fixed bug in G1 surfaces that I introduced recently
fixed bug in G1 surfaces that I introduced recently

YetAnotherMinion/core,YetAnotherMinion/core,yangf4/core,yangf4/core,yangf4/core,yangf4/core,YetAnotherMinion/core,YetAnotherMinion/core,yangf4/core,YetAnotherMinion/core