how to make parts go invisible when they get hit by the ray and visible when they dont ?

the title explains it self, im making a top down rpg game, just like guest quest, i need help with something tho.

thats my code for now, its a local script inside of starter character scripts:

local rayDirection = Vector3.new(0,1,0)

local char = game.Players.LocalPlayer.Character

local RAY_LENGTH = 30


function findAllPartsOnRay(ray)
    local targets = {}
    repeat
        local target = game.Workspace:FindPartOnRayWithIgnoreList(ray, targets)
        if target then
            table.insert(targets, target)
        end
    until not target
    return targets
end

game:GetService("RunService").Heartbeat:Connect(function()
    local ray = Ray.new(char.Head.Position,rayDirection * RAY_LENGTH)


    local parts = findAllPartsOnRay(ray)
    if parts then
        for index, value in ipairs(parts) do
            value.Transparency = 0.7
            wait()
            value.Transparency = 0
        end
    end
end)

i mean it works but it keeps blinking, so i want to make that the part becomes visible only when the ray its not hitting it