stanland wrote: Mon Nov 19, 2018 12:48 pm
2) Why Bidir engine only supports a few AOVs and will it support in the future all render passes?
BiDir uses both eye paths and light paths at the same time. So, while Path uses a single image buffer, BiDir uses 2 with different buffers and normalization strategies (one for eye path samples and one for light path samples).
Given the BiDir Vs. Path core differences, there are few reasons to explain why we support very few AOVs in BiDir:
1) Some AOV doesn't make very much sense in BiDir context given it works in both directions.
2) Even if a AOV makes sense in BiDir context, it would require 2 buffers instead of 1 (i.e. requires a more RAM). And they are more complex to handle.
3) BiDir is (often) used for photo-realism where AOVs are (often) not used. You set up a scene like in a real studio and fire-and-forget the rendering without any particular AOV composition at the end.
4) I'm lazy
It doesn't mean BiDir can not have support for far more AOVs but it is a task with a quite low priority at the moment.