I think it would be really cool to have a shadow mask that can be placed between the sun and the model:
o Mask shape selection : Forest, Grass, Traffic, Buildings, Crowd, Zombies, Rainbow, Disco lights, UFOs, (clouds, birds, planes, leaves, rain…)
o Shadow height : Distance up from horizon the mask will start - below this will be solid.
o Slider for strength : How dark the thrown shadows are and how sharp the edges are
o Slider for fade : Solid towards horizon -> transparent towards the sky. Perhaps a 2 way fade so that sky effects could fade towards the horizon.
o Slider for saturation : Stained glass and disco ball effects with full saturation, vague grey shadows with no saturation
o Slider for animation speed : perhaps a gif animation? people walking by a window, leaves moving in the wind, flock of birds flying past, etc.
The idea is that if you looked, you wouldn't see anything actually blocking the sun; just the 'shadow' being cast.