#declare TileNorm = function(x,z) { max( abs(x-int(x))+abs(z-int(z))*5,1 ) }
#declare planetexture2=texture{
pigment{color White}
finish{phong .7 phong_size 1 ambient .25 reflection 0.1}
normal{ function {TileNorm(x,z) }, .15}
}
This gives an interesting surface normal... not at all what I expected.
