Jeff Lee wrote :
> 
> I've been trying to use the +UA (output Alpha-channel data) option to
> create sprites with transparency information.  Normally, it works like a
> charm.
> 
> But if I want to render, say, a glass sphere with something opaque
> inside it, the opaque bit still turns out transparent.  It looks as
> though POV-Ray just takes the transparency data of the first surface it
> strikes, and though it continues to calculate the RGB values by
> splitting the rays, etc., it doesn't seem to update the transparency
> component any further.
> 
> Is there a way around this?
> 

You're right: I have the same problem in a scene with a planet (sphere)
surrounded by a semi-transparent ring.

Here's my solution: I create another scene with the same camera and objects. You
remove the light_source.
And: the background is black, the opaque objects are white, and transparent
objects vary from rgbt<1,1,1,0> (transmit=0 in the original scene) to
rgbt<1,1,1,1> (transmit=1 in the original scene).
Of course, don't forget to set finish { ambient 1 diffuse 0 }.

POV-Ray will directly render a 256-gray picture: the alpha channel you need.

It works, but it needs more work than automatic alpha-channel rendering.

___________________________________________________



To answer me, remove the Z from my adress.

Post a reply to this message