CGTalk - Alpha Channels

tomb

01-06-2002, 06:44 PM

I'm sure this question has a simple answer but I havn't been able to find it yet.

In Maya I want a shader with a tif being used for the colour attribute and the alpha channel of the same file being connected to the transparency attribute.

Also how do you deal with the matte colour. EG if you have red smoke on a white background and you apply the transparency map the smoke will come out pinkish. In this instance how can you define white as the matte.

Jhonus

01-06-2002, 07:31 PM

make sure you have an alpha channel setup in photoshop, and when you save the tif you need to check the box for saving alpha info (photoshop 6, dunno about the others).

In Maya you should be able to use "out transparency" or "alpha out"... (can't remember which works, but there is a difference), connect it to the respective channel on the shader.

Just fiddle around with it in a clean sanitary manner.

Hope this helps, but i only stated the obvious i think. I have no idea about the matte colour... maybe somethign to do with changing the default, or background colour of the shader (its under the shader attributes somewhere)

SheepFactory

01-09-2002, 08:19 PM

you might have to use the reverse node when connecting the outalpha to transparency if you connect the alpha and it still doesnt render right

jfrancis

01-03-2005, 07:31 PM

I put together a tutorial (http://www.digitalartform.com/archives/2004/12/transparency_ma.html) that you may find helpful.

http://www.digitalartform.com/archives/images/spriteShader1.jpg
This way is often a recipe for matte lines

http://www.digitalartform.com/archives/images/spriteShader2b.jpg
This way can come in handy under many circumstances

http://www.digitalartform.com/archives/2004/12/transparency_ma.html

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