How to design the attack class in an RPG game?

Question

I am in the planning phase of a small RPG style game.

The character will have have a set of attributes, like strength, agility, etc which are represented as integers. The character also will have a set of attacks represented as an attack class.

On each attack I want it to do damage based on the characters attributes, eg: the attack "sword slash" will do 10 dmg + the value of the characters strength.

The way I was thinking to do this is to have an abstract attack class, which has an abstract Attack method, and for each attack I create one class that implements the Attack method.

public class SwordSlash:Attack
{
    public void Attack(Character attacker, Character defender)
    {
        defender.DoDamage(10 + attacker.Strength);
    }
}

I see that this will make it a nightmare to maintain.

Does anyone have an idea of how I can accomplish this in a nicer way?

What I think is the main problem is how to input the correct attribute, based on the attack.

Answer 1

You should probably go for a data-driven design here.

Make a generic Attack class which contains the parameters you want to work with - base damage, which stats affects the damage, a set of potential status effects... stuff like that:

public enum AttackStat
{
  Strength,
  Agility,
  Intellect
  // etc.
}

public class Attack
{    
  private int baseDamage;
  private AttackStat stat;
  private double damageMultiplier;
  // ...and so on

  public void Attack(Character attacker, Character defender)
  {
    defender.DoDamage(baseDamage + attacker.GetStatValue(stat) * damageMultiplier);
  }    
}

// Put a method on Character to fetch the appropriate value given an AttackStat:
public int GetStatValue(AttackStat s)
{
  switch(s)
  {
    case AttackStat.Strength:
      return strength;
    case AttackStat.Agility:
      return agility;
    // etc.
  }
}

Then, place your attacks in a file, e.g. an XML file, and load the data from there:

<Attacks>
  <Attack name="Sword Slash" damage="10" stat="Strength" multiplier="1" />
  <!-- More attacks here -->
</Attacks>

You could even extend this to draw values from multiple stats, say, a Fireball where the damage is calculated from both an Intellect and a Fire stat:

<Attack name="Fireball" damage="20">
  <StatModifier stat="Intellect" multiplier="0.4" />
  <StatModifier stat="Fire" multiplier="0.8" />
</Attack>

If you don't want to use the same basic damage formula for everything (e.g. calculate magic damage differently from physical damage), create subclasses of Attack for each formula you need and override Attack, and specify which type you want in your XML file.

Answer 2

You want to read Aggregate Objects via Components and Game Object Construction Rabbit Hole, from the Replica Island blog.

Answer 3

I would have a weapon class that has an attack method which you override with the behaviour you want. You can then also handle how the weapon looks in game, in inventory, how much it sells for etc in the same class.

Answer 4

I'm really new to this, but the way I'd do it is to create a generic attack class.

When one character instance wants to attack another character instance it would create an instance of the attack class, filled with the data required, and the ID of the character that created it. Adjustments from gear would then be applied to the attack object, using data that could be entered in an xml document or similar.

This class instance would then be wrapped inside another class, to provide hooks for the environment to determine range or similar. If the attack is valid the attack instance would be passed to the character being attacked, who would apply the effects.

Hope that made sense.