In article <3a6190cf@news.povray.org>, "Rune" <run### [at] inamecom> 
wrote:

> > Yes, but much less than a bone ID and weight per vertex.
> 
> But isn't that what we're talking about? I mean, sure optimisations 
> could be done, but we're talking about a bone ID and weight per 
> vertex, as opposed to field-based weights, right?

But the bone ID and weight can be packaged into one piece of 
information. The vast majority of vertices will belong to a single bone 
and use the same weight, so the bone-ID/weight pairs can be kept in an 
array (with no duplicates) and accessed with ID numbers, so all you have 
to store per-vertex is a couble data-ID numbers (usually one, only more 
than one ID when multiple bones influence the vertex), and separately an 
array of bones, and an array of bone-ID/weight pairs. The total memory 
usage for an ordinary use of this feature will be far less than a list 
of bone-ID/weight pairs for each vertex.


> > True, it isn't as bad as I had thought...
> 
> What? When? Why?

I had been thinking there would be problems when the bone fields moved 
and intersected each other, but they wouldn't...


> > I think this would be needed to do joints correctly anyway...
> > when you rotate your arm, your elbow doesn't slide like a
> > ball joint, your whole upper arm twists around the bone.
> 
> As I said earlier. :)
> 
> "That's because in reality when we twist our limbs (for example
> our wrist), the twisting actually occurs along the whole limb
> and not just at the joints."

Hey, it was late, I was tired. :-)


> > (maybe non-unit length to indicate some weighting value?),
> 
> No, those two things have little to do with each other, so I think 
> it's not a good idea.

After more thought, this value wouldn't be necessary...


> > or a position vector indicating a point next to the bone?
> 
> This is basically the same as the unit-length idea isn't it? I go for 
> unit lengths.

One could be calculated from the other, the same information is being 
specified, but one might be easier to use than the other. Don't want 
people forced to use macros so they can input the data the way they 
want...but unit-length vectors seem to make more sense.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

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