站长说的很对,补充一下: ,v"YqD+GC5
Normal Vector T=ev[ mS
The Normal Vector is a vector in 3D space that is used to orient the projection H%D$(W
plane for the irradiance map. The plane is defined to be perpendicular to the eM8}X[
Normal Vector, and the irradiance incident on the selected surface is projected /Rl6g9}
onto this plane. When the map is displayed, the normal vector is pointing toward X&kp;W
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Up Vector K6R.@BMN
The Up Vector is a vector in 3D space that is used to orient the projection plane vN;mPd~g
for the irradiance map. The plane is defined so that the Up Vector is parallel to the =>-Rnc@
vertical side of the plane. The irradiance incident on the selected surface is =?!wXOg_
projected onto this plane. When the map is displayed, the up vector will point #\=F O>
toward the top of the screen.