I have a scene with camera facing billboards drawn with depth write off so they appear on top of other objects. I would like to draw each sprite so that any obscured pixels are drawn with a very low opacity. So that obscured portions of each sprite are visible but very faint.
Could anyone point me in the direction of a solution? I am using Threejs but I imagine the solution will be shader (glsl) based. I already have the depth texture for the scene available.
Sketchfab implements this with its annotations, which is the effect I would like to acheive.