Hello, folks!

I'm trying to make a simple animation (well, simple in my eyes, anyway).  I want a character to be holding a cup, then bring it to his mouth and have the cup and hand attach to the head for a short bit to simulate drinking from the cup, then returning the cup to the original position.  My idea was the following:

Parent the cup to the hand (in this case, the right hand).  Animate the cup being lifted to the mouth, using forward kinematics on the hand.  At the frame where the cup contacts the mouth, add a constraint, and flip over to IK.  This does have the effect I want to use (where the cup is lifted to the mouth and then "stuck" to the mouth for the duration of the drinking part so I can move the head and have the hand and cup move with it), but the problem becomes transitioning between 0 constraint and 1 constraint.

At the "1" value, the wrist of the character breaks and the joint looks crushed.  I have tried rotating the constraint grouping but I can't get the joint "uncrushed".  And, if I transition between 0 and 1 values, the hand rotates incorrectly.

I know I'm doing SOMETHING wrong here but I can't imagine what it is.  If anyone has some pointers as to how to do this animation better, I'd be greatly appreciative!  The idea I want is the character to be holding the cup on a table, then lifting the cup to his mouth, drinking while his head is in motion, then returning the cup to the table.

Thanks in advance!

Personally, I wouldn't change the constraint. I'd leave the cup attached to the hand, never to the head. This accurately reflects what is really happening (a cup is always held by the hand, never your lips, and if you walk, your lips move against the cup).

Without seeing the animation, I can't imagine what the problem is... maybe the position of the head is creating a pose that Poser messes up when IK is turned to 1. I've seen plenty of frames where IK has decided to rotate hands and feet 120 degrees or so... pointing off in all sorts of odd ways.

I would not change the parenting either.  I doubt i would use IK either.

Parent the cup to hand and then move the hand to the required position.

That's what I did originally.  But for this animation, I need the head to turn while the cup is on the lips.  Therefore, I need the cup to "stick" to the head, otherwise it'll be nearly impossible to have the cup not drift around on the lips.  This would be the same if the character was trying to facepalm (a hand touching the face, then the hand moving with the head), hands on hips (hands moving to the hip, then moving with the hip), hand adjusting a watch (grabbing the watch on the other wrist and then moving with the other wrist) or other similar types of actions.

Here's what I'm trying to do.

https://www.youtube.com/watch?v=CtemiW4PH8k

Please don't critique the posing or animation; this is merely a very rough test animation, but this is essentially identical to my actual animation.  I want to be able to to have him lift the cup to his mouth, then move his head as the cup is connected to the mouth, then return the cup to its original position without the wrist, shoulder, or hand wigging out.

Thanks!

Yep, understand what you are trying to do, and I'll restate my original post.

First, try it for real. Pick up a cup and mimic the action you want to animate. The only reason the cup stays in position is because your hand pushes the cup against your lips, and when people move, they purse their lips to act as a cushion against the cup so they don't hit their teeth.

Now, break your scene down into it's stages. For one, I'd try parenting the cup to the specific finger (say middle 1) as that is where the true mass of the cup would be rotated from.

Next, make a pose where the cup is at his lips.

Finally, make a pose where the cup is at the lips but the head is turned. Aim for the cup to be about 6mm 1/4 inch away from his face at the end. Your last frame.

Next, go from origin to pose 1 as a keyframe about 2/3rds of the way through your total frame count. At 30 frames per second, about frame 60.

Then from around frame 75 or 80 enter the same keyframe/pose. That should hold him in position to take a sip.

Go to frame 110 or so, enter your last pose.

If the general motion is fluid, go back and tweak frames. Especially the last 30 or so, where the cup is against his lips. Track the cup, adjust his expression to purse the lips against the edge of the cup.

You should never need to change the constraints. Stay with the cup attached to the hand. His hand holds the cup, his face does not. Move the shoulder and collar joints to adjust position.

I find if I try to do it that way, the cup unrealistically drifts on his mouth.  At the point where the cup is on the mouth, the head is essentially "driving" the action for that portion.  In real life, when I put a cup to my mouth and then turn my head, I can feel my head pulling or pushing on the cup, which moves my hand.  Both the hand and the mouth are driving the motion of the cup.

No, what you feel is the cup pulling on your lips, feeding spatial information to your brain then to your arm. The cup is NEVER under the control of your head, only ever the hand. Your hand pushes the cup against your lips, your lips push back to keep it from hitting your teeth. The cup is never truly stationary against your lips, it is always moving a little, and this feeds back positional corrections to your arm and hand to keep it in position. If it was truly the way you describe, there would never be a reason to dribble while you drink when tilting your head, and that is plainly not the case. People dribble. If you have 'unrealistic drift' that is because you haven't tweaked the frame well enough.

Alrighty, I'll try that.  Thanks for your help and I apologize if there was any stubbornness on my part.

All good ;-)

I did a quick test using my recommended method. Looks a bit suspect without a cup, but you get the basic idea. I kept the res really low for several reasons; speed, small bandwidth on the upload, plus you see the action as a whole as you cannot focus on details (there aren't any!).