Building an Intelligent AI System in Unity

Table of Contents

1. Introduction
2. Building the System
3. Creating Actions
4. The State Class
5. Updating the Current State
6. Visualization Tools with Gizmos
7. Drawing the State Gizmos
8. Adding Meshes for Visuals
9. Integrating AI State in Gameplay
10. Conclusion

Introduction

In this article, we will dive into the process of building an AI system in Unity. We will start by creating the system's smallest and simplest parts, known as actions. These actions will be the building blocks for our AI behavior. Next, we will create the state class, which will handle the logic and decision-making for our AI. We will also explore the concept of passing scene references using the delegate pattern to ensure discrete interactions. Additionally, we will utilize gizmos to Visualize the state of our AI agents in the scene view. By the end of this article, you will have a solid understanding of how to implement an AI system in Unity and enhance the visual feedback for better gameplay experience. Let's get started!

Building the System

To begin building our AI system, we need to create the actions that will define the behavior of our AI agents. Actions are subclasses of an abstract class called "Action". We will create a new C# script called "Action" in the scripts folder of our project. This script will contain a single public function called "act", which will be overridden by inheriting classes. Each action will take a "state controller" variable as a parameter.

Pros:

• Actions allow for modular and reusable code.
• Inheritance allows for customization and specialization of behaviors.

Cons:

• Actions may have dependencies on the state controller, which can lead to tight coupling.

Creating Actions

Actions are the core components of our AI system, defining the behavior of our AI agents. These actions will be called from the states in our system, such as "chase" or "attack". We will create a state class next, so right-click on the scripts folder in Unity and create a new C# script called "State". This script will be a scriptable object, allowing us to create state assets in our project. The state controller will update the current state every frame, calling the "updateState" function and evaluating the actions.

The State Class

The state class is responsible for managing the behavior and decision-making of our AI agents. It is a scriptable object that can be assigned as the current state in our state controller. In the state script, we will add a function called "updateState" that takes a state controller as a parameter. We will also add a public array of actions called "actions" to hold the actions associated with this state.

Pros:

• Scriptable objects allow for easy asset creation and management.
• The state class provides a central location for organizing and controlling AI behavior.

Cons:

• State assets can become bloated if not properly organized and managed.

Updating the Current State

Now that we have our actions and state class in place, we need to update the current state of our AI agents. In the state controller script, we will add a public state variable called "currentState" and an update function. The update function will first check if the AI is active. If not, it will return. If the AI is active, it will call the "updateState" function of the current state and pass the state controller as a parameter.

Pros:

• The state controller acts as the central hub for updating and managing the AI behavior.
• Separating the state logic from the actions allows for better organization and ease of maintenance.

Cons:

• The state controller can become complex if there are many states and actions to manage.

Visualization Tools with Gizmos

To provide visual feedback for our AI agents, we will be using Unity's gizmos. These gizmos will help us visualize the state of our AI agents in the scene view. We will draw wire spheres and lines to represent the current state and behavior of our AI agents.

Drawing the State Gizmos

To draw the state gizmos, we will add an "OnDrawGizmos" function in the state controller script. This function will check if the current state and AI's transform are not null. Then, it will set the color of the gizmos based on the current state. We will draw wire spheres at the eye position of the AI agent to represent the field of view. This will help us visualize the AI agent's Perception and behavior.

Adding Meshes for Visuals

To enhance the visual representation of our AI agents, we can add meshes to their Game objects. These meshes can be customized based on the current state or behavior of the AI agents. For example, we can change the color or texture of the mesh to indicate different states, such as idle, alert, or attacking.

Integrating AI State in Gameplay

To fully integrate the AI state into our gameplay, we need to consider how the AI agents interact with other game objects and systems. This can include detecting collisions, triggering animations, or interacting with other AI agents. By utilizing the state controller and actions, we can create complex and intelligent AI behavior that enhances the player's experience.

Conclusion

Building an AI system in Unity involves creating actions, managing states, and visualizing AI behavior using gizmos. By breaking down the system into smaller components and utilizing scriptable objects, we can create modular and reusable AI code. Visual feedback through gizmos and meshes enhances the player's understanding of AI behavior. By following the steps outlined in this article, you can create dynamic and intelligent AI systems for your Unity projects.

Highlights

• Actions are the building blocks of an AI system in Unity, defining the behavior of AI agents.
• The state class manages the decision-making and logic for the AI, while the state controller updates the current state.
• Visual feedback using gizmos and meshes enhances the understanding of AI behavior in the scene view.
• Integrating AI state into gameplay involves considering interactions with other game objects and systems.

FAQ: Q: Can gizmos be visible in the game view for players to see? A: No, gizmos are only visible in the scene view for developers during the Unity editor. They are not visible in the game view for players. However, you can use other visual cues, such as changing the color or texture of AI agents, to indicate their current state.

Resources:

• Unity Documentation: ScriptableObject
• Unity Answers: How to Use Gizmos to Draw Debug Information