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Aikiman
12-05-2008, 12:45 AM
Like the title suggests, how do I do a basic light pass in 2008? Basically i want the diffuse but no the objects alpha, I havnt done this for a while. ;O)

Aikiman
12-05-2008, 10:56 PM
Is this possible? Surely you can separate your light pass so that you can screen it over a plate. I tried using Mayas passes and then changing the matt opacity settings on the material but no luck and had a play with the objects render settings but I still get alpha.

redforty
12-06-2008, 01:27 AM
Basically i want the diffuse but no the objects alpha...

I'm not exactly sure what you're asking, but if you're interested in Lighting passes, I found this technique extremely helpful:

http://pigeonimpossible.com/podcast/003.html

Aikiman
12-07-2008, 08:23 AM
I'm not exactly sure what you're asking, but if you're interested in Lighting passes, I found this technique extremely helpful:

http://pigeonimpossible.com/podcast/003.html

Hi, yeah I have a little bit of know how on passes I was just a little confused as to how I can take a light pass on a ground plane and screen it over to a background plate like a still image. For example its easy to do with a shadow by using the Use Background Shader.

jeremybirn
12-08-2008, 01:26 PM
It would be possible to set-up a shader where the luminance got copied into the alpha channel, similar to how a shadow appears with use background, but I don't think it would really be useful in the comp. If you're going to Add or Screen an image over another plate, then you don't need to worry about the alpha at all. Parts of the image that are pure black will not have any effect when Added or Screened, so I'd just worry about getting the lighting you want, and assume that black areas won't change anything.

-jeremy

tristanm
12-08-2008, 05:49 PM
You can also (in composite) use the luminance as the matte...but simply Screening the isolated diffuse pass over top is best.

Aikiman
12-08-2008, 06:56 PM
Hey thanks guys :o) Yes I figured that it may be okay just to create a textureless lambert shader to gather the lighting info and screen it over a plate disregarding my alpha, looks like I was over-complicating it a little.

cheers again.

Redsand1080
12-10-2008, 02:59 PM
Is there a way to do this in 2009 by simply exporting the framebuffer that contains the light's luminence data before it's added to the material color? For example, i have the ambient color, the diffuse shading to multiply over that, and now i just need the luminence values from the light to add on to the color.


Any ideas?


Thanks!:thumbsup:

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