Parameters target Specifies the target texture.
Level 0 is the base image level. Level n is the nth mipmap reduction image. Description Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. The glTexSubImage2D subroutine redefines a contiguous subregion of an existing two-dimensional texture image. This region may not include any texels outside the range of the texture array as it was originally specified.