Re: Alpha Blending?


> Thanks for the reply, Bill.  I see what you are saying regarding
> ScalarMap vs. ConstantMap transparency.  However, perhaps I'm not so
> concerned with *varying* opacity.  The colored wedges that are in the
> example are Irregular2DSets (not a Field) and are only used to
> distinguish between one "wedge" (beamwidth) and the next.  I would like
> to illustrate the overlap between these wedges and hoped that by placing
> one on top of the other, the opacity (or colors) of the overlaping areas
> would be different than the individual wedge.
> . . .

You could try to make the geometry of each beam a little
wider so they overlap. That might give you the effect you

> On a different topic, I am trying to use the addReferences(DataRenderer,
> DataReference[], ConstantMap[][]) method of the DisplayImpl class and
> have not been successful.
> Here is a snippet of my code:
> . . .
>      allBeamsRef = new DataReferenceImpl[NUM_ANGLES];
> . . .
>        allBeamsRef[i] = new DataReferenceImpl("allBeamsRef" + i);
> . . .
>      rhiDisplay.addReferences(allBeamsRend, allBeamsRef);
> . . .
> I get the following runtime error:
> Exception in thread "main" visad.DisplayException:
> DefaultRendererJ3D.setLinks: must be exactly one DataDisplayLink
> and the line number is associated with:
> rhiDisplay.addReferences(allBeamsRend, allBeamsRef);

For DefaultRendererJ3D, the array of DataReferences must
consist of exactly one DataReference. For what you want
to do, you must put the call to addReferences() inside
the loop, and pass only one DataReference at a time
(in a single length array if you like). The signature
allows multiple DataReferences for those custom
DataRenderers that can handle them.

Good luck,