Rigging is (almost) done!

So the vast majority of figuring out how to do a proper rig in Blender is done! In case you're wondering why it took so long (2 months of every day dedicated work, in fact), well, there are no learning materials available for such advanced level rigs out there in the internet, simply nothing of use. 

To develop such high-level production-ready rig in Blender I spent lots of time on something that is called R&D (Research and Development), solving problems, engineering, and even programming custom scripts to make a proper and comfortable toolset for animations. There is still a bit more left to write, but thankfully I already got decent grasp of Blender's Pyhon API (or so I think).

I feel like what I did is really important not just for this project, not just for you and all the future modders, but for Blender community as a whole. I could, of course, do it in Maya and it would take much less time, but then people wouldn't be able to use the rig without spending thousands of dollars to get the software required! Not even if all they want is to just play around and make lewd poses, or export the model into other games (like how someone already did it for VRchat).

The rig is not yet production-ready, some things need to be refined first, but the overall functionality is there, I'm posting a lot of GIFs (I hope you're not on a limited mobile plan, cause that stuff is heavy) and explaining some of the things it can do:

At first glance it's just an Inverse-Kinematics leg, one that you might have seen in many rigs already. But look closer, it is digitgrade. While this is what all sexy creatures should have in my opinion, most rigging techniques are only designed for human legs (plantigrade), thus it was a challenge to find the proper and most comfortable way to control them. 

The leg IK system also done in a technique called "no-flip knee" which, in a nutshell, automatically determines where the knee should be located at, without the need of manually adjusting it to avoid it "breaking" the leg or "flipping".

The rig is also 100% stretchy, meaning it can provide functionality for those classical cartoon animation techniques. Even when making realistic animations, it never hurts to have just a little bit of stretch and squash, which is one of fundamental animation principles.

The foot itself can be rolled back and forth, banked from side to side, and toes can be curled - all this working in tandem creates that range of motion that is invaluable when creating walk animations. After all, walking is 90% of all animations that characters do in any game.

Also the rig is built to support a big variety of feet, since every race has pretty much unique anatomy: 3-toes one of which is a "raptor claw" for Hizathri, or 4 toed Sergal paws, or even bird feet with a back-facing toe! People who like feet will not be disappointed :}

In this example I'm showing the separate adjustment controls for knees and heels and ability to lock any control in place: chest is locked, but pelvis moves, tail and legs are following it.  The goal was to give a lot of freedom over the pose with as little animator effort as possible, and even a bit extra. 

Like here, I locked everything to the place, the character is now standing on his knees, which is a very useful feature when making animations for climbing, knocked-down/low-health crawling and mating. 

Speaking of the tail, it utilizes splines and provides hybrid IK and FK controls. Splines are mathematical curves that you were probably really bored of in school, but they provide very nice smooth paths in 3d space.  

If you use Blender: splines they are very finicky to setup in Blender in a way that they don't lag behind 1 frame. I hope that one day I'll make a bunch of tutorials how it is done, but for now you can just ask me directly for technical details. 

Animator can decide where they want the tail to be rotated manually or automatically, meaning that instead of animating all 14 bones within the tail  individually, one can achieve the same result by animating only, say 3 of the bones. But if they really need full control, they can switch it on and do whatever they please! I can't wait to make some booty swings with this rig ^^

Exact tail pose can be adjusted with special tweak controls, animator can really give it any shape that might be needed. 

Also notice the tail sliding in-and out like it's on a track - its all intentional and will have its invaluable use for some specific cases, especially since the same system is used for the tongue and, well... another grabby prehensile tentacle-like things you find creatures have, if you know what I mean :}

The spine rig.. ooh how much trouble it gave me! I went through 5 different prototypes in order to find "de wey" of making it properly. 

To come up with this solution, I've spent days experimenting and writing down my successes and failures, like a true scientist. During this I even wrote a few-pages length guide on how exactly the thing was setup for myself to not forget in the future:

Don't bother, however, reading all that in the gif above, in the end I've developed a much simpler and better solution to this problem, which I'll share later (or if you really need it now you can ask me directly, I'll help ya)

If you're a rigger you might think "Why?! It's easy, just use splines like you did for the tail!", but nope, I'm using b-bones, Blender's unique (sort of) feature of making, well, bendy bones. And I'm using it for a special reason that splines just don't provide.

