SetNet.BehaviorTree 1.2.0

SetNet.BehaviorTree

A small generic behavior tree for SetNet AI.

Assemble a tree from Sequence / Selector / Parallel composites, Inverter / Succeeder / Repeat / Cooldown decorators, and Do / Condition / Wait leaves with a fluent builder, then Tick(ctx, dtMs) it each frame over your own context type. Nodes return BtStatus.Success / Failure / Running, and Running leaves are resumed on the next tick. Engine-agnostic and free of any wire protocol — wrap one in an IMobBrain for mob AI, or use it anywhere.

// A goblin: attack if in range, else chase the target, else idle.
var tree = BehaviorTree<Mob>.Build()
    .Selector()
        .Sequence()
            .Condition(m => m.HasTarget && m.InAttackRange)
            .Cooldown(1500)                         // don't swing more than once per 1.5s
                .Do(m => m.Attack(m.Target))
            .End()
        .End()
        .Sequence()
            .Condition(m => m.HasTarget)
            .Do((m, dt) => m.MoveToward(m.Target) ? BtStatus.Running : BtStatus.Success)
        .End()
        .Do(m => m.Idle())                          // fallback leaf
    .End()
    .Create();

// each server tick:
var status = tree.Tick(mob, dtMs);

Concepts

• Composites open with Sequence() / Selector() / Parallel() and close with End(). Sequence is AND (fails on the first failure), Selector is OR (succeeds on the first success), Parallel ticks every child each frame.
• Decorators wrap exactly one node: Inverter() swaps Success/Failure, Succeeder() forces Success, Repeat(count) loops a child (count ≤ 0 = forever), Cooldown(ms) blocks re-running a child until the timer elapses.
• Leaves: Do(Func<TContext, float, BtStatus>) for a full action, Do(Action<TContext>) for a fire-and-succeed side effect, Condition(pred) for a boolean Success/Failure gate, Wait(ms) to stay Running for a duration. Node(...) attaches an already-built BtNode<TContext>.
• Ticking: Tick(ctx, dtMs) runs one pass and returns a BtStatus; Reset() clears every node's in-progress state. Sequence/Selector remember the child that was Running and resume there next tick.

Notes

• Pure library, no wire protocol. The tree runs wherever you tick it — typically server-side inside an IMobBrain, but it has no networking dependency beyond referencing SetNet.
• Actions and conditions are your delegates over TContext, so one built tree can drive many entities, each with its own context instance.
• Prefer a simpler shape? Reach for SetNet.StateMachine when a handful of states and transitions is enough.

License

MIT