Date: Wed, 21 Jan 1998 10:44:59 EST From: PowerRoy Subject: [IML] IFW: Bones, IK, and Child Objects ... Howdy Y'all, I've been working on my first "Bones" project in Imagine (for Windows 1.3.4), and came across a little problem that I'm hoping someone may have a solution or work-around for... Awhile back it was mentioned on the list that there is a problem with "boned" CHILD objects not updating correctly when the bones are posed. Accordingly, I built my character as one object, with the exception of the eyeballs and spectacles. I figured that since these were child objects withOUT bones, that things would work O.K. ... and they do, if I pose the character by selecting one bone axis at a time, and rotating it into place (for instance, if I bend the upper body, then do a "bones update", everything comes out where it should). But last night I thought that I would give Inverse Kinematics a whirl, and discovered that these child objects do not update when using IK ... if I set up constraints, and then bend the upperbody by, say, grabbing the wrist and moving it, the head will follow along with the bend of the upperbody -- but the eyeballs and spectacles stay where they started, and don't follow along with the head (producing a pretty freaky looking character). Has anybody else come across this little problem, and possibly come up with an elegant (and hopefully simple) solution? --------------------------------- Date: Wed, 21 Jan 1998 20:22:44 +0400 From: Charles Blaquiere Roy, if nobody else comes up with a solution for you, I may have a workaround. My knowledge of bones is extremely limited (BVRE doesn't do bones yet %^S), but how about the following: bone your eyes (sounds painful!), but set up the subgroups so the eyes only move, but don't stretch. If all your other boned objects update correctly, then the eyes should too. --------------------------------- Date: Wed, 21 Jan 1998 13:57:52 -0800 From: Clae & Deborah Tanett Clae here This is very curious to me... Where do you have your 'eyeballs' attached? (sorry for the phrasing :)) If they are parented to the last axis in the neck line they would move as you moved the rest of the axises, the body would update to their position not them to the body's. It's really hard to say what the problem is without knowing to 'what' the eyes are parented to. --------------------------------- Date: Thu, 22 Jan 1998 19:58:57 -0600 From: Mike Bayona The only thing that occured to me, is that to setup bones, you have to group the axises in a proper heirarchy, but, you might have grouped the seperate objects, the eyes/glasses, to the parent object, or to the wrong bones, hence they aren't moving with the head bone. --------------------------------- Date: Thu, 22 Jan 1998 22:26:34 EST From: PowerRoy To Clae and Charles, (Clae wrote ...) <> You're absolutely right, Clae ... I'm glad you confirmed that things SHOULD work the way I expected them to (and yes, they are parented to the last axis in the neck). You gave me good reason to go and re-examine what I was trying to do, and I found my mistake (and fixed it). It seems that I had messed up in defining the bones subgroups from the upper back on up through the character's head. It turned out that the eyes and spectacles WERE updating correctly, but the HEAD wasn't, and (since bones are still kinda new to me), I misinterpreted what I was seeing (well, it was getting pretty late at night when I noticed that I had a problem). Thanx for your comment, Clae ... ya helped me get my Santa Claus working much better with IK than it was before (the back "bones" were working, and the neck "bones" too, ... except for just one of 'em). Thanx again. (and Charles wrote ...) <> Before I tracked down my problem (thanks to Clae), that was gonna be my solution, too. I had already used this same technique with the hands and boots, which were originally seperate objects (until I found out that boned child objects don't update correctly). So I had joined them to the main body, and defined each as a distinct "bone", which uses the same face subgroups for both large and small subgroups. Neat trick, and it works pretty well. Thanks for the assist, and keep an eye out for the animation (if I EVER get it done!). --------------------------------- Date: Fri, 23 Jan 1998 01:30:42 -0500 From: Collins One thing I haven't seen mentioned yet... Did you add the eyes and glasses before, or, after you created any states? If it is after, you will get the results you are talking about. I know if you have created a bunch of states, this will sound cruel, but, if you strip your object of all state data and start over with a new default and go from there, it will work properly. Or, You could update the default, then set the parent object the next state and move the non-conforming object to the proper position, then update that state, and so on for the rest of your states... I believe this works also. --------------------------------- Date: Sat, 14 Feb 1998 23:12:23 +0000 From: George Cole Subject: [IML] QUEST: Bones Hi again. I've followed a bones tutorial found in the FAQ 8 but I can't seem to get it to work for me. Basically I've got a cube with 12 faces (2 triangles per square side). I then fractured 4 of the sides (not the two end sides). This cut each side into 8 faces. I would explain this with ASCII art but Im no good at it :-). Think of it as a robot arm. The two unfractured ends are the wrist and the shoulder. Inbetween I have created an Elbow by fracturing. I select the wrist end faces and save it as "small" subgroup. I then select the wrist end faces and all the faces up to and including the elbow and save them as "big" subgroup. I then add an axis and place it at the elbow with the z axis facing the wrist. I group it to the object axis with the object axis as the parent. I then select the child axis and set subgroups correspondingly (small as small subgroup and large as large subgroup). I then select the child axis in object mode and rotate it. I then select the parent axis in group and/or object mode and select "update bone shape (or something)" but nothing happens!! Could some-one please point out to me what I'm doing wrong. The tutorial I followed worked fine and I thought I'd done everything right in this one as well but obviously I haven't. Thanks, ---------------------------------- Date: Mon, 16 Feb 1998 10:57:46 +0000 From: Richard Gowland George, I've had a problem with bones that sounds like the one you've got. In the end it turned out that to get the bones to work I had to select shape and grouping when creating the default state. If you are still having problems there are some rules to bones in Imagine at this site: http://ourworld.compuserve.com/homepages/crestline/bones.htm I hope this is of some help ---------------------------------- FYI: Clae Tannet has a Bones tutorial on his homepage at http://www.accutek.com/~cd. I don't visited it yet.