站长说的很对，补充一下： 8o,0='U
Normal Vector 0k\,z(e
The Normal Vector is a vector in 3D space that is used to orient the projection CL5^>. }
plane for the irradiance map. The plane is defined to be perpendicular to the Gb[J3:.
Normal Vector, and the irradiance incident on the selected surface is projected 5GJkvZtFY
onto this plane. When the map is displayed, the normal vector is pointing toward l >
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you. ckP AH E@
Up Vector ti1R6oSn
The Up Vector is a vector in 3D space that is used to orient the projection plane M9Sj@ ww
for the irradiance map. The plane is defined so that the Up Vector is parallel to the G2!<C -T{2
vertical side of the plane. The irradiance incident on the selected surface is pQ7elv]
projected onto this plane. When the map is displayed, the up vector will point N|)e {|k
toward the top of the screen.
