#Roll along path…
7 messages in this thread
Hi gang,
Picture this situation: you have a basketball and a circular garbage can. You
are balancing the ball on the rim of the can and moving the can in a flat
circular motion, while the ball balances and rolls around the rim. Now…do
that in 3DS!
I have similar modeling problem (the names of the can and ball were changed to
protect the innocent). Positioning the ball on the rim is, of course, no
problem. It's getting the rotation of the ball right so that it is rolling
around the rim with no slippage.
Has anyone here done this sort of thing before? Any ideas?
Thanks!
-Tyler Colwell
Sierra Analysis Group
Hi Tyler,
<< It's getting the rotation of the ball right so that it is rolling around
the rim with no slippage. >>
I would link the ball to the rim.
Now you can move the rim anywhere you want and the ball is still balanced or
animate the ball on the rim first, then move the rim anywhere you want and the
ball correctly respects it's initial animation.
jonas[adesk]
Thanks for the response, Jonas. The problem is not positioning, but proper
rotation. I have some ideas…
Tyler,
>> balancing the ball on the rim of the can and moving the can in a flat
circular motion, while the ball balances and rolls around the rim <<
sounds like a problem for IK and/or tempo.
>> rolling around the rim with no slippage.
I'd use a dummy in the center of the rim to control position along the rim, and
roll the ball itself for the rolling movement. It would help you greatly if
you calculate the circumference of the ball and rim. Determine how much linear
distance the ball covers along the rim per frame. Compare this to the
circumference of the ball to get the angle per frame of ball rotation. Then
insert keys as necessary to obtain this movement.
– Dave
>>It would help you greatly if you calculate the circumference of the ball and
rim. Determine how much linear distance the ball covers along the rim per
frame. Compare this to the circumference of the ball to get the angle per
frame of ball rotation.
Yeah, I've already done these calculations. I've been trying to avoid linking
the ball for other reasons, but I think it is probably the best option. Trying
to get the rotation correct without linking is a real pain.
Will you be attending Siggraph? I will be bringing a short demo reel and would
like to get some feedback on it from some folks. If so, I look forward to
meeting you and the rest of the Forumites. Or is that Forumians?…
ForumHeads?…
Take Care,
Tyler Colwell
Sierra Analysis Group
>> I've been trying to avoid linking the ball for other reasons…
If linking the ball presents problems elsewhere in the animation, create a
second ball (snapshot) and use hide keys to show whichever ball you need.
>> I look forward to meeting you and the rest of the Forumites.
I will be there and look forward to chatting.
– Dave