* - 3 attrNames for local frame (3xVEC3) : Tangent, Bitangent and Normal vector

* - N attrNames for the function coefficients (NxVEC3) : N RGB coefficients being successively the constants, the linears (v then u), the quadratics, etc. : : a0 + a1*v + a2*u + a3*u*v + a4*v^2 + a5*u^2.