while changing some of my render batches design to support static and dynamic batches better and faster, i decided to add this nice fake volume effect that i called light flares or volume flares.
unlike the simple 4 vertices billboard/sprite flares that we rotate to face the camera those flares are different and look much better.
when editing the map i place quad shapes aligned with scene geometry and gives them the special flares material, inside the engine i build special border extruded by specific size (defined inside material script) and make sure they always face the viewer.
i also make sure the flare wont be visible if the camera position placed behind.
when the position of the camera is at front and smoothly become behind, i take the distance from camera position to the flare plane and use it to compute flare intensity so the flare will smoothly become invisible the more the camera become closer.
also i bind it a built-in texture which encoded a quadratic function so the borders of will have a smooth falloff effect.
there are few tiny things here and there (setting texcoords and such) but this is the main idea.
here is a screenshot to show this in action: