I’ve migrated from commercial programs over to blender with a decent level of success. I’ve figured out a lot of tricks in the rigging system, already, but so far I can’t find a really elegant way of rigging an independent hip. The setup would need to allow the hip free movement without affecting the placement of the head/shoulders. Now, normally I’d have the hip setup and the top of the spine as children of the same base bone behind the hips with an IK setup for the spine (even though I hate IK spines), so I could move them together, or independently if I wished. I can’t find a good constraint setup, though, so the shoulders are far too free with their movement and can’t be constrained within some kind of distance to the hips to keep the shoulders from going farther than they should.
Can anybody think of a clever way of doing this in blender? I’d love it if FK could be involved for the spine, but so far I’m not seeing how IK/FK switching is possible in blender without doing dual-rig setups (which I might do >_<). I may just do my little ghetto hack setup if something elegant can’t be found. =) It would just require a lot of care so that the spine wouldn’t separate from the shoulders, which isn’t something I want to worry about when I’m animating.
Now, normally I’d have the hip setup and the top of the spine as children of the same base bone behind the hips with an IK setup for the spine (even though I hate IK spines), so I could move them together, or independently if I wished.
Why not just do this? I’m not sure I see the problem. You can parent bones to others without connecting them.
I’d love it if FK could be involved for the spine, but so far I’m not seeing how IK/FK switching is possible in
The IK constraint has an influence slider that can be animated (hit “key”). 1 is fully IK, 0 is fully FK.
If i just set up an IK chain for the spine, I can’t have both the shoulders and the hips on the same level of the heirarchy, or the entire thing freaks out. I could use empties to achieve the same effect, but I heard using empties in your rigs may cause a few issues with NLA stuff. It may also be that I haven’t figured out all the intricate things in the rigging system, either. The rigging system is very capable…it just seems to have a lot of very off behaviors as default. I’ll figure something out, i’m sure.
As far as the IK/FK thing, I’m aware of the influece settings, but would there be a way to key multiple of those at once with a single key such as in maya? I know I’ll never use it if I have to go into each of the bones and key them on and off, again.
Well, you’d only have do it on the end of the chain. So in a normal bipedal character, you’d have one for each arm and possibly one for the spine (I like FK spines, so I wouldn’t have that one). You could opt to create them for the legs too, so 4-5 switches total.
As for separating hips and shoulder, it comes down to creating invisible bones to which the other chains are parented. I’ll show you the legs and maybe it’ll lead you to your own legs / shoulders solution.
To control the position of the pelvis I start with a root bone. From that bone I extrude two from the tip, one pointing up (spine), and one pointing straight ahead (pelvis).
Next, create legs. I’m going to do that by extruding from the pelvis bone.
Click the hip bone, hit Alt+P (clear parent). Move it and the rest of the leg back so that it’s aligned to the root bone’s tip.
Add an IK null bone to the foot. Select the ankle joint and do Add->Bone. (Don’t extrude.)
Copy, paste, and flip the leg bones to the other side. I like to select the root bone’s tip, snap the cursor to it, and then scale a duped copy of the legs around the cursor by x = -1.
Add IK constraints. In pose mode, select the IK Null bone, then the lower leg bone, and hit CTRL+I. Under the constraint’s settings change the chain length to 2 (don’t include the hips). Do this for both legs.
Now, at the moment if you’ve followed everything the hips aren’t parented to anything. (Try moving one and see – only the leg should move.) Next up is separating them from the root, but allowing the root to move them. Copy and paste the Pelvis bone. Name the original Pelvis Control, and the copy Pelvis. Don’t move it. If you switch to B-Bones view mode on the armature and hit Alt+S, you can scale the control bone’s size up so that you can more easily select the two.
Now, Pelvis-Control should still be parented to Root, and Pelvis shouldn’t be parented to anything. Next, select each hip, then Pelvis, and parent the hips to the pelvis bone. Remember to choose “Keep Offset.” If you rotate the pelvis bone in pose mode now, both legs should dance.
Finally, give the pelvis bone a Copy Location constraint. Copy the location of Pelvis-Control, then hide Pelvis Control. Now, you can move the root bone, which moves the pelvis, but you can rotate the pelvis independently of the spine bone.
That should be enough to lead you on the way to doing something similar with the shoulders. You’ll need a modification or two to get the IK spine in there and working also, but it’s not too difficult.
I did all the above because it took me ages to figure this one out. Hope this helps.
I didn’t really look at the rig above, but as I understood from the Jeff Lew DVD, you can move the shoulders and hips independantly if you parent the shoulder and hips to an empty (or bone). Constrain it to them. Like he said, a constrain can exist outside a hierachy, thus enabling you to move stuff freely in your bone hierachy. You should check out http://www.jefflew.com, he has released some free chapters of his DVD there.
this is what I’m using at the moment, shoulders limited in x & z and locked in y. Parented to a loose control bone, so you can hunch the shoulders forward, up down etc while retaining individual movement, you never know :), this is then parented to the neck/spine controller.
Right, this is what I first mentioned. It’s just a very inelegant method, as you can easily just break your shoulders from your spine and have it move in ways it should. Sure, it’s not a big deal to avoid doing that sort of thing, but I’ve made rigs in other software that didn’t suffer from that, and could keep the functionality of an FK spine, it’s just been a long time and I no longer have most of those files laying around to check out how I did things.
Zenitor, however, a few of your ideas in there intrigue me. Thanks for the ideas. =D
kattkieru, too, you’ve got a different workflow than I, but I appreciate your information, and it definitely doesn’t hurt to see your method. =)
It’s not inelegant at all… Actually, extending on what I posted above you could easily keep the shoulders in whatever position you wanted… I guess at this point I’m terribly confused about what you’re actually asking. (I especially didn’t understand the underlined part of your quote.) Can you do a few screen shots of your issue, and describe it as you go along? You talked of wanting to constraint the shoulders so that they don’t move past a certain distance from the hips?
Thank you for <insert a praising adjective here> work!