What it takes to get an NPC running around in game. Part 1: Rigging & Animating. (Patreon)

Alright, fellas, Rigman here; it's time to dive into the more technical and animated side of things in Shot One. In this post, I'll be showing off what we're internally calling the "vaultbot" this is an NPC you'll run into in one of our exploration 'dungeons'. They're not very friendly and have a few forms with unique abilities you'll have to contend with. They're basically our 'koopa troopas'.

So let's jump into it; as a general overview, once the asset has been created, it goes through a series of steps before it's game ready. I'll take you through today's first step, "Assessment and Organization".

When a new asset comes in, certain things might need to be more organized. Things like making sure the correct material IDs are set, cleaning up how the model is consolidated, and just making sure naming conventions are organized. These seem like small things to worry about, but taking care of them now just makes your life significantly easier down the line when eventual problems creep up. For our 'vaultbot' here, it will have four variants, and to make our lives easy, we want them to share a singular rig. Below is an exploded view (b.) of the model so you can see each variant. They all share the same base model, and we can enable which one we need at any given time.

It's time to move to my favorite part, "Rigging." This process involves putting virtual bones inside the model and hooking them up with controllers. Below is a gif showing an early form of the lower half of the rig in action. I'd likely dedicate an entire post to the process and techniques I use, but we'll leave it here for now.

The vaultbot is on the simpler side of characters when it comes to rigging, so for this character, I just built the entire rig before I moved on to the next step. I likely wouldn't take this more relaxed approach for more advanced characters. But you can see the completed rig, the bones, and its controls below.

Now we move on to the second part of rigging, "Skinning." Skinning is a process where you paint the model with specific colors to dictate how much influence a given bone has on a given vertice. Because I'm not a masochist, I use a color ramp instead of grayscale. This allows me to see more easily how much influence a bone has. White means 100% influence, yellow is 50%, and black represents 0% or no influence. The vaultbot being more mechanical means most parts will have 100% influence on a given bone. Still, in the image below, there are areas where I want the geometry to deform, and you can see the color ramp in that image very clearly. This approach will allow me to get a bouncy butt for the “goop” variety. I want to lean into the baneling fantasy.

With skinning done, we're almost complete with the entire rig. I even put a little control that allows me to swap variants on the fly, which will streamline the animation process later. But even with that, we're only about 90% there; the final step of the rigging process is clean-up!

I don't want to animate some disgusting-looking rig; I want something easy to use, functional, and pleasant to look at.

And just like that, we have a completed rig with a bit of test animation to boot. From here we can now enter the next phase. Animating.

We need a whole set of animations to get the character working in the engine. This usually involves various directional movements, attacks, spawn and destroy animations, and any other actions you might want the NPC to perform. I typically have one primary scene file for each set where I build every animation in sequence; you can see an example of a few of them below or the entire animation set (animset) above in the video accompanying this post. We take this approach to minimize the amount of data that you need to import. 

You might notice some animations where only some parts were animated or how we had held poses or frozen elements. Much of that is due to some animations being built to be layered or have simulated physics applied to certain bones. This is something that I'll go more in-depth on in part two.

Once I have a solid enough set to work with, I begin importing these into the engine. I then clip the animations and build the logic that drives the animations in the game. Although, we're going to cut it here though and save that for part two.

-Rigman