I know how to add image planes onto a Montra render that grabs the export from shaders applied to the various geometry in the scene. Is there a way to have different shaders for the same object going into the same OpenEXR file?

For example, if I have a shadow pass and an ambient occlusion pass as two separate takes, can I have those to takes render out as two separate channels to an OpenEXR at render time?

Inside my main shader I just add what I would term my arbitrary shaders.Like id and occlusion. I stick them in different “ if blocks ” that use a toggle param. Then in my image planes I just toggle on my occlusion if I want it calculated . Plus I add the export param name for my occlusion !.
If your still stuck I have a basic scene showing this which I will be able to post up at the weekend as I am busy finishing off a show.

r

I understand the basis behind how that would work, I think it would help if I saw the implementation. I would love to see that file as an example, so I can see the way you set it up. Thanks for the help and I hope the show went well.

RJQ

see attached done in H10 with sticky notes

r

Thank you so much. I went through it a few times and it seems to make sense. I had never made my own shader in Houdini (I used to make procedural shaders in Maya all the time), but it seems to be a bit easier than I thought.

Best,
RJQ

No probs

post up any examples you make

r

Looking into it more, I notice that the shadow matte shader needs to be plugged into its own Output Variables and Parameters node within the Vex Surface SHOP. Does that mean that you can't do the same thing with a shadow as done with the Object ID and Ambient Occlusion because it the color, transparency, and face forward all need to be output from the VEX Builder as one group?

Of course you can do it ! or you can use this technique I posted here

http://forums.odforce.net/index.php?showtopic=8775 [forums.odforce.net]

r

I see what you did with the Switcher Node, but I am not sure how the $RENDERPASS is passed on (no pun intended) to the Image Plane parameter in a ROP so I can get the shadow pass along with the other Image Planes in a single EXR.

I basically don't know what to type in for the VEX variable in the Mantra node. Thank you for being so helpful with this.

The technique shown , lets you switch to a different shader . Its called by the Mantra ROP. If you wanted a shadow shader pass in your exr , just build it as shown with my occlusion shader. Just give it an export value.

get me on AIM if you want ……..

rob

hmm, let's say you have a scene with a light that has shadows enabled in it. if you render this image the shadows are added to the beauty-pass (of course..).
so the shadow data has to be somewhere and it was definitely used to generate the beauty-pass.

and now my question: is there definitely no pre-built variable to extract the shadow pass to its own image plane during render time?

i think the 2 mentioned solutions are interesting, but .. well, it could be easier, couldn't it? maybe i'm totally wrong, but i had to ask this.


thx in advance. :>

There is a way to render out a shadow pass as a separate take, but that would put it as another channel along with all of the other image planes in a single Open EXR file. The advice that Circus Monkey gave worked, and I also found a way by reconstructing the shadow shader within whatever shader I was using and adding that export parameter to an image plane in my Mantra node.

hmm, could you post a material with this shadow stuff added please? it looks like i fail with this task.

or anyone else maybe?

Do you have scene where you have attempted this ?

could be any scene .. it's about the shader to get some sort of shadow output.
and .. no, i didnt save any shader_creation_attempts either because they never worked out.