View Full Version : Shadow mask with Mental Ray...?

08 August 2011, 07:15 PM
Hi guys-

I can't seem to get a shadow rendered from my scene without using Software Render, as opposed to Mental Ray with Sun and sky.

I have a lovely scene with Physical sun and sky - lets say one object and the ground that it is casting the shadow upon. I would like both the final gather shadows (AO I guess) as well as the actual shadow cast by the SunDirection light to live on it's own render layer.

For some reason, applying "UseBackground" to the ground object with shadow mask on doesn't capture the shadows... though it does capture the AO or final gather cast by the object.... Help....?

my work around: I can accomplish this in Maya Software: apply Use background to both, and duplicate the sunDirection light and turn on Depth map shadows...but that sucks!

any suggestions greatly appreciated.

08 August 2011, 09:31 AM
The Use Background shader doesn't understand the Sun and Sky shaders. (Thanks Autodesk!)

It has basically been replaced by an unexposed set of shaders (Production Shaders) that have a modern version called: mip_matteshadow

Here's a good start from Zap (he wrote them): Production Shaders (Hidden Gems) (

08 August 2011, 12:59 AM
Super highly appreciate that help!

and i feel like less of a dumbass.... :)

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08 August 2011, 12:59 AM
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