How to use the Rigify building blocks for non-human rigs?

Question

The Rigify documentation says that

It is based around a building-blocks approach, where you build complete rigs out of smaller rig parts (e.g. arms, legs, spines, fingers...). The rig parts are currently few in number, but as more rig parts are added to Rigify it should become more and more capable of rigging a large variety of characters and creatures.

Based on this description I assume that it should be possible to create arbitrary (non-human) rigs with Rigify. However, all the Rigify tutorials I found start with the creation of the human meta-rig from the add menu, and no additional bone is added to it. I see that in Edit mode I can "add a sample" from a list of items, but I don't understand how to use it. For example how could I rig a spider with Rigify?

EDIT I found a BlenRig vs Rigify thread on blenderartists.org where everybody agreed that Rigify (as opposed to BlenRig) should be able to handle non-human characters. (But they didn't say how exactly...)

"Rigify is a general purpose template based system and it will let you create custom rigs for any character without really needing to know the mechanisms behind the rig. (...) On the other hand, BlenRig has a more limited use, cause it is (for now) intended for humanoid characters. So, any other rigging procedure would have to be made manually. In other words, if your character has 4 arms, you will have to duplicate BlenRig's arms in Edit mode manually, there is no "add arm" button."

"Rigify is intended to be/become a very general solution for creating the armature and controls of any character via a building-block/template paradigm."

EDIT 2 To clarify, my basic question is: how should I use the "Add sample" button (which appears in Edit Mode in the "Rigify Buttons" panel, see the screenshot bellow) that adds a rig building block? Am I not supposed to use it? (that would be weird). If I am supposed to use it, what are the rules for building a meta-rig? Can I build a meta-rig from scratch or should I always start with one of the two meta-rigs (Human and Pitchipoy Human)? Can I combine Human and Pitchipoy Human building blocks in one meta-rig or are these incompatible?

Answer 1

Create an armature and enter its edit mode. Delete the bone to start fresh.

You can build a custom metarig from "samples" that you can add in. Later this metarig is used to generate the rigify rig.

To know what samples to use for your use case try them out and see what they do.

Each sample will be added in the scene origin. Position the samples like you want, align them to your character. Parent them to form the metarig. You can create the human metarig that you can add as a whole from samples or you can create your own metarig (one with 4 arms for example). There are also animal parts available.

You can mix them how ever you like.

You can also add your own bones and make them 'Rigify-able'. In Pose mode select a bone and inside Rigify Type tab in bone properties you can change the parameters:

You can change on which armature layers will Rigify generate bones and customize other settings. This can be changed on the sample metarigs and on the individual samples as well.

You can see what the options do in the addon documentation (Advanced usage section).

Then generate the Rigify rig from your metarig.

Answer 2

About having to use existent blocks: your mistaken. See, while rigify only hands you types specic for human rigs, these types are fairly small and universal. Also the 'hidden' property is actually to be found in posemode, in the property-panel under the tab 'bone' in the panel on the very bottom.

You can use any bone structure you like and add select the type for the rootmost bone, as long as you fullfill at least the requirements for the rigify-type. after creating your meta-rig you can save it to a textblock by pressing the button 'Encode Metarig to Python' in the toolshelve, under tools at the very bottom (in the panel 'Rigify Dev Tools'). The produced textblock you then would save as .py in the folder 'metarigs' in the folder 'rigify' in your addons. Close blender, open blender, disable and re-enable rigify and your custom metarig is on.

Now about your spider: Sadly adding a new rigify-type is only possible with python. While im developing a sub-addon, that gives rigify the ability to encode your rig to a rigify-type, here is a simple workaround:

The leg of a spider mainly consists of 3 Bones and a small appendix. You could use a biped arm as base, and ignore the appendix or create it manually after generating the mesh. OR you could use a spine, add a bone and define its controlles. (there is a panel in the bones-tap wich lets you enter integers, seperated by comma+space. Only those bones will get a controll-handle.)

I'm currently developing a sub-addon, that shall later give the ability to auto-encode existent rigs to rigify-types (and a s-load of other stuff). I'll try to inform you once that feature is stable.

Answer 3

I could be wrong, but as I understand it, the Rigify addon is made specifically for rigging humanoid characters. To rig a spider you'd be better off building the rig from scratch. The idea i guess would be that you could copy eight arms and delete the spinal column and get something that works, but I think that the rigify documentation is talking about say, a humanoid creature with four arms. The benefits of Rigify are that you get a bunch of complex controllers to more easily control your mesh, and i think that the controllers might be more of a hinderance than a help if you managed to properly edit the human meta-rig. I hope this helps, if you need help building a rig from scratch, I recommend using methods shown in David Ward's tutorials on youtube.

Answer 4

As mentioned on the addons page rigify is built using a building blocks approach, allowing different rigs and rig components to be added to the system.

So far only two biped rigs have been added to this system.

If you look through the files for the rigify addon you will find some fairly detailed information in the README and looking through the scripts used to create the existing rigs you should find more info on how the rigs are built. You may also notice that the pitchipoy rig includes support for a tenticle and paw.

Note that the rigs are completely generated using python scripts, they are not pre-generated armatures saved in a blend file.

You may also want to experiment with the existing rigs, they might be more flexible than you may think. While removing bones currently breaks the generate step, you can duplicate existing bones and get multiple parts in the final rig (and delete extra bones from the final generated rig).