Expanding NPC Sprite sheets

This is a tutorial for expanding the NPC sprite sheets to include all of the actions of a PC sprite sheet. This will enable you to make much more interesting and natural custom events.




***Sorry about the video quality. Youtube apparently does not maintain the quality of the video uploaded. I'm new to uploading vids so if anyone knows a fix let me know so I can make this a little more clear.


It's a pretty straightforward process:

First you need to get yourself a sprite sheet and get it imported into a dummy ROM (alternatively you could import it into your working ROM, but you will have to reimport whatever sprite you replace later). Once you get it fully working with your hacks palettes you need to copy the data to a new location. Using FF3info.txt you can see where the sprite you replaced should start and end, which will give you the bounds for the sprite sheet you imported. I always import over Terra since she is pretty easy to find and I have her offsets memorized. D5/0000 to D5/169F. So grab all that data and paste it somewhere you have $16A0 empty bytes (I copy it to F5/0000). You now have a whole extra sprite sheet in your ROM... but now your game needs to know what it is and when to use it...

The next step is to fix your Overworld and NPC sprite pointers which are in two different tables:

C0/D23C - C0/D385 (Bank pointers)
C0/D0F2 - C0/D23A (Location pointers)

For both tables each entry is two bytes long, so in order to find your offset, find the NPC you want to replace (make sure the spriteID is converted to Hex), double it, and add it to the start of each table. So for Arvis (sprite ID 29, or $1D) you need to change the values at D276 (1Dx2 + D23C) and D12C (1Dx2 + D12C)... Alternatively, you could just count it out two bytes at a time the way I do in the video.

Then you are done! You should now have your expanded sprite sheet called by the game when it loads the NPC. However, there are a few notable differences between NPC sprite sheets and PC sprite sheets when it comes to events. Many NPCs (including Arvis) only have one additional sprite, the event queue command to call the NPC additional sprite is 2D, you will need to replace every instance of this call for your NPC to whatever action that NPC is supposed to be doing there. That being said, you are opening up a world of possibilities for your NPCs.

If I am lucky, I will be posting 2 more videos in the next couple months that build on this one. The first will enable our imported sprites to be able to called in battle and will likely cover expanding portrait data for your new sprite. And the final video (if I am able to get everything worked out) will be a tutorial on enabling your new sprite to be called in shop, save, and party menus, effectively making your sprite 100% playable as a PC.

I hope this helps with those of you who are doing a lot of custom events and makes you excited for the things that are possible when you hack FF6.

Happy Hacking!