站长说的很对,补充一下: u8[jD^
Normal Vector OH~I+=}.
The Normal Vector is a vector in 3D space that is used to orient the projection >@^j9{\
plane for the irradiance map. The plane is defined to be perpendicular to the ~Q1%DV.
Normal Vector, and the irradiance incident on the selected surface is projected [0n&?<<
onto this plane. When the map is displayed, the normal vector is pointing toward 6z+*H7Qz
you. lb #`f,r>
Up Vector 5LxzET"P
The Up Vector is a vector in 3D space that is used to orient the projection plane :*lB86Ly
for the irradiance map. The plane is defined so that the Up Vector is parallel to the $qhVow5~
vertical side of the plane. The irradiance incident on the selected surface is qd?k#Gw&
projected onto this plane. When the map is displayed, the up vector will point mg4:N
toward the top of the screen.