Subroutine Purpose Specifies a two-dimensional texture subimage.
Parameters target Specifies the target texture.
Level 0 is the base image level. Level n is the n th mipmap reduction image. Description Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. This region may not include any texels outside the range of the texture array as it was originally specified. It is not an error to specify a subtexture with zero width or height, but such a specification has no effect.