HitboxCaster

-- Made by St_vnC
-- St_vn#3931
-- Latest update : 12/11/2020

--[[
API :
  ** IMPORTANT : Requiring the module returns the constructor function **

  Constructor function : Parameter(Part), creates a new hitbox with the attachments in the specified part

  Hitbox:Cast(Filter) : Raycasts continuously for the hitbox with a specified filter until Hitbox:Stop() is called, the parameters are Part, Model, Humanoid, The attachment's parent

  Hitbox:Stop() : Stop casting rays for this hitbox

  Hitbox:Remove() : Removes the hitbox and allows it to be garbage collected
]]

local createSignal = require(game.ReplicatedStorage.Modules.Util.ScriptSignalService) -- You could alternatively use BindableEvents but I'd rather not use instances. Signal Service : https://pastebin.com/P4C3X7KV
local Heartbeat = game:GetService("RunService").Heartbeat -- recommended to handle connection(s)/tasks procedurally

local hitbox = {}
hitbox.__index = hitbox

local hitboxes = {}
local active = {}

local zero = Vector3.new()
local whitelist = "DmgPoint"
local rayParams = RaycastParams.new()
rayParams.FilterType = Enum.RaycastFilterType.Blacklist

local function Callback()
    for myPart, info in pairs(active) do
        if info.Position - myPart.Position == zero then continue end

        for _, attachment in ipairs(info.Attachments) do
            rayParams.FilterDescendantsInstances = info.Filter

            local results = workspace:Raycast(attachment.WorldPosition, (myPart.Position - info.Position).Unit, rayParams)

            if results then
                local part = results.Instance
                local model = part:FindFirstAncestorWhichIsA("Model")
                local human = model and model:FindFirstChildWhichIsA("Humanoid")

                table.insert(info.Filter, model)

                if human then
                    info.Signal:Fire(part, model, human, myPart)
                end
            end
        end

        info.Position = myPart.Position
    end
end

function hitbox:Cast(Filter)
    self.Position = self.Part.Position
    self.Filter = Filter

    active[self.Part] = self
end

function hitbox:Stop()
    local Filter = self.Filter
    self.Position = nil

    for _ = 1, #Filter or 1 do
        table.remove(Filter)
    end

    activeCount -= 1
    active[self.Part] = nil
end

function hitbox:Remove()
    local attachments = self.Attachments

    self:Stop()
    self.Signal:Destroy()
    hitboxes[self.Part] = nil
    self.Part = nil

    for _ = 1, #attachments do
        table.remove(attachments)
    end
end

return function(part)
    if hitboxes[part] then
        return hitboxes[part]
    else
        local attachments = {}

        for _, attachment in ipairs(part:GetChildren()) do
            if not attachment:IsA("Attachment") then continue end
            attachments[#attachments + 1] = attachment
        end

        hitboxes[part] = setmetatable({
            Part = part,
            Attachments = attachments,
            Signal = createSignal()
        }, hitbox)

        return hitboxes[part]
    end
end