站长说的很对,补充一下: M:PEY*4H
Normal Vector c:d.mkF\
The Normal Vector is a vector in 3D space that is used to orient the projection q6]T;)U&
plane for the irradiance map. The plane is defined to be perpendicular to the v@&UTU
Normal Vector, and the irradiance incident on the selected surface is projected QC,LHt?6
onto this plane. When the map is displayed, the normal vector is pointing toward hI$IBf>
you. 99KW("C1F
Up Vector *^+]`S
The Up Vector is a vector in 3D space that is used to orient the projection plane Pg''>6w>
for the irradiance map. The plane is defined so that the Up Vector is parallel to the [C0"vOTUb
vertical side of the plane. The irradiance incident on the selected surface is _spW~"|G
projected onto this plane. When the map is displayed, the up vector will point ` P,-NVB
toward the top of the screen.