Add a new stat to EntityLiving using ASM

[Mithion]

Hi all,

 

In the mod I'm working on, I currently modify a base class (I know, I know) with a variable for all my custom data on EntityLiving.  It's a public final instance of a class that contains all the new data.

However, realizing that's bad, I'm trying to make my mod base-clean.  I have managed to get everything else out of base classes and working save for this.

 

I'm thinking of using ASM to inject the field and the changes to a few functions, but I can't seem to find an entry point to get this to happen.  According to the ASM documentation, the byte array generated by my ClassWriter needs to go into a ClassFileTransformer in order to affect everything, but I can't seem to find this anywhere.  I see that IClassTransformer seems to do this, but I don't see a way to register in to take advantage of that functionality.

 

Either way, I'd really appreciate if someone could point me in the right direction.

 

Cheers!

 

EDIT:  I have the class loading and field/method manipulation working (testing by outputting the class to a file, reading it back in, then iterating over fields/methods) - but now I need to know how to overwrite the existing class in the game with the modified bytecode.  It seems to me that the RelaunchClassLoader is what does this for forge.  Is there any way to register an additional transformer with the static instance of this class?  It seems like that would solve my problem.

 

EDIT 2:  Okay, so I'm apparently talking about a CoreMod.  I'll poke around other projects to see what I can find, but if anyone has a good resource to share with me, you would rock!  When I get it working (and I will), if nobody's given me an existing one, I'll see about making a tutorial for it. 

[OvermindDL1]

You can attach arbitrary NBT data to any entity, why would that not work for you?

[Mithion]

That would work perfectly, if I can store and retrieve an instance of the ExtendedProperties class for each individual entity.

 

Is there an example of this anywhere that you are aware of?  I haven't really seen this done before when I searched.

[OvermindDL1]

Near the end of the variable declarations on Entity or EntityLiving or whatever it was there is a commented variable saying that it was added by Forge for just those purposes.  You can read from and write to it just like an normal NBT data. 

[Mithion]

So there is.  I thought that was just for saving to file, on close for example.

 

But I suppose if I catch the spawn event for an  EntityLiving (provided it exists, I haven't looked yet), I can inject it right away and access it without needing CoreMod functionality.

 

Though it is accessed several times per tick through various means, I wonder if there would be performance impacts on using it that frequently?

 

Either way, that's for a different topic.  Thanks very much for your help!