Oh, no ! You are also working on a clone of "Do! Run Run" !
I started mine 4 months ago... Now I must hurry up to finish it first :)
In my version, which, by the way looks almost identical to yours, all shadows are part of one surface. When I add a shadow, I add a textured quad to shadow surface and remember vertex indexes for that shadow. Then, when players/enemies move, I manually update positions of vertices that belong to that shadow. This is the fastest solution. Only problem is sloped parts of the terrain, but slopes are always on fixed angle, so that is also not very hard to do.
I started mine 4 months ago... Now I must hurry up to finish it first :)
In my version, which, by the way looks almost identical to yours, all shadows are part of one surface. When I add a shadow, I add a textured quad to shadow surface and remember vertex indexes for that shadow. Then, when players/enemies move, I manually update positions of vertices that belong to that shadow. This is the fastest solution. Only problem is sloped parts of the terrain, but slopes are always on fixed angle, so that is also not very hard to do.