站长说的很对,补充一下: >4:d)
Normal Vector k3~9;Z
The Normal Vector is a vector in 3D space that is used to orient the projection 0> f!S` *
plane for the irradiance map. The plane is defined to be perpendicular to the IGlR,tw_/
Normal Vector, and the irradiance incident on the selected surface is projected )!T~l(g
onto this plane. When the map is displayed, the normal vector is pointing toward O'y8q[2KE
you. +vBi7#&
Up Vector 5/meH[R\M
The Up Vector is a vector in 3D space that is used to orient the projection plane NYm"I`5w
for the irradiance map. The plane is defined so that the Up Vector is parallel to the $3-vW{<
vertical side of the plane. The irradiance incident on the selected surface is Ey6R/M)?:y
projected onto this plane. When the map is displayed, the up vector will point !X>u.}?g
toward the top of the screen.