Strategy

Strategy

One-line pattern summary

A pattern that encapsulates algorithms with the same goal behind an interface so they can be swapped at runtime.

Typical Unity use cases

• When AI attack behavior should change by situation.
• When aiming or movement policies differ by character.

Parts (roles)

• Strategy Interface
• Concrete Strategy
• Context

Unity example (C#)

The code below is a simplified Unity example based on the scenario described above.

using UnityEngine;

public interface IAimStrategy
{
    Vector3 GetAimPosition(Transform shooterTransform, Transform targetTransform);
}

public sealed class DirectAimStrategy : IAimStrategy
{
    public Vector3 GetAimPosition(Transform shooterTransform, Transform targetTransform)
    {
        return targetTransform.position;
    }
}

public sealed class LeadAimStrategy : IAimStrategy
{
    public Vector3 GetAimPosition(Transform shooterTransform, Transform targetTransform)
    {
        return targetTransform.position + targetTransform.forward * 0.5f;
    }
}

Advantages

• Behavior is separated into smaller units, which reduces the impact of changes.
• Adding or swapping rules is relatively safe.

Things to watch out for

• As the number of objects and indirect calls increases, the flow can become harder to follow.
• Ordering bugs should be pinned down with tests.

Interaction diagram

This shows the flow where a context swaps algorithms through a strategy interface.