“Ground Glass” and solving for the “X” in the BSDF. を略してGGXらしい…。

According to Steve, he and friend were originally researching "Ground Glass" and solving for the "X" in the BSDF.

— Morgan (@CasualEffects) 2016年10月3日

GGXという単語が初出であるWalterの論文に曇りガラスが出ているので，なんとなく納得。