shadow pass for maya fluids?

#1

I know that one can use the use background shader to create a shadow pass for use in a compositing package, but what about fluids? I tried the same approach, and it didn’t work.

Any known workarounds or hacks to get something usable?

Thanks alot

#2

What I usually do…Apply a “useBackground” shader on the geometry you would like your fluids to cast shadows on. Select your fluids and under your “Render Stats” in the attribute editor. Just turn off everything and leave “Cast Shadow” checked. Test Render. Notice if you select your alpha channel you will see the alpha of the shadows casted by the fluids. Bring this pass into your composition, and you should have isolated shadows for your fluids. Hope this helps.

#3

maybe I’m doing something else wrong? What you outlined is basically what I did, I made a new scene, created a directional, turned on ray traced shadows, switched the render to mental ray, applied a use background shader to a plane under the fluids, and hit render. nothing!
ahh

#4

Do you have auto-volume on and segment shadows on in the render settings?

#5

Using raytracing shadows with MentalRay…Wolfgang is correct. If “Segments” are not enabled under the Shadows parameter in your globals…you wont get an alpha for your shadows. You should be good to go now.

#6

you are all genius’s.

Thank you, segmented shadows worked perfectly. I could not find auto volume, but it didn’t seem to need it in the test scene I just tried. What does it do?

#7

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.