Re: texture alpha: premultiplied or not?

[James W. W. <os...@jw...>]

On May 11, 2007, at 12:22 PM, Roger Holmes wrote:

> I have opened your model on my latest product using Quesa and on an
> old G4 running OS9 and QuickDraw3D.
>
> On the OLD machine with QuickDraw3D I see two surfaces, an opaque
> grey one and in front of it a patterned one. With the interactive
> renderer there is no transparency in either, but with the Microspot
> Renderer the white parts of the patterned surface do not appear i.e.
> they are transparent. Possibly the NuBus accelerator card and/or
> LightWorks supported transparency.

I opened the corrected model on a G4 running OS 9.2, and saw the  
image below (assuming it comes through the mail) in the interactive  
renderer.  I'm not sure what to make of it.  It's obviously not  
ignoring the alpha channel, but the white halos suggest that maybe  
it's treating texels as fully opaque unless the alpha value is  
exactly 0.