站长说的很对,补充一下: [MuZ^'dR
Normal Vector ^=k=;
The Normal Vector is a vector in 3D space that is used to orient the projection /i~x.i3
plane for the irradiance map. The plane is defined to be perpendicular to the !FwNq'Q8$
Normal Vector, and the irradiance incident on the selected surface is projected D94bq_2}
onto this plane. When the map is displayed, the normal vector is pointing toward U&ytZ7iB
you. J&iSS9c
Up Vector pMJm@f
The Up Vector is a vector in 3D space that is used to orient the projection plane 6e8 gFQ"w2
for the irradiance map. The plane is defined so that the Up Vector is parallel to the :(\JY?+w
vertical side of the plane. The irradiance incident on the selected surface is O0FUJGuTS
projected onto this plane. When the map is displayed, the up vector will point ,+5:}hR+
toward the top of the screen.