站长说的很对,补充一下: _[F (8Qx"
Normal Vector I[nSf]Vm>
The Normal Vector is a vector in 3D space that is used to orient the projection ISa}Km>Q
plane for the irradiance map. The plane is defined to be perpendicular to the 6.5E
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Normal Vector, and the irradiance incident on the selected surface is projected u|(;SY
onto this plane. When the map is displayed, the normal vector is pointing toward iF,%^95=
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Up Vector %[S-"k
The Up Vector is a vector in 3D space that is used to orient the projection plane &FrUj>i
for the irradiance map. The plane is defined so that the Up Vector is parallel to the |Yb]@9>vn
vertical side of the plane. The irradiance incident on the selected surface is ,i RUR8
projected onto this plane. When the map is displayed, the up vector will point *{y({J
toward the top of the screen.