Re: VisAD and transparency

Hi JR,

Iso-surface triangles (and triangles from other sources)
in VisAD get sewn together in long polytrianlge strips
which greatly increase efficiency, and these strips are
in general not compatable with sorting. As I recall, Java3D
does provide a way to segregate triangles into multiple
Geometries that it will then sort in depth order, but for
this to work with complex shapes like iso-surfaces you'd
have to segregate into a very large number of Geometries.

It is possible that you may find a way to do what you want,
but it will be a lot of work and probably result in slower
rendering and greater memory use.

Good luck,
Bill

> Bill mentioned sorting the transparent polygons as a possible solution.  If
> the (isosurface) polygon data structure is accessible from VisAD, would
> implementing a simple z-sort of this list be possible?  I am not so
> concerned of a 'real-time' z-sort as the user rotates the molecule; a simple
> z-sort at the end of rotation would be sufficient to ensure that they have a
> nice looking picture after they get things into the desired orientation.
> Would this be a reasonable approach, or a futile waste of time?
>
> If this works out, I would be happy to contribute the resulting code.