glCompressedTexImage2D

glCompressedTexImage2D: man3/glCompressedTexImage2D.xml

Texturing allows elements of an image array to be read by shaders. glCompressedTexImage2D loads a previously defined, and retrieved, compressed two-dimensional texture image if target is GL_TEXTURE_2D, or one of the cube map faces such as GL_TEXTURE_CUBE_MAP_POSITIVE_X. (see glTexImage2D ). If target is GL_TEXTURE_1D_ARRAY, data is treated as an array of compressed 1D textures. If target is GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_1D_ARRAY or GL_PROXY_TEXTURE_CUBE_MAP, no data is read from data, but all of the texture image state is recalculated, checked for consistency, and checked against the implementation's capabilities. If the implementation cannot handle a texture of the requested texture size, it sets all of the image state to 0, but does not generate an error (see glGetError ). To query for an entire mipmap array, use an image array level greater than or equal to 1. internalformat must be a known compressed image format (such as GL_RGTC ) or an extension-specified compressed-texture format. When a texture is loaded with glTexImage2D using a generic compressed texture format (e.g., GL_COMPRESSED_RGB ), the GL selects from one of its extensions supporting compressed textures. In order to load the compressed texture image using glCompressedTexImage2D, query the compressed texture image's size and format using 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.