Semi-transparent shadows based on material

I have a window material. Some parts are non-transparent (the window bars and overlay mesh), some parts are almost fully transparent (glass), and some are semi transparent (dirt marks, smudges, grime). Is there any way to make a shadow project this? all I’m getting right now is no shadow. The material is in the transparent material mode. The thing is, none of the material is fully transparent, it’s either semi-transparent, or not at all, and I would like the shadows to show that.

Thanks.

bump
Need little shadow for glass doors.