Re: Workaround for this bug?

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

On Jan 21, 2005, at 12:10 AM, Keith Wiley wrote:

> I am trying to use an alpha channel to make a soft sun that fades into 
> the background sky.  It works perfectly except at the horizon, where 
> the square shape of the plane the sun texture is put on shows up as a 
> translucent square.  This problem vanishes if I turn off fog.  I am 
> aware of the discussions pointing out that fog does not work properly 
> with alpha channeled textures...and I assume you will agree that this 
> bug is the problem I am experiencing.  My question is, does anyone 
> havea reccomendation for how to work around it?

Why not use a disk instead of a square for the sun?

> Incidently, if I make the texture "transparent" instead of alphaed it 
> works just fine, the square background is invisible.  The transparent 
> texture is made by toggling transparency instead of alpha in Meshwork. 
>  This confuses me because I assumed up until now that there is no such 
> thing as "transparency" in Quesa, and that what Meshwork is really 
> doing is simply constructing an alpha channel that is only black and 
> white and applying that to the texture in question...but since 
> Meshwork-made transparent textures work properly with fog and alpha 
> channel textures do not, I am not wondering if transparency is 
> actually something other than 1-bit alpha.

In the Geom Test example, choose the cone model.  You'll see 
transparency that is done with transparency color rather than alpha 
textures.  If you then select Toggle Texture, you will see how an 
opaque texture combines with transparency color.
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