"Chris B" <nom### [at] nomailcom> wrote:
> "melo" <mel### [at] coxnet> wrote in message
> news:web.47db0e5f3d86ff96314b3d800@news.povray.org...
> >
> > How I wish POV-RAY had allowed some kind of structure and linked list
> > definitions, how I wish it had known and informed its users about states.
> >
>
> I suspect that it would be difficult to meaningfully interpret the internal
> structures and the rotational and positional information used internally by
> POV-Ray. You'd need to know the starting point that this information is
> relative to, and this may not be easy to determine or what you may expect in
> all situations.
>
> What POV-Ray does provide is a series of macros that enable you to apply
> transformations to vectors. You can therefore say, "if this is my starting
> point, where would it end up when I apply these transformations?". IMO this
> is more productive and easier to use.

Your statements highlighted a lot more that I had made assumptions on.  Meaning,
I had assumed that, the documentations on POV-RAY would have enabled me to
interpret the internal structures.  Yet another assumption I had made is that,
those internal structures are state aware.  Meaning, during animation, if I am
in "frame_number=x"  the internal structures would correspond to all the
code parsed, executed for that particular frame number.

As I had mentioned before, in my crude, 1st skeletal animation attempt, I had
povided joint rotation vectors with respect to a global coordinate system, not
in relation to parent joint-segment pairs.   And I had utilized
             Rotate_Around_Trans(Rotation, Point)
macro.

With your help so far, I had managed to get him move from Key-Frame(=Pose) to
Key-Frame(=Pose).  I give him 5 frames to move from one Key-Frame to next.

Well now that I put him in a room, I could see the short-comings of my approach.

Obviously remembering his previous Pose when the new Pose began was not good
enough.  In addition to the Pose, I had to remember where to place him.  Not
into the wall, not below the floor.

Not wanting to give up, the very first pose is when he takes his very first
stride, I used

  vtransform  and  VProject_Plane macros

to calculate where his forward heal and toes would ended up.  By placing
transparent circles I verified that my calculations were correct. Much to my
surprise, they were.

Well, from then on it takes him 4 poses, to bring his back leg into cross over
position.  Throughout all those poses, i.e frame_numbers 6..25, I tried to use

   #if ( !VZero( Forward_Heal_Coord ) )
       object{ PosedHumanoid }
       Align_Trans( PosedHumanoid, -y, Reference_Point )
       Align_Trans( PosedHumanoid,  z, Forward_Foot_Coord )
   #else
       object{ PosedHumanoid }
       Align_Trans( PosedHumanoid, -y, Reference_Point )
       Align_Trans( PosedHumanoid, -z, Reference_Point )
   #end

The first part of the if condition was meant to align him with his forward foot
always - with an assumption that his forward toes would be his right most point
(not a good assumption, I know, just to see him walking I was willing to live
with this assumption for now.

Reference_Point was a globally declared vector attempted to prevent him from
dropping below floor or moving into walls.

I was quite disappointed this last attempt did not save the day.

Given, I had not had much luck with PovPerson until now either. And I am
convinced, my simple approach will not save the day.  I do need to keep track
of location as well as rotation of joints of my skeletal tree.

After realizing that I started searching internet again.  Much to my shock I
discovered a freeware character animation software:  Blender, which provided
both build in forward and inverse kinematics.  It was rated next to 3dMax &
Maya.

Has anyone had much/any experience with it.  Am I daydreaming?

Thanks
Meltem

>
> > Well, this is the second time I am attempting to respond to this posting,
> > the
> > first one has disappeared on me.  If they both appear, please accept my
> > appologies.
> >
>
> Does that mean you can't see my response to your first attempt either?
> I find that, if stuff doesn't appear, it's helpful to look at the same
> newsgroup on http://news.povray.org as a reference, but it still doesn't
> guarantee that everyone can see the same things.

NO, No, I was able to see your response.  False alarm.  I was just being
impatient.

Thanks for all your help
Meltem

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