A Spell System

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I created this spell system for my game a little while ago. Basically, my goal was to create something like the item system, whereby you create a new item by filling out details in the datablock and writing a few scripts. The rest should be handled for you behind the scenes (in code).

So here is is. Basically I have created a Spell object in source code. All you do to create a new spell type is fill in a few of the "stub" scripts, such as onBeginCasting and onTick. The spells can do anything you could do with a script, hurl projectiles, heal, teleport, whatever. As long as you have the scripting ability.

To use the spells, add the .cc and .h to your source code and recompile. Then add the spells.cs to your server directory. Make sure you remember to exec it in game.cs. Just after you exec it, put this line :

InitSpells();

Add the Spells folder from the zip into the server directory as well. If you write new spells, put them in there. The InitSpells() call will ensure they are loaded up.

Now, to cast a spell, you simply create a new Spell object, just like you would create a projectile. You create it on the server. Note, the spell itself does not get ghosted across to the client. But any effects you create might be. So for example in the fireball spell, I just create a projectile. It handles ghosting itself across. Likewise, the heal spell restores players health. The player object handles transmitting that data across, there is no need to send the spell object itself.

Here is code that creates a spell object, just add it at the end of player.cs :

function Armor::castSpell(%this, %obj, %spelldata)
{
   %energy = %obj.getEnergyLevel();

   if(%energy > %spelldata.manaCost)
   {
      %obj.setEnergyLevel(%energy - %spelldata.manaCost); 
      
      %spell = new Spell()
      {
         datablock = %spelldata;
         caster = %obj; 
         casterLevel = 10;     
      };

      MissionCleanup.add(%spell);
   }
}

How you call that function is up to you, you could use a Server Command, personally my player stores a "current spell", and clicking the right mouse button calls this function. Note also the hard coded caster level. The Invisibility spell is an example of how to use caster level as a multiplier of the spells effect, in this case duration.

Spells have a casting time, after that time has finished the spell begins "ticking". It ticks for the duration, then ends. If you want effects (eg. particles) to occur while the player is casting, create them in onBeginCasting and clean them up in onEndCasting. Put the actual spell effects in onEndCasting and onTick. If the spell is instantaneous, like Fireball, just put the code in onEndCasting. onDurationEnd is called when the spell ends.

Note, the duration might not be exactly what you set it to be, as the processing occurs once every 32 ms. If the spell is not a multiple of that, it might get an extra "tick".

I have included some example spells in the .rar, Fireball, Heal and Invisibility. Take a look at those to see how its done.

Have fun!