Problem though, those b-bones can never be exported into Unreal Engine (or anything really), "so what's the point of making them?" you might ask... Trick is that they are used to drive another set of bones that can be exported! 

Another problem is that neither splines, nor B-Bones (when used as drivers) support twisting around. They just don't hold any rotational information in them, nor you can really access it externally. 

This is the area which I struggled with the most: Blender's rotational math is... well, let's put it that way, "it's rather limiting", without swearing and delving into technical details.

But in the end, as you see, both neck and spine are very flexible and can twist in a very organic way. 

I was trying to achieve this effect mathematically, but, again, turns out blender is not doing good on that front when it involves rotations... 

The final solution to that riddle was proposed by Hopfel: it was for a completely different part of the body and was done in a very mechanical way (which made us feel like engineers), but then I realized that I could apply it to the spine, and it truly saved the day!

Going further up, here is a little demonstration of mouth and tongue, nothing fancy to say here, other than the tongue behaves just like the tail, as I already mentioned.

Now let's look at arms. Standard IK-chains usually involve only 2 bones as it moves lower and upper arm bones to reach the desired end-goal position. 

Think about it if you hold onto something and try to swing your chest around - your hand stays in place but arm takes appropriate pose in-between your shoulder and the hand. GIF below should illustrate that:

Blender is a great collection of very good and unique features, but first, they are very well hidden, second, there is no documentation about them, third, they are built on age-old legacy foundation which doesn't get updated. This is one of such hidden techniques, rotational IK solver.

What is unusual about this arm IK rig (at least for people with a more traditional rigging background, like me) is that it involves everything, the arm, the hand and even the clavicle. The bones themselves take optimal pose based on how "stiff" some bones are, for example, clavicle moves only after the arm has reached its full length. There are also limits in how much a certain bone can rotate, for example, forearm can only be rotated one axis, bent towards and away from the bicep. 

I didn't know blender could do that, but thankfully this technique was shown to me by a fellow scalie blender animator, Doublescale (aka  scale2x ) Even though its not the as advanced as the rest of the rig, it saved me so much time. ^^

Just how we already established, solving twisting with constraints and math is not an option: it will eventually break and flip all the rotations, leaving you with a totally distorted, unusable bodypart (sounds as nasty as it feels, ugh).  

Wrist uses the solution that Hopfel figured out, the one I later ended up using for the spine and neck. The arm can be freely rotated, and the lower arm, or anatomically speaking, Ulna and Radius bones are properly rotated.

Of course, just having IK is not enough, the rig is capable of switching to the regular good-old FK mode when needed, both arms and legs have IK-FK switches.

For reference: like how said before IK is useful when character holds onto something or steps onto the ground, FK is when the motion originates from the beginning of the chain (shoulder or hip), for example swinging arms in the air is much easier to do with FK, while holding a handle of a door is easier with IK.

And last but not least, I here are the belly controls. 

I recently expanded their functionality greatly, I was inspired by Monster Hunter World footage where creatures just can swallow eachother, getting their belly huge!

I added such controls all the way starting at the throat, ending at the butt, all character functional length can have something wiggling inside animated, or just inflating the innards for whatever reason might be needed. 

General fatness, vore, food fullness, and pregnancy - a lot of possibilities open up in the future; so maybe there will be indeed some content for the belly and maw lovers, we can explain anything with SCIENCE, for example having the belly "bigger on the inside" or having a "very stretchy throat" and things of that nature. 

Is it realistic/organic/natural to have in our game? Well, what if the creature uses some space-time warping abilities inside their belly indeed?

The game isn't about making 1 to 1 nature simulator, it's about building laws of physics that stay constant throughout the game, and giving creatures natural necessities, such as full food digestion, reproduction, response to environment around (wet/dirt/heat/cold), health and diseases... things of that nature.

I think I'm getting derailed from the topic of the rigging, so I'm going finish writing for now, but stay tuned for the part two follow up on this - I haven't covered everything the rig can do, plus there is a few more extra things that still need to be done yet.

Hope you too had a productive January :}
See you soon!
Salireths.

PS: This post is over 1700 words, thank you for reading ^^ I really appreciate you following the updates, I'd gladly have them turned into a video format like I used to, but currently I just can't afford spending time on video production, it would take around a week to fully prepare something like that, I think I better focus on having the next playable game version released sooner.