站长说的很对,补充一下: QE+g
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Normal Vector &J]K3w1p
The Normal Vector is a vector in 3D space that is used to orient the projection =j_4S<
plane for the irradiance map. The plane is defined to be perpendicular to the )u&|_&g{}J
Normal Vector, and the irradiance incident on the selected surface is projected z|J_b"u4
onto this plane. When the map is displayed, the normal vector is pointing toward *8 A
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Up Vector "S]0
The Up Vector is a vector in 3D space that is used to orient the projection plane `g?Negt\v
for the irradiance map. The plane is defined so that the Up Vector is parallel to the M]
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vertical side of the plane. The irradiance incident on the selected surface is [85spub&}
projected onto this plane. When the map is displayed, the up vector will point (S5R!lpO
toward the top of the screen.