I am doing a theatre scene, which is mainly lit with fresnel lanterns (https://en.wikipedia.org/wiki/Fresnel_lantern). The lamps themselves are not visible, but their light cone is.
Unfortunately, I can not get this to look right with blender. First of all, spots seem to be incapable of other forms than round, but due to the use of barn doors (https://en.wikipedia.org/wiki/Stage_lighting_accessories#Barn_doors), theatrical lighting equipment gives more of a rectangular shape. I fixed this with placing my spot inside a cube which is open on one side, however, this gives me rectangular cones with sharp borders, rather than soft borders as real fresnel lamps do.
Any hints on how to get a rectangular cone with soft borders? Ideally, it would not be too hard to change angle and size of the cone, as I may need several attempts to point them correctly.
I would prefer a solution that works with Eevee, but I can switch back to Cycles if this makes things easier.