站长说的很对,补充一下: Lc}hjK
Normal Vector ,D`jlY-1l
The Normal Vector is a vector in 3D space that is used to orient the projection MYara;k
plane for the irradiance map. The plane is defined to be perpendicular to the y,&[OrCm^\
Normal Vector, and the irradiance incident on the selected surface is projected lc5(^~
onto this plane. When the map is displayed, the normal vector is pointing toward w]T_%mdk
you. jA:'P~`Hj
Up Vector jsgDJ}
The Up Vector is a vector in 3D space that is used to orient the projection plane _7:Bxx4B
for the irradiance map. The plane is defined so that the Up Vector is parallel to the (_}q>3
vertical side of the plane. The irradiance incident on the selected surface is DpmAB.
projected onto this plane. When the map is displayed, the up vector will point )3e_Hs+
toward the top of the screen.