Book Image

Unity Artificial Intelligence Programming - Fifth Edition

By : Dr. Davide Aversa
Book Image

Unity Artificial Intelligence Programming - Fifth Edition

By: Dr. Davide Aversa

Overview of this book

Developing artificial intelligence (AI) for game characters in Unity has never been easier. Unity provides game and app developers with a variety of tools to implement AI, from basic techniques to cutting-edge machine learning-powered agents. Leveraging these tools via Unity's API or built-in features allows limitless possibilities when it comes to creating game worlds and characters. The updated fifth edition of Unity Artificial Intelligence Programming starts by breaking down AI into simple concepts. Using a variety of examples, the book then takes those concepts and walks you through actual implementations designed to highlight key concepts and features related to game AI in Unity. As you progress, you’ll learn how to implement a finite state machine (FSM) to determine how your AI behaves, apply probability and randomness to make games less predictable, and implement a basic sensory system. Later, you’ll understand how to set up a game map with a navigation mesh, incorporate movement through techniques such as A* pathfinding, and provide characters with decision-making abilities using behavior trees. By the end of this Unity book, you’ll have the skills you need to bring together all the concepts and practical lessons you’ve learned to build an impressive vehicle battle game.
Table of Contents (17 chapters)
1
Part 1:Basic AI
6
Part 2:Movement and Navigation
11
Part 3:Advanced AI

Chapter 9: Behavior Trees

In a preceding chapter, we saw a basic but effective way to implement and manage character states and behaviors: finite state machines (FSMs). FSMs are simple to implement and intuitive, but they have a fatal flaw: it is tough to make them scale once there are many states and transitions. For example, imagine a character that behaves differently depending on its health and mana (high, medium, or low). We have a state in which both health and mana are high, one in which health is medium and mana is high, one in which they are both medium, and so on. In total, we have nine states just for those. If we add other conditions (such as player proximity, time of day, equipment, player's score, or whatever you may imagine), the number of states grows exponentially.

Luckily, we have a solution: behavior trees (BTs). In essence, BTs are just another way to visualize complex FSMs, but they are fast, provide reusability, and are easy to maintain. After their introduction...