glTexSubImage3D

glTexSubImage3D: man3/glTexSubImage3D.xml

Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is enabled. glTexSubImage3D redefines a contiguous subregion of an existing three-dimensional or two-dimensioanl array texture image. The texels referenced by data replace the portion of the existing texture array with x indices xoffset and xoffset + width - 1, inclusive, y indices yoffset and yoffset + height - 1, inclusive, and z indices zoffset and zoffset + depth - 1, inclusive. For three-dimensional textures, the z index refers to the third dimension. For two-dimensional array textures, the z index refers to the slice index. 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, height, or depth but such a specification has no effect. If a non-zero named buffer object is bound to the GL_PIXEL_UNPACK_BUFFER target (see glBindBuffer ) while a texture image is specified, data is treated as a byte offset into the buffer object's data store.

The glPixelStore modes affect texture images. glTexSubImage3D specifies a three-dimensional or two-dimenaional array subtexture for the current texture unit, specified with glActiveTexture.