The brain's Lua

Steady Commander

Steady Commander is the made-up brain in brains/examples/steady-commander. The two files below are copied as they are written. works-with is a quoted star, so the package fits any mod and the base game. The script returns a table of hooks. Name that table something other than brain: a file that starts local brain shadows the global the profile installs. fits returns true. save returns how many squads have been sent. The attack choice is soon, steady or late.

# SPDX-FileCopyrightText: The Open Annihilation Authors; see COPYRIGHT
# SPDX-License-Identifier: GPL-3.0-only

oabrain: 1
id: steady-commander
name: Steady Commander
version: "1.0"
author:
  name: Ridge Workshop
description: "Builds a little economy, then a factory, and sends a squad when it is ready."
tags:
  - economy
  - teaching
works-with:
  - "*"
levels:
  - id: easy
    name: Easy
    difficulty: easy
  - id: medium
    name: Medium
    difficulty: medium
  - id: hard
    name: Hard
    difficulty: hard
options:
  attack:
    type: choice
    label: "How soon to attack"
    values: ["soon", "steady", "late"]
    default: "steady"
    labels: ["Soon", "Steady", "Late"]
entry: brain.lua

-- SPDX-FileCopyrightText: The Open Annihilation Authors; see COPYRIGHT
-- SPDX-License-Identifier: GPL-3.0-only

-- Economy, then one land factory. Combat units gather until the attack
-- option's count is met, then go to the nearest enemy in sight.
-- save() keeps how many squads have been sent.

local hooks = {}
local sent, armed = 0, false
local commander, metal_type, energy_type, factory_type, combat_type
local metal_done, energy_done, factory_ordered = 0, 0, false
local factories, squad, sent_ids = {}, {}, {}
local ready = false

local function real_of(record, key)
    local value = record[key]
    if type(value) == "userdata" and type(value.tonumber) == "function" then
        return value:tonumber()
    end
    return type(value) == "number" and value or 0
end

local function positive(record, key)
    return real_of(record, key) > 0
end

local function words(record)
    local found, list = {}, record.category
    if type(list) ~= "table" then return found end
    for index = 1, #list do found[list[index]] = true end
    return found
end

-- A category the commander lacks, or no categories, so a copy is skipped.
local function labelled(record, commander_words)
    local any, fresh = false, false
    for word in pairs(words(record)) do
        any, fresh = true, fresh or commander_words[word] ~= true
    end
    return fresh or not any
end

local function land(record)
    return real_of(record, "minwaterdepth") <= 0
end

local function land_combat(record)
    return record.canmove == true and record.canattack == true and record.builder ~= true
        and record.canfly ~= true and land(record)
end

local function energy_record(record)
    return positive(record, "energymake") or positive(record, "makesmetal")
        or positive(record, "windgenerator") or positive(record, "tidalgenerator")
end

local function pick(list)
    if #list == 0 then return nil end
    return list[brain.random(#list)]
end

local function classify(list, commander_words)
    local metals, energies, plants = {}, {}, {}
    for index = 1, #list do
        local record = list[index]
        if record.commander ~= true and labelled(record, commander_words) then
            if positive(record, "extractsmetal") and land(record) then
                metals[#metals + 1] = record
            elseif energy_record(record) and land(record) then
                energies[#energies + 1] = record
            elseif record.builder == true and record.bmcode == 0 and land(record) then
                local built, fights = game.build_list(record), {}
                if type(built) == "table" then
                    for slot = 1, #built do
                        if land_combat(built[slot]) then fights[#fights + 1] = built[slot] end
                    end
                end
                local fight = pick(fights)
                if fight ~= nil then plants[#plants + 1] = { plant = record, unit = fight } end
            end
        end
    end
    return metals, energies, plants
end

local function squad_size()
    if me.options.attack == "soon" then return 4 end
    if me.options.attack == "late" then return 12 end
    return 8
end

local function plan_counts()
    if me.difficulty == "easy" then return 1, 1 end
    if me.difficulty == "hard" then return 2, 2 end
    return 2, 1
end

local function find_commander()
    local found = nil
    me:each_unit(function(unit)
        if found == nil and unit.type ~= nil and unit.type.commander == true then found = unit end
    end)
    return found
end

local function free(unit)
    local kind, _, idle = unit:head_order()
    return kind == nil or idle == true
end

local function place_build(builder, record)
    if builder.x == nil or builder.z == nil then return false end
    local facing = brain.random(4) - 1
    local _, _, x, z = brain.place(record, { x = builder.x, z = builder.z }, 200, facing)
    if x == nil then return false end
    return builder:build(record, { x = x, z = z }, facing) == true
end

local function note_finished(unit)
    local record = unit.type
    if record == nil or record.commander == true or unit.alive ~= true then return end
    if positive(record, "extractsmetal") then metal_done = metal_done + 1
    elseif energy_record(record) then energy_done = energy_done + 1
    elseif record.builder == true and record.bmcode == 0 then
        factories[unit.id], factory_ordered = unit, true
    elseif land_combat(record) and sent_ids[unit.id] ~= true then squad[unit.id] = unit
    end
end

local function nearest(origin)
    local best, best_distance
    for index = 1, #me.seen do
        local unit = me.seen[index]
        if unit.alive == true and unit.owner ~= me.player and me:allied(unit.owner) ~= true then
            local distance = brain.distance(origin, unit)
            if distance ~= nil and (best_distance == nil or distance < best_distance) then
                best, best_distance = unit, distance
            end
        end
    end
    return best
end

