站长说的很对,补充一下: -*1d!
Normal Vector ?gA 8x
The Normal Vector is a vector in 3D space that is used to orient the projection 8W*%aOi5+
plane for the irradiance map. The plane is defined to be perpendicular to the {'7B6
Normal Vector, and the irradiance incident on the selected surface is projected X_q\S g
onto this plane. When the map is displayed, the normal vector is pointing toward W!Gq.M
you. 6AAz
Up Vector V'z1
The Up Vector is a vector in 3D space that is used to orient the projection plane Vh|*p&
for the irradiance map. The plane is defined so that the Up Vector is parallel to the t%d Z-Ym
vertical side of the plane. The irradiance incident on the selected surface is cuax;0{%
projected onto this plane. When the map is displayed, the up vector will point @ a! #G
toward the top of the screen.