Rune wrote:

> Are you sure? Have you actually tested it?
>
> Have you considered line 84 in my code:
>
> #declare KneeVector = Perpendiculize(KneeDirection,HipPoint-AnklePoint);

My idea was actually due to trial and error before I saw line 84, but it
still fixed the error I had when I bent the leg too far back.  When the leg
was too far back, the whole leg would flip over or give me an error if the
ankle and the hip had the same y-coord.:  shin -> \/ <-thigh.

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"Reusser" wrote:
> My idea was actually due to trial and error before I saw
> line 84, but it still fixed the error I had when I bent the
> leg too far back.  When the leg was too far back, the whole
> leg would flip over or give me an error if the ankle and the
> hip had the same y-coord.:  shin -> \/ <-thigh.

That's because the KneeDirection have to be adjusted to fit the leg.
If the leg is like this:  shin -> \/ <-thigh.
Then the knee points downwards and thus the KneeDirection must point
downwards too. The code adjusts the KneeDirection pretty much, but it can't
read your mind - you have to tell it roughly in which direction you want the
knee to point! :)

With your method the KneeDirection is calculated automatically, but then you
just have to specify a HipAxis instead. It's not a better or worse solution,
just a different approach. Personally I find it more intuitive to specify
the KneeDirection than to specify the HipAxis.

Rune
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Rune wrote:

> That's because the KneeDirection have to be adjusted to fit the leg.
> If the leg is like this:  shin -> \/ <-thigh.
> Then the knee points downwards and thus the KneeDirection must point
> downwards too. The code adjusts the KneeDirection pretty much, but it can't
> read your mind - you have to tell it roughly in which direction you want the
> knee to point! :)
>
> With your method the KneeDirection is calculated automatically, but then you
> just have to specify a HipAxis instead. It's not a better or worse solution,
> just a different approach. Personally I find it more intuitive to specify
> the KneeDirection than to specify the HipAxis.

I agree completely, but I just found it to be a little easier with animations
when the knee direction changes and you can just let the computer do the work
instead of manually changing the direction.

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"Reusser" wrote:
> I agree completely, but I just found it to be a little easier
> with animations when the knee direction changes and you can
> just let the computer do the work instead of manually changing
> the direction.

I think perhaps generally it is easier to use the HipAxis method when the
leg movement is confined to a single plane, while with more free movements
the manual KneeDirection is more intuitive. Just a thought.

By the way, I have uploaded the scene file to my website for future
reference. (Questions like yours come up once in a while...)

http://rsj.mobilixnet.dk/3d/goodies/goodies.html

Rune
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\ Include files, tutorials, 3D images, raytracing jokes,
/ The POV Desktop Theme, and The POV-Ray Logo Contest can
\ all be found at http://rsj.mobilixnet.dk (updated March 29)
/ Also visit http://www.povrayusers.org

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