Defining an encounter starts with its RoomType, which determines where it can spawn, and if it is a Boss room, that it also requires a special run history icon.

Override IsValidForAct to determine where an encounter can spawn. Filtering to a specific act or act number is recommended.

If you are making a custom act, you can add the encounter to the act either through IsValidForAct, or return false in IsValidForAct and manually add it to the act’s GenerateAllEncounters method.

Encounters have a list of slots. These should correspond to named nodes in the encounter scene.

The encounter scene is a 1920x1080 Control with Full Rect anchors, and Marker2D children for enemy positions. The names of these markers (corresponding to Slots) can be used with CreatureCmd.Add when spawning additional enemies. The game will place enemies in default positions if an encounter scene is not provided.

AllPossibleMonsters should be a simple list of all enemies that appear in the fight. Repeating duplicates is not necessary.

GenerateMonsters is used to generate the actual monsters for a fight, and should call ToMutable on the monsters generated. Each monster is paired with an optional string key (null to omit) which sets its spawning Slot. If the enemies in the fight are randomized, that should be done in this method using the encounter’s Rng object.

For CustomEncounterBackground, use BackgroundAssets if reusing a basegame set of assets, or a new CustomBackgroundAssets if using custom file paths.

See comments in class for additional documentation of methods that can be overridden.

public class HellEncounter : CustomEncounterModel
{
    public HellEncounter() : base(RoomType.Boss)
    {
    }

    public override IReadOnlyList<string> Slots =>
    [
        "queen",
        "amalgam",
        "doormaker",
        "test_subject"
    ];

    public override string? CustomScenePath => "res://mod/scenes/HellEncounter.tscn";

    //Visuals and camera position of combat scene; all optional
    public override BackgroundAssets? CustomEncounterBackground(ActModel parentAct, Rng rng)
    {
        return new BackgroundAssets(ModelDb.Encounter<QueenBoss>().Id.Entry.ToLowerInvariant(), Rng);
    }
    public override string CustomBgm => "event:/music/act3_boss_queen";
    public override float GetCameraScaling() => 0.85f;
    public override Vector2 GetCameraOffset() => Vector2.Down * 60f;

    protected override IReadOnlyList<(MonsterModel, string?)> GenerateMonsters() =>
    [
        (ModelDb.Monster<TorchHeadAmalgam>().ToMutable(), "amalgam"),
        (ModelDb.Monster<Queen>().ToMutable(), "queen"),
        (ModelDb.Monster<Doormaker>().ToMutable(), "doormaker"),
        (ModelDb.Monster<TestSubject>().ToMutable(), "test_subject")
    ];

    public override IEnumerable<MonsterModel> AllPossibleMonsters => 
    [
        ModelDb.Monster<Queen>(),
        ModelDb.Monster<TorchHeadAmalgam>(),
        ModelDb.Monster<Doormaker>(),
        ModelDb.Monster<TestSubject>()
    ];

    //An image must be set if making a boss. Otherwise, it will attempt to load a boss-specific image using the encounter name from basegame resources and fail.
    public override string? CustomRunHistoryIconOutlinePath => ImageHelper.GetImagePath($"ui/run_history/{ModelDb.Encounter<QueenBoss>().Id.Entry.ToLowerInvariant()}.png");
    public override string? CustomRunHistoryIconPath => ImageHelper.GetImagePath($"ui/run_history/{ModelDb.Encounter<QueenBoss>().Id.Entry.ToLowerInvariant()}_outline.png");

    public override bool IsValidForAct(ActModel act)
    {
        return act.ActNumber() == 3;
    }
}