站长说的很对,补充一下: ,zc(t<|-y
Normal Vector V]^$S"Tv
The Normal Vector is a vector in 3D space that is used to orient the projection 2an f$^[
plane for the irradiance map. The plane is defined to be perpendicular to the khd4ue$
Normal Vector, and the irradiance incident on the selected surface is projected xSu >
onto this plane. When the map is displayed, the normal vector is pointing toward F'Z,]b'st3
you. d;>QhoiL
Up Vector 4p wH>1
The Up Vector is a vector in 3D space that is used to orient the projection plane p
ll)Y
for the irradiance map. The plane is defined so that the Up Vector is parallel to the $cgcX
vertical side of the plane. The irradiance incident on the selected surface is "N#Y gSr
projected onto this plane. When the map is displayed, the up vector will point 9YGY,sx
toward the top of the screen.