Is it possible to use ISL to colour faces depending on their normal?

If so, how ?

normalWS() returns the shading normal in world space

in other words you can blend materials depending on the shading normal relative to a world direction, not relative to the geometric normal itself.

Still that may be usefull for leaves, a field left to explore. Being able to determinate wether the shaded point is on the positive or negative side of the normal is an active request !

That worked - well sort of - I just found I needed the render to be flat shaded as well showing just the different coloured normals. Instead I ended up breaking up the mesh manually according to the normals, assigned each one a new material and then used the 'material id' render mode in Blendigo. Worked perfect and mega fast! Can't show it though unfortunately