k3d/share/shaders/k3d_fur2.sl:75:    varying normal nSN = normalize( surface_normal );
k3d/share/shaders/k3d_fur2.sl:76:    vector S = nSN^T;     /* Cross product of the tangent along the hair and surface normal */
k3d/share/shaders/k3d_fur2.sl:79:    float  l = clamp(nSN.T,0,1);  /* Dot of surface_normal and T, used for blending */
k3d/share/shaders/k3d_fur2.sl:98:    norm_hair = (l * nSN) + ( (1-l) * N_hair);
