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vfx
08-09-2009, 04:16 PM
I am trying to break my scene up into layers for comp.. I am using the useBackground shader as a mask for an object, however this then turns that object into a solid black object, and thus when I render, the other objects no longer reflect the diffuse or the ambient that was originally on the object prior to masking.

Is there a solution to this?

djx
08-09-2009, 11:33 PM
Rather than useBackground as a mask, leave the original shaders and turn off primaryVisibility for those objects in the render stats part of the attribute editor. Or use the attribute spread sheet if you have many objects that need changing.

-- David

AlexTNT
08-10-2009, 11:28 AM
didn't read as it should ,i understand other thing

vfx
08-11-2009, 12:49 AM
Rather than useBackground as a mask, leave the original shaders and turn off primaryVisibility for those objects in the render stats part of the attribute editor. Or use the attribute spread sheet if you have many objects that need changing.

-- David

Maybe I'm not explaining myself well enough.. if I turn off primary visibility, then the object no longer works to matte out the part of the object which is behind it.

Here's an example to help better explain:

1. Snake crawls over branch.
2. Render just snake layer.. so branch layer needs to be invisible but provide colour detail for the FG on the snake, and it needs to contribute to the alpha masking out the section of the snake which is behind the branch.

I have considered just rendering out the whole snake and then doing a matte render pass (black and white) and just doing the mask work in post, but it's less render expensive to render only what the camera sees of the snake.

3d165p05
08-15-2009, 12:47 AM
did you find the solution? If you did, please share.
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what render are you using? I had some trouble using useBackground shader in conjunction with MR.
Possible solution is using mip_matteshadow (from Production Shader Library), but I still don't know how to use it (hoping tomorrow I'll know :rolleyes: )

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