Due to request, I have added a simple demo of realtime shadows to the example windows executable and to the practical project source code. 

There is a little inconsistency in naming (I accidentally switch between lightmap and shadowmap a few times), but the code is commented. 

I intend to to a video/text post at some point in future explaining how this works in more detail, hopefully allowing more people to add shadows to their games in general.

The version with shadows is currently available at no extra cost.