[Bf-funboard] Using ONLY an Image's Alpha Channel

Douglas Bischoff bischofftep at mac.com
Sun Jan 15 17:58:23 CET 2006

Hello, all!

Looking for a shortcut to a two-step process.

I'm familiar with how to use an image's alpha channel to make the  
background color show through: this request has nothing to do with  
modifying IMAGE alpha.

What I'm trying to do is use the Alpha channel of an RGBA image to  
affect the Alpha value of the texture (ZAlpha or RayAlpha, doesn't  

Right now it seems the only way to do this is to save the Alpha  
channel of the image as its own 8-bit grayscale file and apply THAT  
as a second Texture channel. A faster way would be for the Image pane  
of the Texture panel to have a new button called "OnlyAlpha" that  
ignores the RGB channels of the image and loads the image's Alpha  
Channel ONLY.

This would allow you to use the image to modify "Col" in one texture  
channel, then load the same image file and select "Only Alpha" and  
use THAT to modify "Alpha" so that the Col completely "cookie  
cutter's" out the faces its applied to.

Anyone want to tackle this seemingly simple idea?

"Bischofftep" aka

Doug Bischoff
Ceridwen Productions

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