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Francis Bievre avatar image
Francis Bievre asked ·

planet atmosphere with C4DtoA

Hello,


I am finding it really hard to produce a planet atmosphere with Arnold when it was easy with C4D engine.

I tried to use a volume shader on a sphere, following the documentation tutorial for Maya, but it produces a hard edge which does not look like the falloff that we should see on the outer end of an atmosphere seen from space.

I tried to plug a ramp into the density so that the atmosphere gets thinner on the outside but it does not work.

SO now I am following this HtoA tutorial that does not use volume at all ans seems to produce good results.

https://docs.arnoldrenderer.com/display/A5ARNTUT/How+to+Render+a+Planet+Atmosphere


But I can't follow this instruction : create a FacingRatio and a Range shader. Connect the FacingRatio float to Range input and the Range rgb to Standard Surface transmission_depth.


Because it looks like you can't plug anything into depth in C4DtoA.

Or maybe does it translate another way in C4DtoA ?


Thanks for your help !


Francis


shader
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Lee Griggs avatar image
Lee Griggs answered ·

JFYI, there is this tutorial too.

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Thank you Lee, I tried it but unfortunately there is no falloff on the outer edge of the atmosphere which makes it look quite fake

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Francis Bievre avatar image
Francis Bievre answered ·

Thank you Peter ! It works now !

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Peter Horvath avatar image
Peter Horvath answered ·

That seems to be a bug, Transmission Depth should be linkable. I'll fix this in the next release. Meanwhile you should be able to fix it locally by editing the plugins/C4DtoA/c4dtoa.mtd file. Look for this:

 [attr transmission_depth]
     min                FLOAT   0.0
     softmax            FLOAT   10.0 
     c4d.step           FLOAT   0.1
     c4d.gui_type       INT     10
     linkable           BOOL    false

and remove the line with the linkable flag.

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Hello Peter,


Will it work if I send my scene with a shader using this bugfix to a farm ?

Or their Arnold is not going to be able to read my setup ?


Thanks !


Francis

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It's not gonna work until the fix is released and the farm is updated to the new version.

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