Blackboard

Remarks

A read is a span slice and a write is a store. There is no hashing, no boxing and no allocation once the instance exists — a thousand agents on one layout is a thousand small arrays, sized at load and never resized.

⚠ A key is set or unset independently of its value. "Is Set" is the single commonest decorator in every behaviour-tree implementation there is, and Null, 0 and Zero are all legal values somebody means. So the set-ness is a bit in a mask beside the values, and Clear is a write like any other — it bumps the version and notifies.

Both a version and an observer list, because they answer different questions. Observers drive aborts: a decorator that must interrupt a running branch cannot poll. Versions drive everything that only wants to recompute when something moved — a service on an interval, a cached path, a scorer — and they let it answer "has this changed since I last looked" without keeping a copy of the value.

⚠ A version bumps only when the value actually changes. Writing the same number is not a change, and treating it as one would make every service that writes its result every tick abort every decorator observing it, for ever. That is the difference between an event-driven tree and a tree that ticks itself to death.

One agent owns one blackboard. That is what makes a tree step parallelisable over chunks — a step touches this agent's memory and this agent's board and nothing else. Data two agents share is a SharedBlackboard, which is a distinct type precisely so that sharing is a decision somebody made rather than something that happened.

Fields and properties (2)

• public BlackboardLayout Layout

  The shape this is an instance of.

• public uint Version

  How many times anything on this board has changed.

Methods (21)

• public Blackboard(BlackboardLayout layout)

  Creates an instance of a layout, with every key unset.

• public bool IsSet(BlackboardKey key)

  Whether a key has ever been written and not since cleared.

• public uint VersionOf(BlackboardKey key)

  How many times this key has changed.

• public bool Clear(BlackboardKey key)

  Unsets a key.

• public void Reset()

  Unsets every key.

• public bool GetBool(BlackboardKey key)

  Reads a boolean.

• public int GetInt(BlackboardKey key)

  Reads an integer.

• public float GetFloat(BlackboardKey key)

  Reads a float.

• public Vector3 GetVector3(BlackboardKey key)

  Reads a vector.

• public Entity GetEntity(BlackboardKey key)

  Reads an entity.

• public Symbol GetSymbol(BlackboardKey key)

  Reads a symbol.

• public bool SetBool(BlackboardKey key, bool value)

  Writes a boolean.

• public bool SetInt(BlackboardKey key, int value)

  Writes an integer.

• public bool SetFloat(BlackboardKey key, float value)

  Writes a float.

• public bool SetVector3(BlackboardKey key, Vector3 value)

  Writes a vector.

• public bool SetEntity(BlackboardKey key, Entity value)

  Writes an entity.

• public bool SetSymbol(BlackboardKey key, Symbol value)

  Writes a symbol.

• public BlackboardObserverHandle AddObserver(BlackboardKey key, IBlackboardObserver observer)

  Starts telling something when a key changes.

• public bool RemoveObserver(BlackboardObserverHandle handle)

  Stops telling it.

• public int ObserverCount(BlackboardKey key)

  How many observers are registered on a key.

• public Span<byte> AsBytes()

  The raw bytes, for a compiler, a serialiser or a test.

Used by (69, showing 40)

• AgentContextVixen.Ai
• AgentTargetVixen.Ai.Nodes
• AiSnapshotTestsVixen.Ai.Tests
• AiSnapshotsVixen.Ai
• AiSystemVixen.Ai
• AiSystemTestsVixen.Ai.Tests
• BehaviorContextVixen.Ai
• BehaviorTreeAbortOrderingTestsVixen.Ai.Tests
• BehaviorTreeAbortTestsVixen.Ai.Tests
• BehaviorTreeCompositeTestsVixen.Ai.Tests
• BehaviorTreeCostTestsVixen.Ai.Tests
• BehaviorTreeDecoratorTestsVixen.Ai.Tests
• BehaviorTreeDeterminismTestsVixen.Ai.Tests
• BehaviorTreeInstanceVixen.Ai
• BehaviorTreeServiceTestsVixen.Ai.Tests
• BehaviorTreeTaskTestsVixen.Ai.Tests
• BindingTestsVixen.Ai.Perception.Tests
• BlackboardDecoratorVixen.Ai
• BlackboardLayoutTestsVixen.Ai.Tests
• BlackboardTestsVixen.Ai.Tests
• BlackboardUtilityInputVixen.Ai
• BlackboardWorldSourceVixen.Ai
• BoardVixen.Ai.Nodes.Tests
• ClearBlackboardValueTaskVixen.Ai
• CompareEntriesDecoratorVixen.Ai
• ConeDecoratorVixen.Ai
• ConstantWorldSensorVixen.Ai
• CountingObserverVixen.Ai.Tests
• CountingSensorVixen.Ai.Tests
• DelegateObserverVixen.Ai.Tests
• DelegateWorldSensorVixen.Ai
• DistanceSensorVixen.Ai.Nodes
• DistanceUtilityInputVixen.Ai
• FocusTestsVixen.Ai.Nodes.Tests
• GoapDomainTestsVixen.Ai.Tests
• GoapHarnessVixen.Ai.Tests
• HarnessVixen.Ai.Tests
• IBlackboardBindingVixen.Ai.Perception
• IBlackboardObserverVixen.Ai
• IWorldSensorVixen.Ai