Attempt to perform arithmetic (sub) on Instance and Vector3

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#1

Hello,
I’ve encountered this error and has been searching devforum for the answer, yet I can’t seem to find the error. I’m trying to make a throwable knife using raycast. But, I believe it thinks the mouse position is an instance. How it works is…

How it works
  • Input
  • Fires bindable event
  • Receives events then creates ray and fires client
  • Client receives and creates the visual

Here’s the script of the raycast:

game:GetService("ReplicatedStorage"):WaitForChild("ConnectorEvent").Event:Connect(function(player,mousePos)
	local character = player.Character
	
	local raycastParams = RaycastParams.new()
	raycastParams.FilterType = Enum.RaycastFilterType.Blacklist
	raycastParams.FilterDescendantsInstances = {character}
	
	local Handle =  character.Sword:WaitForChild("Handle")
	local startPos = Handle.Position
	local endPos = (mousePos-startPos).Unit*50
	local raycastResult = workspace:Raycast(startPos, endPos,raycastParams)
	local hitPart = raycastResult.Instance

	if raycastResult then
		if hitPart:FindFirstChild("Humanoid") then
			hitPart.Humanoid:TakeDamage(100)
		end
		game:GetService("ReplicatedStorage"):WaitForChild("ProjectileEvent"):FireAllClients(startPos,endPos)
	end
end)

Thank you for reading.

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#2

Would you mind sending an screenshot of the full error?

#3

This is the only subtract operation I can find.
What is mousePos set to? Send a screenshot on where it’s set.

#4

Ok sure the full error is:
ServerScriptService.ConnectorScript:10: attempt to perform arithmetic (sub) on Instance and Vector3
And mouse pos is:
mouse.Hit.p

Would it be in error if I fire the remote event with the player variable in it? Because now I’m thinking it could be because it thinks the player is the mousePos.

#5

(that’s the same thing, the stack traces would be in a screenshot, BUT NOT NEEDED ANYMORE, because i can confirm what’s going on)

Well, it can’t be. The error is saying that you’re trying to do a subtract operation using an Instance and a Vector3. (While you can do Vector3 - Vector3, you can’t subtract from an instance)

An instance is anything on the explorer, so, the workspace, a part, a service, like ReplicatedStorage, etc.

Also Mouse.Hit.Position is better than Mouse.Hit.p (.p is deprecated)

1 Like
#6

Oh.
Yeah uh, this is a BindableEvent. It’s not server - sided, or client - sided, arguments you pass, are just arguments you pass, it’s kind of just a normal event. You’re supposed to fire it with the player argument if you’re listening to a player argument. That’s the issue, a player is an instance.

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