Hi everyone

I have an expression in my ROP output path. The expression looks like this

footageOutput(“test”)

and returns something like this

/Volumes/Vault/Local_Users/rcortes/Desktop/test/test.$F4.exr

The problem im having is that when I render any frame, the expression always resolves to


/Volumes/Vault/Local_Users/rcortes/Desktop/test/test.0001.exr

However if i delete the channel so that the expresion output becomes the output path, it works just fine.
I think that for some reason, the expression is being evaluated at frame 1 and the result is being cached and used for all other frames.

Does anyone know how I can get this to work? Is there a flag to force an expression to evaluate on every frame? (I thought expressions did this by default).


Much obliged.
rcortes

Hey, Rudy

Have you tried putting the expression on the “pre-frame script” field and relative reference it in the output?
Might force the script to re-evaluate every frame…

Cheers

rafaels
Hey, Rudy

Have you tried putting the expression on the “pre-frame script” field and relative reference it in the output?
Might force the script to re-evaluate every frame…

Cheers

I thought about doing that, but I would really like to know the reason why the expression is not evaluated every frame and if there is a way to do so.

Cheers

I found a solution

I wrapped the output path with a hou.expandString() right before I return from the function.

Cheers
Rudy