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Render Path + AOV Path Expression

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I need some help to understand how to use some string expressions, I'm using Redshift ROP and I want to change the render paths on some AOVs using the Custom File Prefix from each AOV. I want they will be saved on the same folder like the main output path but with other names. So, I'm using this string for the main render path:

RS ROP output file name prefix: $HIP/render/$HIPNAME/$HIPNAME.$AOV.$F3.exr

And I was trying to use this expression for AOV custom path:


Because I saw in this link that this expression should return the directory from the entire string without the file name and extension but I'm not getting the file directory using this expression like this. In conclusion, I'm looking to set the render path only one time and the AOVs with custom path can load it and use other names or formats.

Thanks a lot!




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Hello, first of all, I don't understand why you don't use directly $HIP/render/$HIPNAME/$HIPNAME/BumpNormal.$F3.exr ?

Then, if you want to use the same name without the extension, like /mypathrender/myrendername_BumpNormal.$F3.exr

you can remove a number of chars with this :

`substr(chs("RS_outputFileNamePrefix"), 0, strlen(chs("RS_outputFileNamePrefix"))-4)`

Here the -4 remove the extension and the dot, if you want remove also the $F3 and the dot, then -8 must be used.


substr() > https://www.sidefx.com/docs/houdini/expressions/substr.html

Edited by fsimerey

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Hi fsimerey,


Hello, first of all, I don't understand why you don't use directly $HIP/render/$HIPNAME/$HIPNAME/BumpNormal.$F3.exr ?

Because I'm too lazy to change the name from each AOV multiple times :D, because of that I look for a more quicker solution defining the path only one time.

Thanks a lot for the substr() example, I'll try with that.



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Hey cybor09!!

Did you figure out a way to do this easily?? Please let me know.

Hoping to find a efficient way.


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Posted (edited)

Hey guys, maybe this will help?

I make use of the context editor and create variables for the main paths, then I can use that variable to define the filename in the ROP:
1) Open the context options
2) Create a new 'text' option
3) Give it a name and set the path
4) Use the variable in your path : NOTE this is the syntax backtick|@|variable name|backtick - `@variable`
5) Middle click on the field label to see the expanded path

Hope that makes sense!






Edited by Matt_K
Updated text to be clearer
  • Like 1

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Hello guys!

@fxartist420 I'm using a "temporary" solution since some months. I have a template scene with some objects, materials and RS Rops + AOVs. And on the Out context have one null that defines the render paths for different things:


And copy the paths as relative reference on the RS Rop and AOVs:




On that moment still had problems manipulating the string, this method have only one bad thing in case you use Deadline as render manager. You can't send to render directly with the .hip file because deadline got some errors with the variables:


The solution to use it with Deadline is export the RS Proxy scene files to send it to render. You can do that automatically and create presets with the Deadline node in the Out context. I attached one reduced file with this example.

I like also the feature that @Matt_K shared, maybe in some point will take a look in to this again to create a better optimized way.



RS ROP Preset example.hiplc

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Hi there,

Just in case this old topic could still help someone:

The Redshift documentation states: "The Redshift ROP has an additional variable “$AOV” that can be used to set the AOV suffix name in the output image file name. If this variable is not found, the plugin appends the AOV suffix to the end of the file name, just before the file type extension."

So to get your AOVs sequences with numbers after their name, you have to set the AOV formatting in the Common file prefix field (ie main render output) instead of the AOV custom file prefix field. The default behavior was intended for multilayer files.

So using $JOB/renders/filename.$AOV.$F4.png would save both filename.1000.png as the main render and filename.puzzleMatte.1000.png for a puzzleMatte for example.



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