How do I make a beam follow the players cursor?

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#1

I’m attempting to make a laser that will follow the players cursor, I know it has something to do with ray casting or something, but I have absolutely no idea how to use it.

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#2

i’d take a look at this
https://developer.roblox.com/en-us/api-reference/function/WorldRoot/Raycast
you would fire a raycast either on local or server and use a remote event to give the info to the server

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#3

or if a laser fires there constantly u would repeatedly give location to server so it can create a beam

#4

I see. And how exactly do I like, actually do this? Because as I said I absolutely have no idea how to use a Raycast, and I don’t know how to bind it to my beam.

#5 
local parameters = RayCastParams.new()
parameters.FilterDescendantInstances = {--thing not to be touched by beam, for example u could put player.Character here}
parameters.FilterType = Enum.RayCastFilterType.Blacklist
local startpos = --starting position
local endpos = --endposition
local ray = workspace:RayCast(startpos, (endpos - startpos).Unit, parameters)
if ray then
     print(ray.Instance)
else
     print("Ray didnt hit anything")
end

sorry for the late reply

#6

So do I just put this in the part with the beam in it?

Also there are 3 errors in the script, pardon me being a little dumb by the way, but I’m not sure how to fix these.
“W001: Unknown global ‘RayCastParams’.”
“Syntax error: Expected identifier when parsing expression, got ‘local’”
“Syntax error: Expected identifier when parsing expression, got ‘local’”

#7
  1. mb, it should be RaycastParams instead of RayCastParams and
  2. when i wrote what the starting position and ending position were supposed to be, did u change them to what i wrote there?
#8

Ah, right sorry. Must’ve slipped my mind, uh so what exactly do I do with the starting and ending position? Sorry once again I’m a little confused.

#9

starting position would be wherever the beam starts, for example character.RightHand or parts of a tool, such as the handle, and ending would be the player’s mouse position, such as

local mouse = game.Players.LocalPlayer:GetMouse()
local endingpos = mouse.hit.p

you can only get the mouse on the client, i suggest making the actual beam on server and creating the raycasts on the client.

#10 
task.wait(1)
local parameters = RaycastParams.new()
parameters.FilterDescendantInstances = {--thing not to be touched by beam, for example u could put player.Character here}
parameters.FilterType = Enum.RayCastFilterType.Blacklist
local startpos = game.Players.LocalPlayer.Character.RightHand
local endpos = game.Players.LocalPlayer:GetMouse().hit.p
local ray = workspace:RayCast(startpos, (endpos - startpos).Unit, parameters)
if ray then
     print(ray.Instance)
else
     print("Ray didnt hit anything")
end

final script

#11

Sorry for the probably stupid questions but where does the actual beam part come in?
And also it says in the console “‘FilterDescendantInstances’ is not a valid member of RaycastParams”

#12

There is a good article on the wiki that explains how to use raycasting, I highly recommend you check it out Raycasting | Roblox Creator Documentation

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