Hand IK bones are actually easy
Creating IK bones is something that less experienced users rarely attempt, considering it rather confusing stuff. On the other hand, most new models are created with pre-made base bodies, already with bone structure that includes IK bones, so the need rarely arises. Still, there’s a particular case, one of those that often make video makers scratch their heads, wondering “Why don’t modelers do it by default?” Indeed, having an option to manipulate model’s hands by IK bones can be useful in many cases… fortunately, for this particular demand there’s an easy solution.
The IKMakerX plugin for PMX Editor created by “kaz” of paperguitar.com allows to create hand IK bones practically in two clicks. (There’s also an earlier version of the plugin on the site that supposedly works with .pmd format, but it’s not as easy in use… besides, converting models to .pmx format has lots of other advantages anyway, so there’s just one more reason to do it :D )
The eoscustom3d’s translated version of PMXE (currently recommended by our Downloads page) already has the IKMakerX plugin translated as well, along with several others. If for some reason you can’t or won’t use that one, you can download the original Japanese version of the plugin from its homepage and unpack it into your PMXE’s “_plugin/System” folder. Now load your model (if it’s a .pmd, it will be converted automatically) and launch “Edit->Plug-in->System->IKMakerX”. In the panel that opens hit “Run”… and your model already has IK hand bones! Told you it’ll be two clicks!
All right, if it’s so simple, you think, then why there are all these other options? There are ways to finetune your IK bones a bit.
- First, you can determine whether you want IK bones on both hands, or just one. Why would you want to? Well, who knows, maybe you have a model that is disabled. Anyway, all options are doubled for each IK chain.
- You can change which bones go into an IK chain. By default, all standard bones are already set up there, but you can create a chain of completely different bones. Simply select a bone from the list on the left — controls next to “Original Bone” fields will become hittable buttons — and by hitting these buttons you substitute respective bone names. Thus, you can try to create IK bones for bodyparts *other* than hands (whatever FrankenMiku you will get as a result is not my responsibility, though). Note: if your model *doesn’t* have bones with standard Japanese names for hands, the plugin will not run. Even if you don’t plan to use the plugin on hands, your model must have them.
- This is the parent bone to which your IK bones will be subservient. By default, the Upper Body bone is selected, but you can change it to something else: Center, or Motherbone, for example. (Glass Cage pantomime, anyone?)
- You can change the way your IK bones will be named, if you want to. You can as well rename them later in the Bones tab of the PMXE.
- There are two settings that you *have* to think properly before hitting “Run”, depending on the type of the motion you have in mind for your model. First one determines whether the shoulder bone should be participating in the IK chain. Second one — whether the wrist should be aligned with the forearm during the movement, or keep its own orientation.
- These fields determine chain’s Inverse Kinematic parameters… you do *not* want to change them from default values unless you know much more about IK mechanics than this tutorial can teach you.
What is important to know about models with Hand IK bones
- The plugin doesn’t transform existing hand bones into an IK chain, the way that leg IK bones are organized. Instead, it creates duplicate bones on top of existing ones, keeping originals intact. Thus, you can move your hands *either* by moving your new IK bones or by rotating original hand bones, provided that you don’t get confused about which is which. Particularly, if you have a habit selecting bones by clicking on them in the main screen, you can’t be sure which of two bones residing in the same spot you will get. It’s better to select bones through FMP, making a distinction between original “Arms” and new “ArmIK” bones groups.
- Because of the above, the way your arms move may be somewhat different from what you’re used to. It may be not a big problem when you animate a motion from scratch, but applying pose and motion files made for generic models without IK bones may produce unexpected results. Better keep separate versions of same models with and without IK bones, only using former for projects that are completely your own.
Now put those hands to use!
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