[x3d-public] Joe, question about H-Anim

[Joe D Williams]

----- Original Message ----- 
From: "John Carlson" <yottzumm at gmail.com>
To: "Joe D Williams" <joedwil at earthlink.net>
Cc: <x3d-public at web3d.org>
Sent: Friday, February 19, 2016 9:06 PM
Subject: Joe, question about H-Anim


> Joe,

Hi

> Does H-Anim have the concept of 1) Geometry stretching between two 
> Transforms (like a stretchable bone between two joints)?

All HAnim animation is intended to be by Joint rotation. In general, 
we only change the position of the root Joint, which moves the entire 
model. You are thinking of changing one or more Joint center(s) 
directly and having the intervening geometery arrange itself to stay 
connected. I have not seen changing the Joint center directly work as 
you describe and is not taken care of automagically. You can make 
anything out of Joint and Segment hierarchies, even a hair, but the 
Segment lengths remain fixed. I have a good (best ever X3D HAnim ever 
published) HAnin model for experiments.

> The transforms may contain further geometry.

Yes, a Joint, which contains a Segment containing some geometry and 
the next Joint. The Segment geomety may start at the parent Joint 
center and end at the next child Joint center. The Joint centers 
really don't know anything about the Segment geometry coordinates, or 
vice-versa. You rotate a Joint then the child hierarchy follows.

> See other thread Leonard and I are on.  This would be used to 
> implement a graph, but unlike H-anim in that it might allow for 
> cycles or perhaps just DAGs instead of hierarchies.   What are the 
> physical implications and coding implementations of such cycles or 
> DAGs?

more thought needed here. For what you describe you may not need a 
hierarchy that actually connects something from point to point. Sure 
you could build something really clever to draw nD graphs since once 
you know the points it is fairly easy to draw some connecing geometry 
so why not just compute and draw the points and connecting lines each 
frame?

> Could we use H-Anim-like physicality to implement force directed 
> graphs?

Try rigid body nodes, there may end up to be some stretchy stuff 
there.

> On the web?

Why not? Hopefully, may depend upon computing needed.
I have not yet tried my humanoid models in X3DOM for some reason.

some segment geometry and skin examples in here:

http://www.hypermultimedia.com/x3d/hanim/HAnimCollection20130818/HAnimCollection20130818.zip

and skin here:

http://www.hypermultimedia.com/x3d/hanim/JoeH-AnimKick1a.x3dv

I thought of using a scale to change length of Segment and then a 
Displacer to move points of the geometry but I don't think that would 
work well. For example it is fairly easy to do hanim with Joint 
rotations and child Segment geometry but gets much more complex when 
you need to deform skin according to Joint rotations.

Also, I think Don showed a way to draw the initial endpoints of 
Segment geometry by finding the parent and peer Joint centers by 
reading the initial Joint center values. For standard HAnim it works 
like our bodies and except for demo of things breaking does not deal 
with changing Joint centers directly or Segment coordinates directly 
since it is all done by controlling Joint rotations in the hierarchy.

> John=

Thanks and Best,
Joe

> > It is important to recognize that the h-anim character we have is 
> > of World Standard Quality. We need to add some features, like some 
> > 'standard' skins, more named skin surface feature details, and 
> > representative locations of internal organs, but the basic model 
> > of joints, segments, and skin is all there now and all works in a 
> > couple of X3D browsers.

Literally, anyone that says we do not have a top-notch humanoid model 
with all basic features provided by the the most expensive humanoid 
modeling tool does not comprehend the basics of those high-end tools 
and/or does not understand the feature set of X3D HAnim.