// localN == localV == float3(0.0, 0.0, 1.0).
NdotH = localH.z;
// Compute { L = reflect(-localV, H) }.
// Compute { L = reflect(-localV, localH) }.
float VdotH = NdotH;
L = float3(0.0, 0.0, -1.0) + 2.0 * VdotH * localH;