--
Thomas Bates

"NOTHING GREAT WAS EVER ACHIEVED WITHOUT ENTHUSIASM" - EMERSON
"Rune" <run### [at] runevisioncom> wrote in message news:3dd11ab2@news.povray.org...
> Tom Bates wrote:
> > Very early stages of my (hopefully) upcoming IRTC entry.
>
> Looks promising!

Thank you.

>
> > My next task is to figure out where to place the
> > hands & feet to make him walk and run.
> >
> > I have some ideas to start with, but I still have
> > some snags.
> >
> > Any suggestions?
> >
> > Rune?
>
> Hmm, what exactly are you having problems with? I'm not sure what kind
> of suggestions you're after.
>
>
> Rune

My IK macro takes position and orientation of the body, the direction of the knee,
the position of the heel, and the orientation of the foot, all in world coordinates.
My macro gives me back the rotations for the hip, knee, and ankle, all in coordinates
local to the appropriate joint.  It does this very well (IMHO).

My main problem is trying to figure out how to specify the foot positions for a
realistic walking cycle.

From observations, I've roughly mapped the path that the heel takes in a basic
walking cycle.  However, If I'm a little bit off, as the heel is lifting off the
ground as the step begins, then the toe may slip along the ground.  On the other
hand, if I specify the toe position, and calculate the heel position from it, then
when the heel hits the ground before the toe does, it may slip along the ground.
Also, when the foot is traveling through the air between steps, it's not so critical
that the heel and toe positions are specified precisely (so long as they don't make
ruts in the track).

The solution that I've been considering is weighting the specification of the heel
and toe based on the time position in the walk cycle.  That is, specifying that at
THIS time, the heel position is the most important, but at THIS time, the toe
position is most important, and at THESE times, neither are that important.  However,
that solution is only in my mind so far since I haven't spent the time yet to work
out the specifics and try it out.

From reading your notes at your site, it seems that you had a similar challenge, but
found a reasonable solution to it.  I'm interested to learn what solution you came up
with for Al.

Tom Bates

--
#macro T(B)#local m=mod(B,8);#local B=floor(B/8);m#end#local C=126981491245202;#
local D=115694168992822;sphere_sweep{b_spline 16#local i=0;#while(i<16)<T(C)-4,T
(D)-4,10-i/10>.1#local i=i+1;#end pigment{rgb 1}}light_source{-10,1} //Tom Bates

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