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View Full Version : Help with Render Layers - physical sky/FG and Fluids


aghawa
11-10-2009, 09:19 AM
Hi there, i have a scene lit by a physical sky in MR with Final Gather, and i have also some Fluids in here. Of course they're IMPOSSIBLE to render with FG, really slow. So i set up a new RenderLayer including only the Fluids, and did a couple of overrides (FG off, antialiasing sampling very low). But my problem is, how can i render the shadows cast/received by/from the fluids? I assume i should include the geometry also in the fluids layer, and assigning them a shader that only serves for matte/shadowing, but i don't know how to set it up.
Any help?
Thanks :D

longrayjohnson
11-10-2009, 11:14 AM
i would do two renderlayers. one with the geometry and a blackhole shader assigned to server as holdout matte. the other one with the geometry and a usebackgroundshader to catch shadows. hope that helps

aghawa
11-10-2009, 01:57 PM
i would do two renderlayers. one with the geometry and a blackhole shader assigned to server as holdout matte. the other one with the geometry and a usebackgroundshader to catch shadows. hope that helps

Thanks longrayjohnson, that is a good idea. But i still have some questions for you :D
First: i created my first matte pass, with the geometry with a surfaceshader (black), and it serves the purpose, the fluid also get the shadows from the geometry. But i also have some particle systems, and a couple of particle instancers. I suppose i should create some black cloud shader for the particle matte, connected with the opacity of the particles, right?
Then, if i add my instancers to the layer, they are added, but nothing is shown. I see the simple particles but NOT the instances. Any clue on this?

Second question: the physicalsky adds a "sky" background. Is it good for use with the "BackgroundShader" for compositing purposes? And, using two renderlayers, i also should render the fluid two times? Because if i don't insert them in one of the layers, they will not receive in one case, or send in the second, the shadows. Right?

Thanks again man :D

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