ray casting with surface geometry

[Dimitris Agrafiotis]

Hi Lisa

Thanks for the advice especially for the bit about texture mapping two 
volumes. 

Something else now that I would like to ask.

What if I  ray cast (not with texture mapping) two overlapping volumes
but with the Erase parameter of the render window OFF. Is that the same
with taking the pixel values (RGBA) resulting from the ray casting of 
one of the volumes and putting them as initial values for the ray 
casting of the next volume?

Thanks again.
Regards 
Dimitris




On Mon, 17 Apr 2000 23:16:01 -0400 Lisa Sobierajski Avila 
<lisa.avila at kitware.com> wrote:

> Hello Dimitris,
> 
> If you ray cast a volume with opaque surface geometry in the scene, the 
> geometry is taken into consideration. At the end of geometric rendering, 
> the color/depth buffer is captured and used to bound the end points of the 
> rays that are cast. There is no need to use a ray bounder - this is only 
> necessary if you want to clip the rays against some "invisible" geometry 
> (with some limitations in shape) - for example to have a "sphere of interest".
> 
> Some things to watch out for: you cannot intermix translucent geometry with 
> volumes, you cannot have two volumes that overlap, you have to turn 
> back-to-front sorting on in the culler if you want more than one texture 
> mapped volume.
> 
> Lisa
> 
> 

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