So I’m aware of the problems with transparency sorting algorithms, in that per-pixel transparency is currently a somewhat unsolved problem. However, because of this, Unreal seems to have opted to force object-based transparency sorting in order to avoid the performance hit from per-pixel sorting. I understand that.
It does seem somewhat odd, though, that there is no option for vertex-based transparency sorting. While not as accurate as per-pixel sorting, sorting transparent objects per vertex is a good approximation for most use cases, and comes at a fraction of the performance cost. The method of implementing it is also not hugely different from object-based sorting, since it’s fundamentally the same, but considering individual triangles rather than entire meshes.
The fact is that object-only translucency is rather outdated, and many modern systems use the new per-pixel approaches. I understand that since Epic don’t use this internally, they aren’t willing to put the time and money into developing the feature, and from a business perspective I understand that, but could we at least get the option for vertex-based sorting? It could drastically increase the graphical fidelity of many games (particularly now that large water planes are easier to create thanks to the new forward rendering option), and shouldn’t be too expensive to implement.