character carrying an object- (child of ) issue

hello.
I use “child of” to attach an object to hand bone of my character.Purpose is character to carry object in two hands (over its head i. e.). How to make : other hand (i.e. right one) keep its place on the carried object?? I try various set up ,but have no satisfactory result. In tutorials I have seen (i.e. : http://cgcookie.com/blender/2011/08/22/animating-a-character-picking-up-an-object/ ), no reference to such siituation. thx

First, I assume the other hand is set up with an IK constraint.
Once that is done, just make both the object and the hand IK a child-of the same handbone

there is the problem. I tried to do it this way,but in this case ik doesn,t work. Hand bone and hand try to follow the object moved by other hand,but its ik chain doesn,t work…only hand bone rotate following carried object, arm and upper arm bones doesn,t move…

:frowning: I can play with camara ofcourse and show only one hand ,and other one move more or less corectly behind the object, but I hope there is some better way …

sounds like you don’t have the IK set up properly. Look into that

this rig is very smple, ik in forearms, no target,just chain length.
I added to the carried object bone two “child of” , one for left hand and one for right hand bone,and any one works fine , that means ,when I grab left forehand,object follows it as it should be(while rigt hand stay in it position),and if I grab right one,same (inversely)…but if I grab both forearms at a time,then object movs excessively,and loos contact with hands again. Set influence in every “child of” at 0.5 is not solution.

post a blend file

childOFissue.blend (543 KB)
thats just an exemple created in 2 minuts,but is this same scheme. THX

Like I said, your IK set up is the problem. Look up IK constraints on Youtube.

Here is a ‘fixed’ blend

childOFissue.blend (543 KB)

thank you very much , daren. SOlved

Here’s the way I normally do this… (the Darren fix however was cool) but I hate using the Child of Constraint… I always have problems with it… so heres a different way… (perhaps a bit more complex)

[ATTACH]213972[/ATTACH]

anywayz more than one way to skin a cat…

thank you norvman,your construction is also nice. So…if anybody use other construction,please, show it here .

I would skin the OPs particular cat by constraining BOTH IK hands to the object rather than constraining the object to the bones this should let you move it a little easier with a more pleasing result, same go’s for swords, guns, teacups, and just about anything… it just makes animating easier imo…

but If you’re finicky about using an “all armature” based animation, create a new unparented bone for the prop, parent the prop to it, and use this as the props handle, then you should be able to “child of” the hands to this “prop” bone as long as its not parented to anything in the IK chain.
the only time I would usually parent the object to the armature is… for example having a gun in a holster, or a sword in an… ummmm whats the word… lets say “sword holster” or a pen behind a characters ear. this way they hold position well. but as soon as the character grabs said prop , i would parent the hands to it… for ease of animating…

try both ways… parented object, or parented bone, and see which you find easiest

like norvman says … there are a few different ways of doing this

Only thing I can would continue to point out is that the “child of” constraint seems to be an older piece of code… and the “copy Transforms” constraint is sort of it’s replacement… so use that… (this what I have heard via the grape vine on this) and I have experienced some goofy problems when using “child of” that went away when I started using “copy transform”…

You are right… So,probably that should look as below( move the bigest bone inside the ball ,and to keyframe the hands independly form ball ,after they ,i.e. separate …use I key influence in const. “copy transform” to 0 ,and then you can again use ik bones to move the hands(-info for noobs like me or worst :wink: ) :
childOFissue1D.blend (565 KB) (this is file with animated influence of copy transform const.)
( if other “noob” need it…)
So…thank you very much again… (I regain faith in blender :slight_smile: )

Attachments

childOFissue1C.blend (547 KB)

There yah go… Nice work Kuku!!

Thank you.
One question more… I find very hard to reposiition hands after I-key this const to 0 .So in frame X I-key 1.0 , then in frame X+1 I-key 0 value. In this moment the hand jump out,and I have to position it in same pose as it was in previous frame. with all this hand IK bones that is very hard work. Is there any way to avoid this obstacle???(I mean -something more than manual position using ghost bone option :slight_smile: )

Try using Apply Visual Transform (search for it with the spacebar menu) with the modifier at 1.000 influence.

Having taken a second look at your childOFissue1C.blend file… I was going to critique on the Rotation angles of your bones not being aligned properly… (which in a lot of instances can cause bone jumping/poping)… however in this case I think you can fix this preticular file without having to mess with that… it looks to me like you just simply need to set key frames for your Hand Ik bones in the proper places… That is have a the Hand perfectly aligned with the hand target on the ball and Key frame it in ‘Location’ when ever you also Key frame the copy Transform Influence…

Easiest way to do this in this case is go to the frame where you have your Copy trans influence keyed and select the contact bone on the ball … (objectbone.L) then Shift+S > Cursor to selected… then pick the IK hand bone (IKPTR.L) and Shift+S > Selection to Cursor … then ‘I’ (eye key) (for save keyframe) > location… and that should do it…