glCompressedTextureSubImage1D

glCompressedTexSubImage1D: man4/glCompressedTexSubImage1D.xml

Texturing allows elements of an image array to be read by shaders. glCompressedTexSubImage1D and glCompressedTextureSubImage1D redefine a contiguous subregion of an existing one-dimensional texture image. The texels referenced by data replace the portion of the existing texture array with x indices xoffset and xoffset + width - 1, inclusive. 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 width of 0, but such a specification has no effect. internalformat must be a known compressed image format (such as GL_RGTC ) or an extension-specified compressed-texture format. The format of the compressed texture image is selected by the GL implementation that compressed it (see glTexImage1D ), and should be queried at the time the texture was compressed with glGetTexLevelParameter. 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.