Texture splatting and Normal mapping

Hello!

So i am currently using a splatmap which is constructed in the geometry shader based on the height. This, however is very simplistic and doesnt look realistic so i am transitioning to a splatmap texture with each texture weight encoded in the RGBA channels (sand, grass, etc). This is blended in the fragment(pixel) shader with the diffuse textures according to the read weight at the current texture point.

My issue is with the normal mapping.

So from the heightmap, it is possible to generate a normal map (using GIMP normalmap for example) and this is being read and …