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From: Reusser
Subject: inverse kinematics?
Date: 26 Mar 2001 00:53:12
Message: <3ABED777.E8691764@chorus.net>
Has anyone ever made a pov-ray macro for inverse kinematics?  I've been
working on one for a few days and have managed to get the basics down,
but now I am kind of confused.  I got it to fit two limbs between two
given points, but I'm not quite sure how to go about creating the joints
and limitations.  I was just wondering if anyone had ever made one so I
could get a couple of ideas.

thanks


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From: Ken
Subject: Re: inverse kinematics?
Date: 26 Mar 2001 01:16:31
Message: <3ABEDF57.80E29B8C@pacbell.net>
Reusser wrote:
> 
> Has anyone ever made a pov-ray macro for inverse kinematics?  I've been
> working on one for a few days and have managed to get the basics down,
> but now I am kind of confused.  I got it to fit two limbs between two
> given points, but I'm not quite sure how to go about creating the joints
> and limitations.  I was just wondering if anyone had ever made one so I
> could get a couple of ideas.
> 
> thanks

Check out - http://rsj.mobilixnet.dk/3d/ikn/ikn.html

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/


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From: Rune
Subject: Re: inverse kinematics?
Date: 28 Mar 2001 10:35:59
Message: <3ac204df@news.povray.org>
"Reusser" wrote:
> Has anyone ever made a pov-ray macro for inverse kinematics?

If you're making an long neck-like structure you may find my ikn.inc file
helpful as Ken pointed out.

However, it sounds more like your trying to make an IK leg or arm or
something like that. I have posted a message to povray.binaries.scene-files
some time ago explaining how to do that.

But the message was posted October 24 2000, so you might not have it in your
cache, and I have later found out that it had some bugs in it.

So I have posted a new message to povray.binaries.scene-files. It's called
"How to make an IK leg". Please let me know if you find it helpful!

Rune
--
\ 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 January 28)
/ Also visit http://www.povrayusers.org


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From: Reusser
Subject: Re: inverse kinematics?
Date: 28 Mar 2001 15:11:47
Message: <3AC2455F.D586903A@chorus.net>
Rune wrote:

> So I have posted a new message to povray.binaries.scene-files. It's called
> "How to make an IK leg". Please let me know if you find it helpful!

Thank you very much!  I had the same idea going, but I got confused with the
details of how to rotate the limbs to point in the right direction.  Now that I
know of the vcross and vnormalize functions, I'll be able to get the basics
down without  a bunch of buggy macros.  Thanks again!


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From: Rune
Subject: Re: inverse kinematics?
Date: 28 Mar 2001 15:38:38
Message: <3ac24bce@news.povray.org>
"Reusser" wrote:
> Thank you very much!

Glad you could use it! :)

Rune
--
\ 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 January 28)
/ Also visit http://www.povrayusers.org


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From: Reusser
Subject: Re: inverse kinematics?
Date: 28 Mar 2001 16:55:05
Message: <3AC25D95.1EC64E82@chorus.net>
Rune wrote:

> "Reusser" wrote:
> > Thank you very much!
>
> Glad you could use it! :)
>
> Rune

Thanks again, again, but I did notice one small improvement you could
make.  If you replace the knee direction definition with these lines:

#declare HipAxis       = <1,0,0>
#declare KneeDirection =
vnormalize(vcross(AnklePoint-HipPoint,HipAxis));

you can get a wider range of movement before the whole thing flips or
before you get an error because the knee direction is parallel to the
line between the hip and ankle.


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From: Setepenaset
Subject: Re: inverse kinematics?
Date: 28 Mar 2001 17:15:41
Message: <3ac2628d@news.povray.org>
Thanks Rune! :-)

Sep


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From: Setepenaset
Subject: Re: inverse kinematics?
Date: 28 Mar 2001 17:17:37
Message: <3ac26301@news.povray.org>
Thanks Ruesser!! (what a bountiful day!)

Sep


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From: Rune
Subject: Re: inverse kinematics?
Date: 29 Mar 2001 09:16:53
Message: <3ac343d5$1@news.povray.org>
"Reusser" wrote:
> I did notice one small improvement you could make.
> If you replace the knee direction definition with these lines:
>
> #declare HipAxis       = <1,0,0>
> #declare KneeDirection =
> vnormalize(vcross(AnklePoint-HipPoint,HipAxis));
>
> you can get a wider range of movement before the whole thing
> flips or before you get an error because the knee direction is
> parallel to the line between the hip and ankle.

Are you sure? Have you actually tested it?

Have you considered line 84 in my code:

#declare KneeVector = Perpendiculize(KneeDirection,HipPoint-AnklePoint);

I think it does just about the same thing. If not, please explain further!
:)

Rune
--
\ 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 January 28)
/ Also visit http://www.povrayusers.org


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From: Rune
Subject: Re: inverse kinematics?
Date: 29 Mar 2001 09:16:55
Message: <3ac343d7@news.povray.org>
"Setepenaset" wrote:
> Thanks Rune! :-)

You're welcome - glad you could use it too! :)

Rune
--
\ 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 January 28)
/ Also visit http://www.povrayusers.org


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