Re: transparency & specularity

[Frank C <li...@si...>]

On 5-Apr-04, at 12:53 AM, James W. Walker wrote:

> On Mar 28, 2004, at 1:11 AM, Frank C wrote:
>
>> It could be that the specular highlights you see in old builds may be  
>> an errant state left over from some solid geometry, rather than  
>> specular settings specific to the transparent geometry.
>
> I think you're right.  Apparently Quesa doesn't really have any  
> provision for specular highlights on transparent material.  I found a  
> hint about how to do it:  
> <http://www.opengl.org/resources/faq/technical/ 
> transparency.htm#blen0030>
>
> I now have some code that renders shiny transparent stuff fairly  
> nicely, but I wonder whether it should be an option, since there is a  
> cost.  In a quick test in Geom Test, the frame rate went from about  
> 355 FPS down to 325 FPS when I added the extra shininess processing.   
> I could make it a renderer option, like the depth of the depth buffer.  
>  Opinions, anyone?

Is a global switch really necessary? Quesa/QD3D already allows you to  
control Phong shading per-group, so it's already possible to turn off  
specularity on a per-object basis (regardless if they're transparent or  
not). You could also use the specular colour as a hint, and turn off  
the extra processing when it's pure black, since the end result would  
be the same.

Frank.