这个曲面节点通过Greg Ward码实现了基于光线照明的各向异性材质。
如果U和V大致相等。高光部分会是各向同性的。如果它们不同，高光会是各向异性的。
Diff Spec U-Rough V-Rough
rolled brass .1 .33 .05 .16
rolled aluminum .1 .21 .04 .09
brushed aluminum .15 .19 .088 .13
varnished plywood .25 .025 .04 .11
enamel finished metal .25 .047 .08 .096
painted cardboard box .19 .043 .076 .085
white ceramic tile .7 .05 .071 .071
glossy grey paper .29 .083 .082 .082
ivory computer plastic .45 .043 .13 .13
plastic laminate .67 .07 .092 .092
