Weighted blended OIT (WBOIT)
An approximation of order-independent transparency that weights each fragment by depth and blends additively, so no sorting is needed.
Correct transparency requires fragments to be blended back to front, which means sorting per pixel — expensive and awkward. Morgan McGuire and Louis Bavoil proposed a shortcut in 2013 (JCGT): give each fragment a weight that falls off with depth, accumulate colour and weight in two buffers, and divide at the end. No sorting is needed and the submission order is irrelevant.
The result isn't physically exact — overlapping layers close together can look wrong — but for smoke, particles and glass it is usually good enough and extremely cheap. Unlike depth peeling, which is correct but costs one pass per layer, WBOIT is a single pass.