Subject: Bones and stuff
Date: Thu, 26 May 94 18:12:40 CDT
From: setzer@comm.mot.com (Thomas Setzer)

Mike H. sent this to me.  I thought it had some useful info about bones...


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Tom,
	BOnes will do the flag thing as well as a jelly fish and almost anything
that you can think up ( i resisted the standard "anything you can imagine")/

	It seems that people dont get the really simple thing with bones.

	The small part of the bones or small subgroup is the part that will be
the least affected by the bending of the object, the large part of the bones
defines the area that is the total amount of trinagles that will bend.  THE area

between the two is the place where there will be the most compression or
decompression of the trinangles as the morph occurs. 

	THe hand.bon object shows that when you deal with the whole finger, the
big subgroup of the finger is the whole finger and the next subgroup for that
bone at the bottom of the finger includes all of the trinagles just above the
area that you would say in the joint of the finger or the first knucle.

	As you use this in other ways you will have to think about how to place
the bones properly and what sub groups to assing to what bones.  You can overlap

them its fine, but as you said you might get wierd results if there is too much
overlap.

	I have been having a great time making faces and then making them "talk"
or express some form of emotion, the bones are all over the face, the more I put

and the more I assing better groups to the bones the more life like it becomes.

	Because Imagine only uses trinagles you will not get things busting up or
distorting, this is aproblem with programs that use (n) sided polygons, here the

area distorts and looks terrible whenanimated.

	There are of course other techniques used for different things like flag
waving, use the deform tool, set different states and just do a simple morph,
you will need more morph targets but the results can be better than bones.

	Finally, bones was intended for animating characters, it has more work to
be done on it to make it more friendly, like AUTO BONE, which will try an figure

out what to do so you dont have to, but then we also want Precognative Ray
Tracing, so all you have to do is think it and it goes directly to a VCR for
viewing,  Now that will be a great set of code.

	HOpe that helps.,


	Mike



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