[Rseding] [for 0.16] Item used to build an entity doesn't respect order

[mickael9]

This bug is about the way the game selects which item is needed for building a specific entity (eg, when placing a ghost).

I already discussed this with Rseding91 on #factorio and was told that the game used the first item in the prototype sort order (group, subgroup, order key).

Unfortunately, this isn't how the game does it actually. I've done a bit of research and made a few hypothesis on how the items are actually sorted:

• By order of appearance in data.raw (unlikely since data.raw is indexed by prototype type)
• By item type and order of appearance
• By item type and name
• By item name

I set up a test data.lua that creates a few items so that the result will tell us which hypothesis seems to be the good one:

data.lua

Code: Select all

require 'util'

local chest_prototype = table.deepcopy(data.raw.container['wooden-chest'])

chest_prototype.name = 'dummy-entity'
chest_prototype.minable.result = 'item-5'

--[[
We want robots to build the dummy-entity with a item-5

In theory, the robot should use the first item according to sorted prototypes order
that has a place_result matching the wanted entity

However, this doesn't seem to be what is actually happening

Here is the result of sorting the items using other sort criteria:

By order of appearance in data.raw: item-{2 4 3 5 1}
By item name: item-{1 2 3 4 5}
By item type and name: item-{3 4 1 2 5}
By item type and order of appearance: item-{4 3 2 5 1}
By order key: item-{5 3 1 4 2}

--]]


local function make(name, type, order)
    return {
        name = 'item-' .. name,
        type = type,
        flags = {},
        order = order,
        icon = '__base__/graphics/icons/signal/signal_' .. name .. '.png',
        stack_size = 1,
        place_result = 'dummy-entity',
    }
end

data:extend{
    chest_prototype,

    make('2', 'item-with-tags', '4'),
    make('4', 'item',           '3'),
    make('3', 'item',           '1'),
    make('5', 'item-with-tags', '0'),
    make('1', 'item-with-tags', '2'),
}

Using this code, we try to ghost-build a dummy-entity:

Code: Select all

/c game.player.surface.create_entity{name = 'entity-ghost', inner_name = 'dummy-entity', position = { game.player.position.x, game.player.position.y - 1 }, force = game.forces.player }

And we get this:

alert.png (29.93 KiB) Viewed 2069 times

The expected result would be a "5" icon (for item-5)
So it would seem that the game actually uses the first item in ascending name order which is quite inconvenient if you want to control which item gets used.

[Rseding91]

Thanks for the report. I plan on changing it but not at this stage for 0.15 I'll do it for 0.16.

[kovarex]

What is the reason to build one entity with two items anyway. What if we just disallowed it completely? It would definitely solve this bug wouldn't it?

[mickael9]

If you have items that have different "variants" (different item name/type) then it avoids creating dummy entities to match each variant of the item.
You can also control which item a construction robot will use to build an entity, while allowing the player to use a different item to place it.

For instance, my portable chests mod features portable chest items that can be placed as containers (entities), but I have two variants of the chest item: an "empty" variant (which is just a item-with-tags) and a normal variant (item-with-inventory).

The idea here is that the player should be able to build the container entity using the item-with-inventory while construction robots can only use the item-with-tags variant. If I only had one variant (item-with-inventory), the robots would take any item, even if it has items in its inventory, and use that to build a newly created ghost, loosing all items in the item's inventory.