local function count_squad()
    local count = 0
    for _ in pairs(squad) do count = count + 1 end
    return count
end

local function try_send()
    if count_squad() < squad_size() then return end
    local origin = (commander ~= nil and commander.alive == true) and commander or nil
    if origin == nil then
        for _, unit in pairs(squad) do origin = unit break end
    end
    local target = origin ~= nil and nearest(origin) or nil
    if target == nil then return end
    for id, unit in pairs(squad) do
        if unit.alive == true then unit:attack(target) end
        sent_ids[id] = true
    end
    squad, sent = {}, sent + 1
end

local function prepare()
    if ready then return end
    if commander == nil or commander.alive ~= true then commander = find_commander() end
    if commander == nil or commander.type == nil then return end
    local list = game.build_list(commander.type)
    if type(list) ~= "table" or #list == 0 then return end
    local metals, energies, plants = classify(list, words(commander.type))
    metal_type, energy_type = pick(metals), pick(energies)
    local plant = pick(plants)
    if plant ~= nil then factory_type, combat_type = plant.plant, plant.unit end
    ready = metal_type ~= nil or energy_type ~= nil or factory_type ~= nil
end

local function build_next()
    prepare()
    if commander == nil or commander.alive ~= true then commander = find_commander() end
    if commander == nil or not free(commander) then return end
    local metal_need, energy_need = plan_counts()
    if metal_type ~= nil and metal_done < metal_need then
        if place_build(commander, metal_type) then return end
    end
    if energy_type ~= nil and energy_done < energy_need then
        if place_build(commander, energy_type) then return end
    end
    if factory_type ~= nil and not factory_ordered then
        if place_build(commander, factory_type) then factory_ordered = true end
    end
end

local function queue_plants()
    if combat_type == nil then return end
    for _, plant in pairs(factories) do
        if plant.alive == true and free(plant) then plant:queue(combat_type) end
    end
end

local function step()
    build_next()
    queue_plants()
    try_send()
end

function hooks.fits() return true end

function hooks.start(_, _, saved)
    sent = type(saved) == "table" and type(saved.sent) == "number" and saved.sent or 0
    metal_done, energy_done, factory_ordered, factories, squad = 0, 0, false, {}, {}
    metal_type, energy_type, factory_type, combat_type = nil, nil, nil, nil
    ready, commander = false, find_commander()
    prepare()
    me:each_unit(function(unit)
        if unit.finished == true then note_finished(unit) end
    end)
    if not armed then
        brain.every(30, step)
        armed = true
    end
end

function hooks.onUnitFinished(unit)
    note_finished(unit)
    try_send()
end

function hooks.onUnitIdle(unit)
    local record = unit.type
    if record == nil then return end
    if record.commander == true then
        commander = unit
        build_next()
    elseif record.builder == true and record.bmcode == 0 then
        factories[unit.id] = unit
        queue_plants()
    end
end

function hooks.save() return { sent = sent } end

return hooks

Hooks

The entry returns one table. A missing function is skipped. fits and start run before the first tick. One turn then delivers, in this order: queued unit events, radar and sonar lost then gained, alliance changes, defeats, chat, timers, and onTick. The first turn stores the alliances and who is participating and reports none of those changes. At most 65,536 events are kept for one turn. Past that, the event is dropped.

What a brain may know

game is one read-only table for the life of the seat. fits and start receive that same table. The standard names every field. These are the groups.

What a brain may do

A unit handle takes the orders a player can give. Each call reaches the match at once. The order runs in the next tick. A refusal returns false. The first failing check is dead, not_own, over_limit (the turn has already passed 4,096 orders to the match), not_seen, or not_buildable. A match refusal counts as by_engine.

Numbers

fixed counts 65536ths. Axes are x east, z south and y up. An angle is an integer, 65536 to a full turn. f32 holds one binary32 value, the width of a player's resources. geometry.direction, geometry.planar_length, geometry.length, geometry.scale, geometry.sine_scaled and geometry.cosine_scaled are the engine's own heading, distances and scaled sine and cosine.

Random draws

brain.random(n) returns an integer from 1 to n, from the brain's own stream. That stream is seeded from the match, the player and the brain's id and version. Draws from it do not advance the match's shared stream. Replacing math.random does not change brain.random.

brain.shared_random draws the match's shared stream, and brain.setup_random draws a copy taken at the seat's built-in set-up. The standard installs them for Classic, and says where a shadow run has them. Any other brain has neither. brain.float_heap_order sorts integer distances, nearest first, and is installed for every seat.

Timers

brain.after(ticks, fn) runs fn once, that many turns later. brain.every(ticks, fn) runs then, and again every ticks turns after the due tick it just met. ticks is an integer from 1 to 2147483647. Each call returns an id. Ids start at 1 and only grow. brain.cancel(id) returns true when it removed a waiting timer. A brain may keep 1024 timers waiting. Due timers run after chat and before onTick. An error inside a timer stops the seat the way a hook error does.

Chat

onChat runs once per line since the last turn. A missing onChat is skipped, and the line is still consumed. brain.say(text, to) hands one line to the match at once. to is all (the default), allies, enemies, or a player index from 0 to 9. The call returns true when the line was queued. It does not pace itself. The match does, at 30 ticks between lines a computer seat says. A refusal is not_a_seat, empty, command, too_soon, no_target or no_chat.