When i texture paint in 2.8 how do i add shadows to see what im painting When  i texture paint I like to paint on the actual object instead of the uv map but it seems that when I set up an object ready to paint its all one colour, no distinguishable features so i don't know what im painting. 
Thanks , J.H.B.W.
When in Texture Paint mode and Rendered View go to Overlays on the top right.

At the bottom of the drop-down window for Overlays there will be a section Texture Paint and below it will say Opacity. If this is set to zero you will have full shadows on your model.

I find this makes it easier to paint directly onto the model and see where your paint is going.