First off, very new to blender development. Only started cause i really wanna implement this feature 
I’ve managed to built blender tho.
In short what i want to do is add another output to the hair info node. So you for a strand can get the normal of the surface the strand is emmited from, instead of the strands actual normals. This would help achieve some very interesting cel-shading possibilities for hair!
(this is conceptual)
It would essentially be like using the data tranfer modifier from one mesh to another, to transfer the normals. Though that’s not possible with hair particles, unless you convert them all into separate meshes, would anyone know if something like this is doable, and if so how to tackle it best?