I would imagine that this isn’t possible and I’ll get laughed out of the building, but would it be possible to create a “choke” value for the opacity map? Something that basically expands or contracts the opacity map by a couple of pixels, perhaps even has a feather option? I know that with raster images this might not be possible, but thought I’d ask anyway.
A while back I had a fairly complex pattern for an opacity map, but it wasn’t quite cutting out enough - I ended up spending quite a bit of time in photoshop trying to increase the areas that were being cut out as they were leaving large halo’s - it’s not essential I guess, but would save time.
It’d have been much quicker to do with a comp tool, through a luma key, and an alpha dilate/erode.
Why burden the rendering with doing it procedurally?