站长说的很对,补充一下: q<uLBaL_]r
Normal Vector vEp8Hc
The Normal Vector is a vector in 3D space that is used to orient the projection GWZXRUc
plane for the irradiance map. The plane is defined to be perpendicular to the ?N*@o.
Normal Vector, and the irradiance incident on the selected surface is projected g):jZU]b
onto this plane. When the map is displayed, the normal vector is pointing toward Xgc\O08
you. % P)}(e6y
Up Vector }UdqX1jz
The Up Vector is a vector in 3D space that is used to orient the projection plane {lUl+_58
for the irradiance map. The plane is defined so that the Up Vector is parallel to the {-`OE
vertical side of the plane. The irradiance incident on the selected surface is c] R![sa
projected onto this plane. When the map is displayed, the up vector will point uPv?Hq
toward the top of the screen.