How to Use Interfaces in Game Development C#

What is an Interface

In C#, an interface defines a contract for a class to implement, specifying a set of methods, properties, and events that the class must provide. Interfaces are a good way to implement modular code structure. To implement an interface, a class uses the “interface” keyword, followed by the name of the interface it is implementing. For example:

interface MyInterface {
    void DoSomething();
}

class MyClass : MyInterface {
    public void DoSomething() {
        // implementation
    }
}

In this example, MyClass implements MyInterface by providing an implementation for the DoSomething method.

A class can implement multiple interfaces by listing them after the class name, separated by commas. For example:

class MyOtherClass : MyInterface, AnotherInterface, YetAnotherInterface {
    public void DoSomething() {
        // implementation
    }
    // other interface implementations
}

You can also use interface implementation in a similar way with structs and delegates.

How to Use Interfaces in Game Design?

In game design, interfaces can be used to define common behavior or functionality that different game objects or components can implement. For example, an “IPlayer” interface could define methods such as “Move()” and “Shoot()” that are common to all player characters in the game, regardless of their specific implementation.

Another example could be an “IDamageable” interface, which defines a method such as “TakeDamage(int damage)” that can be implemented by any game object that can take damage, such as enemies, player characters, or destructible objects.

By using interfaces in this way, you can create a more flexible and modular game architecture, where different game objects can easily share functionality and interact with one another.

Here’s a simple example of how interfaces can be used in a game:

interface IDamageable
{
    void TakeDamage(int damage);
}

class Player : IDamageable
{
    public int Health { get; private set; }
    public void TakeDamage(int damage)
    {
        Health -= damage;
    }
}

class Enemy : IDamageable
{
    public int Health { get; private set; }
    public void TakeDamage(int damage)
    {
        Health -= damage;
    }
}

In the above example, the IDamageable interface defines the behavior of how damage can be taken by any object. The Player and Enemy classes both implement this interface to take damage, but have different health values and different ways of handling taking damage.

You can also use interfaces to define common functionality for different types of game objects, such as a “IMovable” interface for objects that can be moved in the game, or an “IAttackable” interface for objects that can attack.

In addition to this, you can use interfaces to define common functionality between different systems like physics, render, AI and so on.

For further understanding on Interfaces in C# here is a video from indie game developer CodeMonkey.

Interface Segregation Principle (SOLID principles)

In object-oriented programming, the interface segregation principle (ISP) states that a class should not be forced to implement interfaces it does not use. In other words, a class should only be required to implement the methods and properties that are relevant to its behavior. This principle is particularly relevant when working with interfaces in C#, as it can help to promote a more modular and maintainable codebase.

For example, consider an interface called “IAnimal” that defines methods for eating, sleeping, and reproducing:

interface IAnimals {
    void Eat();
    void Sleep();
    void Reproduce();
}

If a class called “Fish” only needs to implement the methods for eating and reproducing, it should not be forced to also implement the method for sleeping. Instead, it would be better to create two separate interfaces:

interface IEat{
    void Eat();
}
interface IReproduce{
    void Reproduce();
}

and the Fish class can implement these two interfaces only.

By adhering to the ISP, you can create a more flexible and modular codebase, where classes only implement the methods and properties that are relevant to their behavior. This can make it easier to understand the relationships between different classes and interfaces, and can also make it easier to add new functionality or make changes to existing code.

In practice, you will see ISP is often combined with SOLID principles, which are a set of principles for designing maintainable and scalable software.

For further understanding on SOLID principles in game development please check out the e-book by Thomas Krogh— Jacobsen