EnemyAPI

An API for easily modifying the behavior of enemies.

To use this API, simply add these cs files to your project.

• OverrideBehavior.cs
• Tools.cs
• Hooks.cs

Prerequisites

.NET framework 2.0 or higher A reference to Mod The Gungeon, UnityEngine, and Enter The Gungeon dll's

Usage

The solution contains the project EnemyAPI.Tests, which shows you how to use EnemyAPI.

Here's the simple example described there:

public class TestOverrideBehavior : OverrideBehavior
{
    public override string OverrideAIActorGUID => "01972dee89fc4404a5c408d50007dad5"; // Replace the GUID with whatever enemy you want to modify. This GUID is for the bullet kin.
                                                                                      // You can find a full list of GUIDs at https://github.com/ModTheGungeon/ETGMod/blob/master/Assembly-CSharp.Base.mm/Content/gungeon_id_map/enemies.txt
    public override void DoOverride()
    {
        // In this method, you can do whatever you want with the enemy using the fields "actor", "healthHaver", "behaviorSpec", and "bulletBank".

        actor.MovementSpeed *= 2; // Doubles the enemy movement speed

        healthHaver.SetHealthMaximum(healthHaver.GetMaxHealth() * 0.5f); // Halves the enemy health

        // The BehaviorSpeculator is responsible for almost everything an enemy does, from shooting a gun to teleporting.
        // Tip: To debug an enemy's BehaviorSpeculator, you can uncomment the line below. This will print all the behavior information to the console.
        //Tools.DebugInformation(behaviorSpec);

        // For this first change, we're just going to increase the lead amount of the bullet kin's ShootGunBehavior so its shots fire like veteran kin.
        ShootGunBehavior shootGunBehavior = behaviorSpec.AttackBehaviors[0] as ShootGunBehavior; // Get the ShootGunBehavior, at index 0 of the AttackBehaviors list
        shootGunBehavior.LeadAmount = 0.62f;

        // Next, we're going to change another few things on the ShootGunBehavior so that it has a custom BulletScript.
        shootGunBehavior.WeaponType = WeaponType.BulletScript; // Makes it so the bullet kin will shoot our bullet script instead of his own gun shot.
        shootGunBehavior.BulletScript = new CustomBulletScriptSelector(typeof(TestBulletScript)); // Sets the bullet kin's bullet script to our custom bullet script.
    }

    public class TestBulletScript : Script // This BulletScript is just a modified version of the script BulletManShroomed, which you can find with dnSpy.
    {
        protected override IEnumerator Top() // This is just a simple example, but bullet scripts can do so much more.
        {
            base.Fire(new Direction(-40f, DirectionType.Aim, -1f), new Speed(6f, SpeedType.Absolute), null); // Shoot a bullet -40 degrees from the enemy aim angle, with a bullet speed of 6.
            base.Fire(new Direction(40f, DirectionType.Aim, -1f), new Speed(6f, SpeedType.Absolute), null); // Shoot a bullet 40 degrees from the enemy aim angle, with a bullet speed of 6.

            yield return Wait(20); // Wait for 20 frames

            base.Fire(new Direction(-20f, DirectionType.Aim, -1f), new Speed(9f, SpeedType.Absolute), null); // Shoot a bullet -20 degrees from the enemy aim angle, with a bullet speed of 9.
            base.Fire(new Direction(20f, DirectionType.Aim, -1f), new Speed(9f, SpeedType.Absolute), null); // Shoot a bullet 20 degrees from the enemy aim angle, with a bullet speed of 9.

            yield break;
        }
    }
}

Then, in your main module's Start method call this.

public override void Start()
{
    Hooks.Init(); // Calling this makes a hook that is responsible for actually changing enemy behaviors when they spawn.
    Tools.Init(); // Calling this adds all of the classes that extend OverrideBehavior to a list, so that they can actually be used.
    // Both methods are required to be called for the API to work.
}