{
 usage: U*UVn and V*UVn
 refl: normalized tiling 
 
 A1: U tile size 
 A2: V tile size
 A3: seam_width
 usage:
 void mixfunc floor
 4 tile seam refl uvn.cal
 0
 3 5 5 .05

}
UVn = if(and(Nx^2+Ny^2-FTINY,Nz^2-FTINY),sin(atan(sqrt(Nx^2+Ny^2)/Nz)),1);
refl = if(and(abs(frac(U*UVn/A1))-A3/A1,abs(frac(V*UVn/A2))-A3/A2),1,0);
