POV-Ray : Newsgroups : povray.animations : IK Skeleton : Re: IK Skeleton Server Time
21 Mar 2023 13:22:01 EDT (-0400)
  Re: IK Skeleton  
From: Tail Kinker
Date: 20 Apr 2012 18:13:24
Message: <4f91df84$1@news.povray.org>
On 12-04-20 02:59 AM, robotguy wrote:
> Tail Kinker<the### [at] gmailcom>  wrote:

> I just had a brief look at your work.  You might be interested in a couple other
> projects:
> http://www.magicalrobotics.com/bones.zip
> Alive! at http://www.imagicproductions.com/

Thanks!  I'll check them out.
> I wrote bones.inc (posted the link here in May 2010:
> =50
> ), and I think we've both got different aspects of this problem solved from
> different angles; your work and my work might fit together very well.  For
> instance the base of the torso in a skeleton in bones.inc is called the Zero
> bone and the positions of the hands and feet (really the wrists and heels) can
> be looked up with simple bones.inc macro calls:
> baseOfTorso = getSkeletonPosition (SkelName)
> rightHand = getBoneStart(IndirectBoneLabel("RArm_Hand_Wrist"))
> leftHand = GBS(IBL("LArm_Hand_Wrist"))
> rightFoot = GBS(IBL("RLeg_Foot"))
> leftFoot = GBS(IBL("LLeg_Foot"))

I take it that bones.inc is forward kinesic?

> Using my skeleton data structures, much of the work you have done here could be
> overlaid on top of my base, with the positions of the hands, feet, and lower
> torso (or center of mass) driving macros (later to be attached as a string
> object to the Zero bone) that determine the rest of the joint angles, thus
> generating Poses automatically.  If you check out bones.inc, look at section 4.6
> and 3.2 of the readme file and the way I generated joint angles in the Canfield
> joint demo with the CanfieldCalc() macro.  Animation of skeletons in bones.inc
> is accomplished by interpolating between poses.
> I've been looking for some sort of IK solution for bones.inc to generate poses,
> and I think you've got it.  Have a look at the readme file in bones.zip and tell
> me what you think.  The BipedRobot file will give you a good bones.inc bipedal
> skeleton to work with if you want to try messing around with adding your IK work
> to my Poses and interpolations.

I'll do that, when I get a few free moments.  :)

> I'm thinking about ways to incorporate a converter program between blobman and
> bones.inc, so existing blobman characters can be overlaid on bones.inc
> skeletons, have poses generated by your IK functions attached to Zero bones, and
> then animated via the InterpolatePose() macro in bones.inc.  That way existing
> blobman work can be re-used and much more easily animated.

Blobman parts could be separated out and attached to my ik_skeleton 
fairly easily - I actually wrote ik_skeleton with that in mind. 
Unfortunately, I haven't got it working yet, as the blobman parts are 
oriented differently than ik_skeleton wants.

> Several skeletons can be animated at once with bones.inc, and they don't need to
> be bipedal - could be dragons or spiders or snakes.  Your IK stuff could be
> applied to these types of skeletons as well.  This could be very useful for lots
> of people.

I'll compare the two and think about what can be done.  I need to do 
some re-work on ik_skeleton again, anyway, due to issues with some of 
the joints.  Especially, I want to be able to solve three segments per 
limb, instead of only two, possibly with an adjustable bias between 
joints, so that digitigrade skeletons can be built.  I also want some 
ready-made macros for walking, running, jumping, etc., with 
interpolation between movement styles.  (That's getting into hurty math, 

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