OBS Studio script to turn child items of a scene on/off over time

animate-robots.lua

-- https://obsproject.com/docs/scripting.html
local obs = obslua

-- Globals

local function log(name, msg)
  if msg ~= nil then
    msg = " > " .. tostring(msg)
  else
    msg = ""
  end
  obs.script_log(obs.LOG_DEBUG, name .. msg)
end

-- source_handlers

local source_handlers = {}

local function activate(s, source, source_name, activated)
  s.source = source
  if s.activated == activated then
    return
  end
  s.activated = activated
  if activated then
    log("start", source_name)
    s.start()
    s.update()
    obs.timer_add(s.update, s.delay)
  else
    log("stop", source_name)
    obs.timer_remove(s.update)
  end
end

local function each_child(s, cb)
  local scene = obs.obs_scene_from_source(s.source)
  local items = obs.obs_scene_enum_items(scene)
  for i, item in pairs(items) do
    local item_source = obs.obs_sceneitem_get_source(item)
    local item_name = obs.obs_source_get_name(item_source)
    cb(item, item_name)
  end
end

local function add(name, cb)
  local s = {}
  s.source = nil
  s.activated = false
  s.activate = activate
  s.each_child = each_child
  source_handlers[name] = s
  cb(s)
end

-- Called when scenes become activated or deactivated
-- https://dev.to/talk2megooseman/zeal-stream-11-8-2019-learning-obs-lua-plugin-development-2nh8

local function activate_signal(calldata, activated)
  local source = obs.calldata_source(calldata, "source")
  if source ~= nil then
    local name = obs.obs_source_get_name(source)
    if (source_handlers[name]) then
      source_handlers[name]:activate(source, name, activated)
    end
  end
end

local function source_activate(calldata) activate_signal(calldata, true) end
local function source_deactivate(calldata) activate_signal(calldata, false) end

function script_load(settings)
  log("load")
  local sh = obs.obs_get_signal_handler()
  obs.signal_handler_connect(sh, "source_activate", source_activate)
  obs.signal_handler_connect(sh, "source_deactivate", source_deactivate)
end

-- Source handlers

function script_description()
  return "Animate robots"
end

add("Scene: Hypno Robots Wrapper", function(s)
  local step_index
  local count = 0
  local rl = "Robot Overlay Left"
  local rc = "Robot Overlay Center"
  local rr = "Robot Overlay Right"
  local ml = "Robot Overlay Left Dynamic Mask"
  local mc = "Robot Overlay Center Dynamic Mask"
  local mr = "Robot Overlay Right Dynamic Mask"
  local steps = {
    {count=100, rc},
    {count=100, mc},
    {count=100, ml, mc, mr},
    {count=100, ml, rc, mr},
    {count=100, ml, mc, mr},
    {count=100, mc},
  }

  s.delay = 200
  s.start = function()
    count = 0
    step_index = 0
  end
  s.update = function()
    count = count - 1
    if count > 0 then
      return
    end

    step_index = step_index + 1
    if step_index > table.getn(steps) then
      step_index = 1
    end

    local step = steps[step_index]
    count = step.count
    local stepMap = {}
    for i, name in pairs(step) do
      stepMap[name] = true
    end

    s:each_child(function(item, item_name)
      obs.obs_sceneitem_set_visible(item, stepMap[item_name] or false)
    end)
  end
end)