"Chris B" <nom### [at] nomailcom> wrote:

Thank you very much for responding so promptly.

I have a better idea of POV_RAY SDL environment .

I hope you will have time to respond to my other post.

Thanks again,
Meltem

> "melo" <mel### [at] coxnet> wrote in message
> news:web.47a6d01895eefef63c0d56f20@news.povray.org...
> > Well I have a hierarchically structured CSG tree. Different parts of the
> > tree at
> > different levels represent different body parts.
> >
> > #declare Humanoid =
> >  union { // trunk
> >    cone{ ..}
> >    sphere{ ...}
> >    union{  // right arm
> >      sphere{..} // shoulder
> >      cone{..}   // upperarm
> >      union{ // lower right arm
> >        sphere{..} // elbow
> >        cone{..} // lowerarm
> >        union{
> >           sphere{..} wrist
> >           object{ right_hand }
> >           }
> >        }
> >    }
> >
> > This structuring allows me to animate by rotating about joints/spheres.
> > After
> > rotating a number of body parts, the coordinates of the sphere, cone
> > objects
> > that make up Humanoid object change.
> >
> > Now questions:
> > 1. Do those changes get reflected back in the POV-RAY SDL variable
> > Humanoid?
>
> Once the parser has read the definition in your SDL the internal
> representation of the variable Humanoid will end up holding an internal
> representation of the shapes resulting from the application of the
> transformations to the objects. You won't be able to access that internal
> representation from further down in your SDL other than by referencing the
> variable 'Humanoid'. That is to say that POV-Ray doesn't expose the internal
> representation.
>
> It's different from the way things like HTML and VRML have evolved with
> their separation between the DOM and scripting to support interrogation of
> the current DOM hierarchy from the scripting language.
>
> > 2. Is it possible to traverse my CSG Unioned tree object and figure out
> > where
> > the limbs of my virtual guy have ended up at? [I need to be able to do
> > this so
> > I can put my Humanoid into the pose he was at the end of the prev stage,
> > at the
> > beginning of the new stage.)
>
> No. You won't be able to traverse the elements of the composite CSG object
> as you've currently got it defined. The only access you subsequently have to
> it is through the variable 'Humanoid'. There are some functions that give
> you specific pieces of information about it, such as the min_extents() and
> max_extents() vector functions, but the information returned is for the
> whole object, not for individual components.
>
> The simplest solution is likely to be to store away the information you will
> need later as you go through building up your object definition. You will
> find arrays handy for this as they can store all sorts of things, including
> vectors for positions and rotations, but also entire transformations.
> Transformations assigned to an identifier can subsequently be applied to
> position vectors using the 'vtransform' macro.
>
> Regards,
> Chris B.

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