Subject: Re: Inverse Kinematics
From: [email-masked] (Jonathon Bowman)
To: Multiple recipients of list <[email-masked]>
Date: Mon, 11 Dec 1995 16:48:07 -0500

>
>
>I am creating a robot model that is roughly humanoid in shape that I would
>like to use IK with but I've never used IK.  Is it hard to set up?
>
        I'm pretty much a beginner like yourself.  I've been using Lightwave
for about 2 months, and I just set up my first Lightwave IK character last
night.

        It actually isn't that tough.. (it took me about 3 hours to get the
whole thing set up with IK - hierarchies, rotational limits, and targets).
Overall, the process is pretty easy, but there are some stumbling blocks
that you should watch out for.  

        First, always make sure that you put a null object at the end of
your IK chain, or else IK will not work properly.  (Example:  in a chain
consisting of an upper leg parented to the torso, a lower leg parented to
the upper leg, and a foot parented to the lower leg, you would put a null
object at the end of the foot.)  This is because when using IK goals, the
object with the goal will try and point it's origin towards that goal, and
the origin is the rotation point.  So in order for IK to work, you must have
that null object there.  I hope that made sense.

        Secondly, the thing that had me confused for a while was the fact
that when you set your min. and max. rotational limits, the min. must be
less than the max. and vice-versa or else lightwave will automatically
adjust the incorrect one to the same value as the other one, and the object
will not be able to rotate along that channel.  You have to watch out for
this when setting your limits.  Once again, I hope that made sense.

        Anyways, good luck getting your first IK chain working.  I know the
results that I got were well worht the effort.

        Ciao,
                Blacky

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