"kike" <dry### [at] hotmailcom> wrote in message 
news:web.48183bc4aed456fcbe7bfb550@news.povray.org...
>
> I'm nearly sure the answer to this question is a big NO but anyway:
>
> Is it possible to have an object which is transparent for the whole scene 
> but
> opaque for another single object. The idea is to reach the effect (in an
> animation) of objects dissappearing behind apparently non-existing 
> objects.
>

Hi,

You could fairly simply achieve something pretty similar if you can define 
the shape of your 'transparent' object as a prism with the outline of the 
shape as it would appear from the camera position.

Here's my thinking:
1. Define a prism object with a conic_sweep that starts back beyond the 
object you wish to dissappear and that converges to a single point at the 
camera position.
2. This object won't appear in the scene, but you can use it in a CSG 
operation to cut away the part of the dissappearing object that would be 
'concealed' by the 'transparent' object.

Clearly shadows and mirrored reflections could interfere with this effect, 
but the complexity of dealing with/faking those depends on the details of 
the scene/animation you're trying to build.

Regards,
Chris B.

Post a reply to this message