[Alpha Channel] Rendering alpha while respecting refractions from the HDRI

Support Lighting and Rendering
1

Introduction

Greetings I’ll get straight to the point!
Is it possible to render alpha layer while respecting the refractions from the HDRI?

Situation

I want to just have a good cutout of alpha of a water splash while retaining the lighting placement and the HDRI because by not having the lighting from the scene, it makes the water look very black/grey/dark.

Reference

In Redshift, there is an option called “Refraction Affects Alpha Channel” and was wondering if it is possible to replicate this in Blender.

Thanks in advance!

2

This problem seems to require an appropriate solution depending on the situation you are trying to use. :thinking:
I think the only basic support is the Film setting.

Film
https://docs.blender.org/manual/en/latest/render/cycles/render_settings/film.html

Transparent
Render the background transparent, for compositing the image over another background after rendering.

Transparent Glass
Render transmissive surfaces as transparent, for compositing glass over another background.

Roughness Threshold
For transparent glass, keep surfaces with roughness above the threshold opaque.

If it’s for synthesis, I don’t know if the video can be referenced, but I’m attaching it.

For source clips with transparency, which are usually used for image synthesis, the background color is black.

Use black and use mixed layer mode.