站长说的很对,补充一下: >o[T#U
Normal Vector V&f3>#n\
The Normal Vector is a vector in 3D space that is used to orient the projection ~o8$/%Oeb/
plane for the irradiance map. The plane is defined to be perpendicular to the
M,6AD]
Normal Vector, and the irradiance incident on the selected surface is projected [}VEDx
onto this plane. When the map is displayed, the normal vector is pointing toward Oi{jzP
you. )qxL@w.
Up Vector N,;Bl&EU
The Up Vector is a vector in 3D space that is used to orient the projection plane 7sFjO/a*
for the irradiance map. The plane is defined so that the Up Vector is parallel to the E]e6a^J#
vertical side of the plane. The irradiance incident on the selected surface is V 1Fdt+#
projected onto this plane. When the map is displayed, the up vector will point 7zNyH(.
toward the top of the screen.