站长说的很对,补充一下: $ibuWb"a
Normal Vector mQY_`&Jq
The Normal Vector is a vector in 3D space that is used to orient the projection $jg*pmR-
plane for the irradiance map. The plane is defined to be perpendicular to the 'D@-
Normal Vector, and the irradiance incident on the selected surface is projected FXs*vg`
onto this plane. When the map is displayed, the normal vector is pointing toward SCz(5[MZJ
you. ca>Z7qT!
Up Vector &\Amn?Iq
The Up Vector is a vector in 3D space that is used to orient the projection plane z(H^..<!5
for the irradiance map. The plane is defined so that the Up Vector is parallel to the ~{Mn{
vertical side of the plane. The irradiance incident on the selected surface is N&M~0iw
projected onto this plane. When the map is displayed, the up vector will point {6}eN|4~#
toward the top of the screen.