Blackboard

Blackboard is used to share information between multiple components in an Agent.

• It can be access from many places, such as Inputs, Input Normalizations, Target Filters, Actions.
• It contains a list of Variables and you can Read/Write to these Variables for any purpose.

Creating Variables¶

To create a new variable, you need to create a new class inherited from Variable<TValue>. For example:

public class FloatVariable : Variable<float>
{
    public FloatVariable()
    {
    }

    public FloatVariable(float value) : base(value)
    {
    }

    public static implicit operator FloatVariable(float value)
    {
        return new FloatVariable { Value = value };
    }
}

Then you can add this variable to your agent’s blackboard by going to the Blackboard Tab, select the variable type, give it a name and then click the Create button:

Referencing Variables¶

And to reference the variable you just created, you need to declare a VariableReference<Type>. For example:

• Action:
  

  public class Wait : ActionTask
  {
      private float elapsedTime;
      public VariableReference<float> WaitTime = 1.0f;
  
      protected override void OnStart()
      {
          elapsedTime = 0;
      }
  
      protected override Status OnUpdate(float deltaTime)
      {
          elapsedTime += deltaTime;
  
          if (elapsedTime > WaitTime) return Status.Success;
          return Status.Running;
      }
  }
  

• Input Normalization:
  

  public class DivideByMaxValueNormalizationFloat : DivideByMaxValueNormalization<float>
  {
      public VariableReference<TValue> MaxValue;
  
      protected override float OnCalculateNormalizedInput(float rawInput, InputContext context)
      {
          if (MaxValue == 0.0f) return 0.0f;
          return rawInput / MaxValue;
      }
  }
  

Then select the variable from this dropdown menu in the Editor:

Built-in Variables¶

Currently, we provides these built-in variables:

• Float
• Double
• Int
• Long
• Bool
• String
• Vector2
• Vector2Int
• Vector3
• Vector3Int
• Color
• GameObject
• Transform