站长说的很对,补充一下: eG"iJ%I
Normal Vector YQ,IdWav
The Normal Vector is a vector in 3D space that is used to orient the projection W ;P1T"*A
plane for the irradiance map. The plane is defined to be perpendicular to the c72Oy+#
Normal Vector, and the irradiance incident on the selected surface is projected w_KGn17
onto this plane. When the map is displayed, the normal vector is pointing toward j72cSRv
you. "2HRuqf
Up Vector .x(&-
The Up Vector is a vector in 3D space that is used to orient the projection plane htX'bA
for the irradiance map. The plane is defined so that the Up Vector is parallel to the T5 5l-.>
vertical side of the plane. The irradiance incident on the selected surface is l
YH={jJ
projected onto this plane. When the map is displayed, the up vector will point fX[,yc;
toward the top of the screen.