站长说的很对,补充一下: RUr ~u
Normal Vector ,L
The Normal Vector is a vector in 3D space that is used to orient the projection d>#',C#;
plane for the irradiance map. The plane is defined to be perpendicular to the Z[[*:9rY|
Normal Vector, and the irradiance incident on the selected surface is projected pGU.+[|(
onto this plane. When the map is displayed, the normal vector is pointing toward )j'Qi^;(D
you. .qe+"$K'n
Up Vector 8Mtd}{Fw*
The Up Vector is a vector in 3D space that is used to orient the projection plane %wl:>9]
for the irradiance map. The plane is defined so that the Up Vector is parallel to the #3ZAMV
vertical side of the plane. The irradiance incident on the selected surface is w)J-e gc
projected onto this plane. When the map is displayed, the up vector will point RCa1S^.
toward the top of the screen.