRay = Camera:ScreenPointToRay (mouseLocation.X, mouseLocation.Y)
to
local unitRay = Camera:ViewportPointToRay(mouseLocation.X, mouseLocation.Y)

and it was a bit more accurate than before.

I’m pretty sure Camera:ScreenPointToRay() accounts for the top bar, like what @syylvi was saying.

[Cbrrah (Cbrah)]

Great job! That’s really interesting.
Great solution.

[NoDripDylan1 (Dylan)]

use viewportpointtoray instead of screen