Been tweaking my lens-flare again for the past few days and now reaching a point where I want to try some kind of anamorphic bloom.
Right now I went with a hack where I modify one of the downsample texture when it is fed for the upsample pass. It is giving me a rough idea of what to expect, but it's not good enough yet (not sharp enough, and some flickering issue to manage still).
Will likely need to do a proper downsample/upsample process too.