View source for Regen

[[File:Regenbutton.png|thumb|150px|A typical regen button.]]
'''Regen''' (short for '''regeneration''') is a method of deleting and replacing a {{Class link|Model}} object or other given group of [[instance]]s with its copy (also known as the ''backup''). The given group is usually cloned right after its beginning of existence and stored as the backup. Regeneration is used to restore the group that may be damaged or lost, and can be done periodically or via a button (often a [[part]]), or both.

In [[script]]ing, regeneration is one of the most used examples due to its basic elements of performing operations on the [[engine]]'s data model. An example [[place]] is [[Community:Roblox/Classic: Crossroads|Crossroads]], where destructible buildings are regenerated every few minutes.

== Script ==
In order to regenerate a given group of instances, specifically a {{Class link|Model}} object, the copy of the instance has to be stored as soon as possible. Because the given instance may not exist the time the code is executed, {{Member link|Instance|WaitForChild}} is used to yield the code until the instance with the given name is loaded under its [[parent]]. After it loads, the code may yield for a short period of time to allow the instance to fully load. The instance itself is then stored in the [[variable]] "model", which is used to later destroy the instance for regeneration. The code clones ({{Member link|Instance|Clone}}) the instance and stores the copy in the [[variable]] "backup".

The regen [[function]] is defined with three statements. First, it destroys ({{Member link|Instance|Destroy}}) the instance stored in the variable "model". Then, it clones the instance stored in the variable "backup" and assigns it to the variable "model", which will later be destroyed when the function is called again. The copy is then parented to its original parent. This function is called every five minutes later in the example.
:<syntaxhighlight lang="lua">
local model = workspace:WaitForChild("Model")
task.wait()
local backup = model:Clone()

local function regen()
    model:Destroy()
    model = backup:Clone()
    model.Parent = workspace
end

while task.wait(300) do
    regen()
end
</syntaxhighlight>

=== Messages ===
In legacy scripts, regen scripts often use a {{Class link|Message}} object to tell visitors that something is regenerating, and adds a delay before the regeneration.
:<syntaxhighlight lang="lua">
local model = workspace:WaitForChild("Model")
task.wait()
local backup = model:Clone()

local message = Instance.new("Message")
message.Text = "Regenerating model..."

local function regen()
    message.Parent = workspace
    
    model:Destroy()
    
    task.wait(4)
    
    model = backup:Clone()
    model.Parent = workspace
    
    message.Parent = nil
end

while task.wait(300) do
    regen()
end
</syntaxhighlight>

=== Surface welds ===
In legacy scripts where parts are welded via [[surface]]s, {{Member link|BasePart|MakeJoints}} or {{Member link|Model|MakeJoints}} is used to prevent the clone of the backup from falling apart after being parented.
:<syntaxhighlight lang="lua">
-- ...
local function regen()
    message.Parent = workspace
    
    model:Destroy()
    
    task.wait(4)
    
    model = backup:Clone()
    model.Parent = workspace
    model:MakeJoints() -- makes joints
    
    message.Parent = nil
end
-- ...
</syntaxhighlight>

=== Button ===
A regen script can be associated with a button (a part) by parenting to it and connecting the {{Member link|BasePart|Touched}} event to the regen function. Regen scripts may implement checks before calling the regen function, such as finding a {{Class link|Humanoid}} object to see if it is a [[character]] that is touching the button. This is done usually in another function. 

To prevent the regen from being activated too many times, a debouncer is implemented by using an "enabled" variable which prevents the function from being called when set to false, often associated with the part's color which turns black when set to false and turns to the original color when set to true. The variable is set to false at the beginning of the function and has a delay before being set to true again.

:<syntaxhighlight lang="lua">
local button = script.Parent
local enabled = true
local color = button.BrickColor

local model = workspace:WaitForChild("Model")
task.wait()
local backup = model:Clone()

local message = Instance.new("Message")
message.Text = "Regenerating model..."

local function regen()
    enabled = false
    button.BrickColor = BrickColor.Black()
    
    message.Parent = workspace
    
    model:Destroy()
    
    task.wait(4)
    
    model = backup:Clone()
    model.Parent = workspace
    model:MakeJoints()
    
    message.Parent = nil
    
    task.wait(30)
    
    enabled = true
    button.BrickColor = color
end

local function onTouched(hit)
    if enabled and hit.Parent:FindFirstChild("Humanoid") then
        regen()
    end
end

button.Touched:Connect(onTouched)
</syntaxhighlight>

[[Category:Game development]]
[[Category:Scripting]]