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View Full Version : creating alpha for stained texture?

jasonhuang1115
12-21-2007, 06:32 PM
hi, CGer,

I am texturing a sort of rusty metal. Here is the base layer.

http://farm3.static.flickr.com/2008/2126670903_526f4e8a3d.jpg

Then I use burn tool to make some sort of stain. I want to have an alpha channel for the stain ONLY, because later on I am going to use a layered shader for the metal object. The base layer will be a shiny blinn and on top of it is a lambert with this masked stain texture. Here is the stain painted on the base layer.

http://farm3.static.flickr.com/2181/2127446894_be5b015f55.jpg

The stain will be a LOT more detail/complicated, so I have no idea how to quickly create a alpha channel for it. I have tried the "Alpha channel from Visible layers" inside of Video Action, and it's not working.

Any thoughts?
pgraham
12-21-2007, 07:13 PM
if you paint the stain on its own layer all you have to do is ctrl-click (cmd on mac) on the layer thumbnail to select transparency. Then create a new channel and edit->fill the selection with white.
jasonhuang1115
12-21-2007, 07:26 PM
if you paint the stain on its own layer all you have to do is ctrl-click (cmd on mac) on the layer thumbnail to select transparency. Then create a new channel and edit->fill the selection with white.


Thanks pgraham. Unfortunately, I am not painting the stain on another layer but directly using burn tool to paint the stain from the original base layer(or copied original base layer). I thought I could create new a blank layer on top of the base layer and then "burn" out some stain, but I can't. I need the color variation underneath to burn some cool stain, and the problem now is I have no good way to separate them into two layers? :banghead:
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12-21-2007, 07:26 PM
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