CGTalk - useBackground and mask

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KungKrille

10-12-2009, 12:42 PM

I have a particle field with planes that has transparent textures applied to them. There are objects inside the field that are partly covered by the planes. I need to render a sequence where the objects only are visible for compositing later. I have assigned useBackground shaders to the planes and connected the textures alpha to Matte Opacity. It doesn´t seem to work though because Mentalray ignores the textures alpha and I get black rectangles instead. What is the proper way of doing this?

Edit:
I added a link to a picture. Zone A: The object is partly covered by planes that are rendered as rectangles. The alpha in the texture is ignored. Zone B: This object is covered by real geometry and is masked correctly. That is the result I want for zone A as well

Image (http://www.reclaimthedata.com/cellmembrane/mask.jpg)

thehive

10-12-2009, 07:45 PM

you could make color ids for the planes an particels an extract them out later in shake or nuke. hope that helps

KungKrille

10-13-2009, 08:09 AM

I don´t understand what you are talking about :) I just want to know how to connect the alpha from a texture to a useBackground shader - if it´s possible at all

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10-13-2009, 08:09 AM

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