AI Toolkit — Give a brain to your NPCs, a header-only C++ library

Second edition of me battling my procrastination. This time, it is a project I made 1 or 2 years ago that I decided to publish. I was planning the AI for my 4X strategy game Warmonger Dynasty in C++, and I wanted a set of tools to help me implement it.

This is how AI Toolkit was born:

GitHub - linkdd/aitoolkit: Give a brain to your game's NPCs

It provides 4 modules:

• Finite State Machines: a nice abstraction of state management, useful for animations, or scripted actions
• Behavior Trees: an extension of state machines which allows you to compose a decision tree where each node implement part of the desired complex behavior
• Utility AI: to determine the best action to perform in a specific situation
• Goal Oriented Action Planning: to find a sequence of actions capable of achieving a specific goal from a given situation

The combination of those tools enables the implementation of complex AIs without necessarily needing machine learning.

I generally use FSMs to handle global state management and the UI, to control which menu to display when, and when to pause the game or resume it.

Behavior Trees are great to implement scripted behaviors, like an NPC patrolling the area, and attacking any enemy it sees.

Utility AI can be used to determine which goal is best to pursue. Then, combined with Goal Oriented Action Planning (GOAP from now on), we can determine the sequence of actions to take to achieve that goal. For strategy games, it gives a great flexibility to the AI.

Nothing prevents you from sprinkling some Q-Learning on top of it to make your AI learn, but this is not yet provided by this library.

Ok let’s dive in now 🙂

📦 Installation

Since it is a header-only library, all you need is to add the include folder to your include paths, and a compiler supporting at least C++20…