@Painkiller :
Thanks , in fact i tried your version , the only thing is that the include was not in the good file
It compiles and launch , bu i don't see the normal effect, even dynamic light only affects don't show any normal map effect.

I have an old example where i succeeded with normal map, i'll have to try to find it , it is hidden somewhere in some folder ?
I really need this normal map/specular working with 3DGS also.
I hope 3DGS to really quickly improve the workflow for shaders, it should be priority 1 for any one to use models with normal maps ,specular, glow, reflective , at least these very basic ones quickly from a menu instead of coding !
(Add the header for shaders and add material code)