Book Image

Unity 5.x Game AI Programming Cookbook

By : Jorge Palacios
5 (1)
Book Image

Unity 5.x Game AI Programming Cookbook

5 (1)
By: Jorge Palacios

Overview of this book

Unity 5 comes fully packaged with a toolbox of powerful features to help game and app developers create and implement powerful game AI. Leveraging these tools via Unity’s API or built-in features allows limitless possibilities when it comes to creating your game’s worlds and characters. This practical Cookbook covers both essential and niche techniques to help you be able to do that and more. This Cookbook is engineered as your one-stop reference to take your game AI programming to the next level. Get to grips with the essential building blocks of working with an agent, programming movement and navigation in a game environment, and improving your agent's decision making and coordination mechanisms - all through hands-on examples using easily customizable techniques. Discover how to emulate vision and hearing capabilities for your agent, for natural and humanlike AI behaviour, and improve them with the help of graphs. Empower your AI with decision-making functions through programming simple board games such as Tic-Tac-Toe and Checkers, and orchestrate agent coordination to get your AIs working together as one.
Table of Contents (15 chapters)
Unity 5.x Game AI Programming Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Avoiding walls


This technique aims at imitating our capacity to evade walls by considering a safety margin, and creating repulsion from their surfaces when that gap is broken.

Getting ready

This technique uses the RaycastHit structure and the Raycast function from the physics engine, so it's recommended that you take a refresher on the docs in case you're a little rusty on the subject.

How to do it...

Thanks to our previous hard work, this recipe is a short one:

  1. Create the AvoidWall behavior derived from Seek:

    using UnityEngine;
    using System.Collections;
    
    public class AvoidWall : Seek
    {
        // body
    }
  2. Include the member variables for defining the safety margin, and the length of the ray to cast:

    public float avoidDistance;
    public float lookAhead;
  3. Define the Awake function to set up the target:

    public override void Awake()
    {
        base.Awake();
        target = new GameObject();
    }
  4. Define the GetSteering function for the following steps:

    public override Steering GetSteering()
    {
        // body
    }
  5. Declare and set the variable needed for ray casting:

    Steering steering = new Steering();
    Vector3 position = transform.position;
    Vector3 rayVector = agent.velocity.normalized * lookAhead;
    Vector3 direction = rayVector;
    RaycastHit hit;
  6. Cast the ray and make the proper calculations if a wall is hit:

    if (Physics.Raycast(position, direction, out hit, lookAhead))
    {
        position = hit.point + hit.normal * avoidDistance;
        target.transform.position = position;
        steering = base.GetSteering();
    }
    return steering;

How it works...

We cast a ray in front of the agent; when the ray collides with a wall, the target object is placed in a new position taking into consideration its distance from the wall and the safety distance declared and delegating the steering calculations to the Seek behavior; this creates the illusion of the agent avoiding the wall.

There's more...

We could extend this behavior by adding more rays, like whiskers, in order to get better accuracy. Also, it is usually paired with other movement behaviors, such as Pursue, using blending.

The original ray cast and possible extensions for more precise wall avoidance

See also

For further information on the RaycastHit structure and the Raycast function, please refer to the official documentation available online at: