站长说的很对,补充一下: # 9t/j`{
Normal Vector *Tlv'E.M
The Normal Vector is a vector in 3D space that is used to orient the projection vKt_z@{{L
plane for the irradiance map. The plane is defined to be perpendicular to the %Fv)$ :b
Normal Vector, and the irradiance incident on the selected surface is projected E*l"uV
onto this plane. When the map is displayed, the normal vector is pointing toward 6p@ts`#
you. 88K*d8m
Up Vector g;h&Xkp
The Up Vector is a vector in 3D space that is used to orient the projection plane J\*d4I<(Rt
for the irradiance map. The plane is defined so that the Up Vector is parallel to the uprQy<I@
vertical side of the plane. The irradiance incident on the selected surface is $3ILVT
projected onto this plane. When the map is displayed, the up vector will point ;gyE5n-{
toward the top of the screen.