How do I detect if a player is moving forwards or backwards

[wf_sh (wait)]

Currently I have this small code that I have made

    print(hrp.CFrame.LookVector)
	print(h.MoveDirection)
	
	local push = Instance.new("BodyVelocity")
	push.MaxForce = Vector3.new(1,1,1) * 1000000000
	
	local hx =  hrp.CFrame.LookVector.X
	local movex = h.MoveDirection.X
	
	if movex == 0 then
		push.Velocity = hrp.CFrame.LookVector * 35
	elseif hx > 0 and movex < 0 or hx < 0 and movex > 0 then
		push.Velocity = hrp.CFrame.LookVector * -35
	else
		push.Velocity = hrp.CFrame.LookVector * 35
	end
	
	push.Parent = hrp
	Debris:AddItem(push, 0.49)

Its purpose is to move a player forwards when run if they are moving forwards (or if they are standing still) and if they are moving backwards, move them backwards. However I have noticed this being inaccurate (players strafing slightly to the side while moving forwards makes them move backwards e.g)

Any ideas on how I can improve?
(h is referring to a humanoid and hrp is referring to a humanoid root part of a character)

[Davidiko_v (David)]

https://www.roblox.com/library/6820777966/Player-move-direction-detector-wasd?ViewInBrowser=true&CreatorId=557883847&SearchId=C4687FB7-9F28-4DAE-B421-A870252D8D5A&Category=Model&Position=1&SearchKeyword=&CreatorType=User&SortType=Relevance
This thing can give you movement of player by wasd and by this you can understand of player walking forward or backwards by W and S, this script works better when player is in first person.
Or you need script which works not only in first person?

[wf_sh (wait)]

Or you need script which works not only in first person?

My game is currently only third person.

[Davidiko_v (David)]

ok i just understanded, roblox dont change vector that fast so its a roblox bug i think and script pretty much works if player dont rotating with so big speed, you can test it yourself

[Tiwernik (Tiw)]

userinputservice, if its a server script consider using remoteevents (i dont know if this works im not very good at scripting)

[Sleazel]

Here is something I came up with, this should be a local script in StarterCharacterScripts. I prefer to use new body movers, but you might want to stick to BodyVelocity if you want. You do not need an attachment if that is the case. I wouldn’t relay on HumanoidRootPart for direction detection, due to strafing and “shift lock” players.

local hrp = script.Parent:WaitForChild("HumanoidRootPart")
local h = script.Parent:WaitForChild("Humanoid")

local att = Instance.new("Attachment")
att.Parent = hrp

local vf = Instance.new("VectorForce")
vf.Attachment0 = att
vf.Parent = hrp

local pushForce = 12500
local standStill = Vector3.new(0,0,-pushForce) 
local rs = game:GetService("RunService")

local connection = rs.Heartbeat:Connect(function()
	
	local x,z = h.MoveDirection.X, h.MoveDirection.Z
	if x == 0 and z == 0 then
		vf.Force = standStill
	else
		vf.Force = Vector3.new(-z*pushForce,0,-x*pushForce)
	end
	
end)

h.Died:Connect(function()
	connection:Disconnect()
end)