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EASY way to add AI in Unity 6 - Behavior Package Tutorial

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Introduction

Adding AI to your Unity games has often been a difficult task, either requiring the use of paid assets or the creation of custom AI solutions. However, with the introduction of the new officially supported and free Behavior package in Unity 6, this process has become significantly easier. In this tutorial, we'll explore how to utilize this powerful tool to create AI behaviors for your characters.

Getting Started with the Behavior Package

To begin, ensure you have a Unity 6 project set up. Open the Package Manager and search for the Behavior package to install it. Once installed, you can easily implement AI behaviors for your game characters.

Setting Up an NPC

For this tutorial, we will use a zombie NPC as our example. This NPC should already have a NavMesh Agent and an Animator component. To start adding AI behaviors, follow these steps:

  1. Add Component: Select your NPC, click on “Add Component,” and search for “Behavior Agent” to add the Behavior Agent component.
  2. Create a Behavior Graph: In the Project tab, right-click, select "Create" and then "Behavior," followed by "Behavior Graph." Name your graph (e.g., EnemyBehaviorGraph).
  3. Assign Graph to Agent: Select your NPC again, drag the newly created graph into the Behavior Agent component, and double-click it to open the graph window.

Defining Behavior in the Graph

In the graph window, you will see a Blackboard on the left side where you can add variables. For instance, create a list of Game Objects called PatrolPoints.

  • Create Patrol Node: Press the space bar to create a Patrol node. This node will make the NPC move using the NavMesh Agent.
  • Set Parameters: In the Inspector, you can define parameters such as speed and animator speed. Assign Self to the agent and drag the PatrolPoints from the Blackboard to the WayPoints in the node.
  • Connect Nodes: You will also find an OnStart node. Connect this to your Patrol node by dragging an arrow from one to the other.

Finalizing the Patrol Behavior

To complete the setup of your zombie’s patrol behavior:

  1. Assign Patrol Points: In the Inspector for your NPC, you will see the parameters from the Blackboard. Here, manually add the patrol points you previously prepared.
  2. Animator Setup: Ensure your Animator is correctly set up to blend between idle and walking animations based on the speed parameter.

Implementing Detection

To make your NPC more interactive by detecting the player, you can create a custom detector. Here’s how:

  1. Use Physics for Detection: Implement physics, such as Overlap Circle or Raycast, to detect the player within range.
  2. Add a Detector: In the Blackboard, create a new detector controller and name it TargetDetector.
  3. Create an Action Node: Right-click in the node space, select "Create New," and define an action named CheckDetector. Add logic to verify if TargetDetector has a target.
  4. Return Statuses: Use the OnStart or OnUpdate method to check for the current target and return success or failure based on whether the target is detected.

Creating Complex Behaviors

Utilize the behavior graph to create a simple sequence for your NPC to follow your player once detected:

  • Implementing Sequential Logic: Connect the node for checking if the target detector has a target to the action of moving the NPC to the detected target. The sequence will only proceed if the previous check is successful.
  • Behavior Types: Use running parallel sequences and explicit states such as Patrol, Chase, and Attack to define different behaviors for your NPC. For finite state machine setup, create an enumeration AIStates for easy state management.

Debugging and Testing

You can debug your NPC's behavior by using the debug feature available within the graph. This will help you visualize the decision-making process of your NPC as it interacts within the game world.

Conclusion

This new Behavior package in Unity 6 streamlines the process of incorporating AI into your games, allowing you to create complex behaviors with ease. I encourage you to refer to the documentation linked for a deeper understanding of all features and capabilities.

Thank you for your support, and be sure to check out more tutorials for advanced AI techniques!

Keywords

  • Unity 6
  • Behavior package
  • AI
  • NPC
  • Finite State Machine
  • Behavior Graph
  • Patrol Points
  • Detection
  • Animator

FAQ

Q1: What is the Behavior package in Unity 6?
A: The Behavior package is a new, officially supported, and free addition to Unity 6 that simplifies adding AI behaviors to your games.

Q2: How do I create an NPC with AI using the Behavior package?
A: You can create an NPC by adding a Behavior Agent component, creating a Behavior Graph, and defining behaviors within the graph using nodes.

Q3: What is the difference between a Behavior Tree and a Finite State Machine?
A: A Behavior Tree uses a graph-like structure to manage actions and decisions, while a Finite State Machine defines clear, discrete states such as Patrol, Chase, and Attack.

Q4: Can I debug the AI behaviors I create?
A: Yes, the Behavior Graph includes debug features that allow you to visualize how your AI is operating in the game.

Q5: Where can I find more information about the Behavior package?
A: You can access the official Unity documentation for detailed insights and tutorials on using the Behavior package effectively.