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Gameplay · guide

Authoring a loot table

An editable model over the definition, a flattened outline for a tree view, and a drop simulator that runs the shipped evaluator.

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What it is#

Three things a loot-table editor needs and one of them is the interesting one.

  • LootTableModel — the definition, edited in place, with every gesture as one operation and one
  • Changed, plus a Validate that says everything the content build would refuse.
  • LootOutline — the tree flattened depth-first, with each weighted row's share of its table's pick.
  • LootSimulator — ten thousand kills through the shipped LootEvaluator, reported as rates.

What it is for#

Balancing a table without shipping it. A designer changes a weight and sees what it did, in the same arithmetic the realm will run — which is doc 28's actual requirement: *"simulated in the editor with the real evaluator"*.

A simulator with its own arithmetic is a second set of odds, and the one a designer balances against is the one that is wrong. That is the whole argument for the evaluator being a library.

Using it#

Wrap the definition in a model, run the simulator after each edit, and draw the outline beside its results — the outline is what the table was *written* to do and the simulation is what it does, and a gap between them is a condition nobody accounted for.

⚠ A simulation starts from a fresh pity store. One that inherited a live player's bad luck would report a rate nobody else will ever see. It also means the simulator and a hand-written loop only agree if both are given a store: a pity row that drops consumes an extra draw from the stream.

⚠ EmptyEvents is the figure to look at first. A table whose weighted rows are all conditional drops nothing on an ordinary kill, and the authored file looks perfectly reasonable.

⚠ GuaranteeHeld is a bug report, not a balance figure. A drought longer than the pity policy's guarantee is a ramp that never starts or an evaluator that stopped honouring the policy.

⚠ A conditional row's share is true of no actual kill — it is computed as though every conditional row were present — so the row carries a Conditional flag and a view must show it.

⚠ Moving a row is a real edit. The evaluator runs independent rows in authored order, so reordering changes what every recorded event id produces. It is not a sort.

Examples#

Editing, validating, and previewing after each gesture:

csharp
using System.Collections.Generic;using Vixen.Editor.Gameplay.Loot;using Vixen.Gameplay;using Vixen.Gameplay.Items;using Vixen.Gameplay.Loot;static class Authoring {    public static LootSimulation Preview(        LootLibrary loot,        ItemLibrary items,        LootTableModel model,        DefId table    ) {        model.Edit(0, entry => entry.Weight = 4f);        // Everything the content build would refuse, attributed to a row so it can be highlighted.        IReadOnlyList<LootProblem> problems = model.Validate();        _ = problems;        // The same evaluator the realm runs, over a run somebody else can reproduce.        return LootSimulator.Run(loot, loot.Get(table), items, events: 10000, firstEventId: 1);    }}

Reading the result the way a table view would:

csharp
using System;using Vixen.Editor.Gameplay.Loot;static class Report {    public static void Write(LootSimulation simulation, Action<string> line) {        line($"{simulation.EmptyEvents} of {simulation.Events} kills dropped nothing");        foreach (var item in simulation.Items) {            line($"{item.Name}: {item.RateOver(simulation.Events):P2} of kills, {item.PerEvent(simulation.Events):F2} each");        }        if (simulation.Pity is { } pity && !pity.GuaranteeHeld) {            line($"a drought of {pity.LongestDrought} exceeded the guarantee of {pity.Guarantee}");        }    }}

Drawing the tree beside it:

csharp
using System;using Vixen.Editor.Gameplay.Loot;using Vixen.Gameplay.Items;using Vixen.Gameplay.Loot;static class Tree {    public static void Write(LootLibrary loot, LootTable table, ItemLibrary items, Action<string> line) {        foreach (var row in LootOutline.Of(loot, table, items)) {            var share = row.Chance > 0f ? $"{row.Chance:P1} chance" : $"{row.Share:P1} of the pick";            line($"{new string(' ', row.Depth * 2)}{row.Label} — {share}{(row.Conditional ? " (conditional)" : "")}");        }    }}

See also#

  • Loot tables — the evaluator this previews, and the rules it enforces.
  • Items — where the names in the report come from.
  • Gameplay randomness — why a simulation is reproducible at all.