站长说的很对,补充一下: FJDE48Vi
Normal Vector z)S6f79`Q
The Normal Vector is a vector in 3D space that is used to orient the projection PJcfiRa'jQ
plane for the irradiance map. The plane is defined to be perpendicular to the 8Z0x*Ssk
Normal Vector, and the irradiance incident on the selected surface is projected hbOXR.0z
onto this plane. When the map is displayed, the normal vector is pointing toward Bb:C^CHIQm
you. p]%di8&;N
Up Vector A*eVz]i,k&
The Up Vector is a vector in 3D space that is used to orient the projection plane VJ=>2'I
for the irradiance map. The plane is defined so that the Up Vector is parallel to the D3yTN"
vertical side of the plane. The irradiance incident on the selected surface is Jup)A`64
projected onto this plane. When the map is displayed, the up vector will point m/1FVC@*
toward the top of the screen.