LuaBurner::current_usage

[LuziferSenpai]

It would be very awesome, if the burner would expose the current_usage.

Currently we would need to do some math to get that number:

Code: Select all

--[[
Current fuel consumption of a train's locomotives.

Math (Factorio wiki, "Locomotive" → Speed calculations), per tick:

    v1 = max(0, |v| - friction / weight)            -- friction
    v2 = v1 + a_full                                -- engines at full power
    v3 = v2 * r                                     -- air resistance
    v  = min(v3, max_speed)                         -- top speed cap

    a_full = (sum of pulling locomotives' max usage in J/tick / 1000) * fuel_acceleration_multiplier / weight
    r      = 1 - front_air_resistance * 1000 / weight

Locomotives only burn the acceleration they actually use:

    a_used      = min(a_full, max_speed / r - v1)
    fraction    = clamp(a_used / a_full, 0, 1)
    consumption = max_usage * fraction              -- per locomotive, J/tick

Below top speed fraction = 1 (full power). At top speed it drops to
    (v * (1 - r) / r + friction / weight) / a_full

Assumes the train is throttling (automatic train on its path, or a player
holding accelerate). Braking, coasting and standing still burn 0.
]]
--- @param train LuaTrain
--- @return table<uint64, double> consumption J/tick per locomotive, keyed by unit_number (0 for locomotives that are not pulling)
--- @return double total J/tick of the whole train
local function get_current_consumption(train)
    local consumption = {}
    local total = 0
    local speed = train.speed
    local forward = speed >= 0
    local movers = forward and train.locomotives.front_movers or train.locomotives.back_movers
    local idle = forward and train.locomotives.back_movers or train.locomotives.front_movers
    local front_stock = forward and train.front_stock or train.back_stock
    local max_speed = forward and train.max_forward_speed or train.max_backward_speed
    local weight = train.weight

    for _, locomotive in pairs(idle) do
        consumption[locomotive.unit_number] = 0
    end

    local friction = 0
    for _, carriage in pairs(train.carriages) do
        friction = friction + carriage.prototype.friction_force
    end

    local power = 0
    local acceleration_multiplier
    for _, locomotive in pairs(movers) do
        power = power + locomotive.prototype.get_max_energy_usage(locomotive.quality)

        local burning = locomotive.burner.currently_burning
        if burning then acceleration_multiplier = burning.name.fuel_acceleration_multiplier end
    end

    local fraction = 0
    if power > 0 and acceleration_multiplier then
        local r = 1 - front_stock.prototype.air_resistance * 1000 / weight
        local a_full = power / 1000 * acceleration_multiplier / weight
        local v1 = math.max(0, math.abs(speed) - friction / weight)
        local a_used = math.min(a_full, max_speed / r - v1)

        fraction = math.max(0, math.min(1, a_used / a_full))
    end

    for _, locomotive in pairs(movers) do
        local usage = locomotive.prototype.get_max_energy_usage(locomotive.quality) * fraction

        consumption[locomotive.unit_number] = usage
        total = total + usage
    end

    return consumption, total
end

That would give us more precise options to maybe power LuaBurner entities via onTick or display the usage somewhere.
My personal use case would be improving my mod https://mods.factorio.com/mod/Electronic_Locomotives.

Greetz,

Luzifer