A script for Roblox games that spawns parts within regions defined by `Start` and `End` controlpoints

RobloxRegionSpawner.lua

local manager = script.Parent

-- helper function for colliding with humanoids
local function TouchedHumanoid(f)
  return function(collider) 
    local parent = collider.Parent
    if parent:FindFirstChildWhichIsA("Humanoid") then
      f(parent)			
    end
  end
end

-- track button state
local enabled = false
local button = manager.ButtonToggle
local pause = false
local function UpdateButtonState()
  if enabled then
    print("ENABLE: " .. manager.Name)
    button.BrickColor = BrickColor.new("Dark green")
  else
    print("DISABLE: " .. manager.Name)
    button.BrickColor = BrickColor.new("Tr. Red")
  end
end
UpdateButtonState()
button.Touched:Connect(TouchedHumanoid(function(player)
  if pause then
    return
  end
  pause = true
  enabled = not enabled
  UpdateButtonState()
  wait(1) -- second
  pause = false
end))

-- loop through all regions we need to spawn particles for
local regions = { }
local mag_total = 0
for i, model in ipairs(manager.Regions:GetChildren()) do
  -- set each region to be invisible to players
  for _, child in ipairs(model:GetChildren()) do
    child.CanCollide = false
    child.Anchored = true
    child.CanTouch = false
    child.Transparency = 1.0
  end
  -- calculate region data
  local pos_start = model.Start.Position
  local pos_end = model.End.Position
  local mag = (pos_end - pos_start).Magnitude
  regions[i] = {
    Part = model,
    MinPos = Vector3.new(
      math.min(pos_start.X, pos_end.X),
      math.min(pos_start.Y, pos_end.Y),
      math.min(pos_start.Z, pos_end.Z)),
    MaxPos = Vector3.new(
      math.max(pos_start.X, pos_end.X),
      math.max(pos_start.Y, pos_end.Y),
      math.max(pos_start.Z, pos_end.Z)),
    Probability = mag,
  }
  mag_total = mag_total + mag
end
if mag_total > 0 then
  -- normalise probabilities
  for _, region in ipairs(regions) do
    region.Probability = region.Probability / mag_total 
  end
end

-- handle the creation of new parts
local part_count = 0
local part_limit = 100
local function SpawnRandomParts()
  if part_count >= part_limit then
    return
  end
  for i, region in ipairs(regions) do
    if math.random() > region.Probability then
      continue
    end
    -- spawn a new part within this region
    part_count = part_count + 1
    local random_pos = Vector3.new(
      math.random(region.MinPos.X, region.MaxPos.X),
      math.max(region.MinPos.Y, region.MaxPos.Y),
      math.random(region.MinPos.Z, region.MaxPos.Z))
    local new_part = Instance.new("Part")
    new_part.Parent = region.Part
    new_part.Position = random_pos
    new_part.Size = Vector3.new(1, 1, 1)
    new_part.Shape = "Ball"
    new_part.Anchored = true
    -- delete the part if the player touches it
    new_part.Touched:Connect(TouchedHumanoid(function(player)
      part_count = part_count - 1
      new_part:Destroy()			
    end))
  end
end

-- spawn a service that creates parts periodically whilst active
local run_service = game:GetService("RunService")
local current_time = 0
local duration = 0.5 -- second
run_service.Heartbeat:Connect(function(delta_time)
  if not enabled then
    return
  end 
  current_time = current_time + delta_time
  if current_time >= duration then
    current_time = current_time - duration
    SpawnRandomParts()
  end
end)